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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-K

For the fiscal year ended December 31, 2015

OR

Commission File Number 001-36853

ZILLOW GROUP, INC.

(Exact name of registrant as specified in its charter)

(206) 470-7000

@ZillowGroup

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark whether the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act:    Yes  x    No  ¨

Indicate by check mark whether the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act:    Yes  ¨    No  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act):    Yes  ¨    No  x

As of June 30, 2015, the last business day of the Registrant’s most recently completed second fiscal quarter, the aggregate market value of the Registrant’s Class A common stock held by non-affiliates based upon the closing price of such shares on The Nasdaq Global Select Market on such date was $4,380,916,635. No shares of the Registrant’s Class C capital stock were outstanding as of June 30, 2015.

As of February 4, 2016, 53,320,939 shares of the Registrant’s Class A common stock, 6,217,447 shares of Class B common stock and 118,992,759 shares of Class C capital stock were outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

The information required by Part III of this Report, to the extent not set forth herein, is incorporated in this Report by reference to the Registrant’s definitive proxy statement relating to the 2016 annual meeting of shareholders. The definitive proxy statement will be filed with the Securities and Exchange Commission within 120 days after the end of the 2015 fiscal year.

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ZILLOW GROUP, INC.

Annual Report on Form 10-K

for the Fiscal Year Ended December 31, 2015

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As used in this Annual Report on Form 10-K, the terms “Zillow Group,” “the Company,” “we,” “us” and “our” refer to Zillow Group, Inc., unless the context indicates otherwise.

NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K, including the sections entitled “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” “Risk Factors” and “Business,” contains forward-looking statements based on our management’s beliefs and assumptions and on information currently available to our management. Forward-looking statements include all statements that are not historical facts and generally may be identified by terms such as “believe,” “may,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “could,” “would,” “project,” “plan,” “expect” or the negative or plural of these words or similar expressions.

These forward-looking statements are subject to a number of risks, uncertainties and assumptions, including those risks, uncertainties and assumptions described in Part I, Item 1A (Risk Factors) of this report. Moreover, we operate in a very competitive and rapidly changing environment. New risks emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the effect of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties and assumptions, the forward-looking events and circumstances discussed in this report may not occur and actual results could differ materially and adversely from those anticipated or implied in the forward-looking statements.

You should not rely on forward-looking statements as predictions of future events. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee that the future results, levels of activity, performance or events and circumstances reflected in the forward-looking statements will be achieved or occur. Moreover, except as required by law, neither we nor any other person assumes responsibility for the accuracy and completeness of the forward-looking statements, and we undertake no obligation to update publicly any forward-looking statements for any reason after the date of this report to conform these statements to actual results or to changes in our expectations.

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PART I

Item 1. Business

Mission

Our mission is to build the world’s largest, most trusted and vibrant real estate marketplace.

Overview

Zillow Group, Inc. operates the leading real estate and home-related information marketplaces on mobile and the Web, with a complementary portfolio of brands and products to help people find vital information about homes and connect with local professionals. Zillow Group’s brands focus on all stages of the home lifecycle: renting, buying, selling, financing and home improvement. The Zillow Group portfolio of consumer brands includes real estate and rental marketplaces Zillow, Trulia, StreetEasy and HotPads. In addition, Zillow Group provides advertising services to tens of thousands of real estate agents and rental and mortgage professionals, helping maximize business opportunities and connect to millions of consumers. We also own and operate a number of brands that offer technology solutions to real estate, rental and mortgage professionals, including DotLoop, Mortech, Diverse Solutions and Retsly. Zillow was incorporated as a Washington corporation in December 2004, and we launched the initial version of our website, Zillow.com, in February 2006. Zillow Group was incorporated as a Washington corporation in July 2014 in connection with our acquisition of Trulia. Upon the closing of the Trulia acquisition in February 2015, each of Zillow and Trulia became wholly owned subsidiaries of Zillow Group.

Our living database of more than 110 million U.S. homes—homes for sale, homes for rent and homes not currently on the market—attracts an active and vibrant community of users. Individuals and businesses that use Zillow Group’s mobile applications and websites have updated information on more than 60 million homes and added more than 370 million home photos, creating exclusive home profiles not available anywhere else. These profiles include detailed information about homes, including property facts, listing information and purchase and sale data. We provide this information to our users where, when and how they want it, through our industry-leading mobile applications that enable consumers to access our information when they are curbside, viewing homes, and through our websites. Using complex, proprietary automated valuation models, we provide current home value estimates, or Zestimates, and current rental price estimates, or Rent Zestimates, on more than 100 million U.S. homes.

Consumers increasingly are turning to the Internet and mobile devices for real estate information. For the three months ended December 31, 2015, 123.7 million average monthly unique users visited Zillow Group’s mobile applications and websites, representing year-over-year growth of 61%. For additional information regarding key growth drivers, see “Key Growth Drivers” in the “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” More than 65% of Zillow’s traffic now comes from a mobile device; on weekends it’s more than 70%. We operate the most popular suite of mobile real estate applications across all major mobile platforms. For example, on our flagship Zillow brand, during December 2015, more than 440 million homes were viewed on Zillow on a mobile device, or 165 homes per second. We monetize our marketplace business on mobile in the same way we do on our web platform.

Real estate, rental, mortgage and home improvement professionals are a critical part of home-related marketplaces. We have created a trusted and transparent marketplace where consumers can search and read reviews on local real estate, rental, mortgage and home improvement professionals and contact those professionals on their own terms.

Our home-related marketplaces benefit from network effects. As more consumers come to our mobile applications and websites to use our products and services, more real estate, rental, mortgage and home improvement professionals contribute content to distinguish themselves, thereby making our marketplaces more useful and attracting additional consumers.

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Our revenue has grown significantly since our initial website launch in 2006. For the year ended December 31, 2015, we generated revenue of $644.7 million, as compared to $325.9 million for the year ended December 31, 2014, an increase of 98%. We generate revenue from the sale of advertising services and our suite of tools to businesses and professionals primarily associated with the real estate, rental and mortgage industries. These professionals include local real estate and rental professionals, mortgage professionals and brand advertisers. Our two revenue categories are marketplace revenue and display revenue.

Marketplace revenue for the year ended December 31, 2015 consisted of real estate, mortgages, and Market Leader revenue. Real estate revenue primarily includes revenue from the sale of advertising services and a suite of tools to real estate professionals, as well as revenue generated by Zillow Group Rentals, which includes our rentals marketplace and suite of tools for rental professionals. Mortgages revenue primarily includes advertising sold to mortgage lenders and other mortgage professionals, as well as revenue generated by Mortech, which provides subscription-based mortgage software solutions, including a product and pricing engine and lead management platform. Market Leader revenue primarily includes revenue from the sale of a comprehensive premium software-as-a-service based marketing product typically sold to real estate professionals as a bundle of products under a fixed fee subscription. Market Leader revenue is included in our results of operations from February 17, 2015 through the date of divestiture of September 30, 2015.

Display revenue primarily consists of graphical mobile and web advertising sold on a cost per thousand impressions (“CPM”) or cost-per-click (“CPC”) basis to advertisers promoting their brands on our mobile applications and websites and our partner websites. Impressions are delivered when a sold advertisement appears on pages viewed by users of our mobile applications and websites.

Acquisition of Trulia, Inc.

Effective February 17, 2015, pursuant to the Agreement and Plan of Merger dated as of July 28, 2014 (the “Merger Agreement”) by and among Zillow, Inc. (“Zillow”), Zillow Group, and Trulia, Inc. (“Trulia”), Zillow Group acquired Trulia, and Zillow and Trulia became wholly owned subsidiaries of Zillow Group. Upon completion of the acquisition, each outstanding share of Class A common stock of Zillow was converted into the right to receive one share of fully paid and nonassessable Class A common stock of Zillow Group, each outstanding share of Class B common stock of Zillow was converted into the right to receive one share of fully paid and nonassessable Class B common stock of Zillow Group, and each outstanding share of Trulia common stock was converted into the right to receive 0.444 of a share of fully paid and nonassessable Class A Common Stock of Zillow Group.

The total purchase price of Trulia was approximately $2.0 billion. We have included Trulia’s results of operations prospectively after February 17, 2015, the date of acquisition. For additional information regarding the transaction with Trulia, see Note 7 to our consolidated financial statements.

On February 17, 2015, in connection with the acquisition, Zillow Group undertook a restructuring plan that resulted in a total workforce reduction of nearly 350 employees, primarily to eliminate overlapping positions in the sales and marketing functions related to Trulia’s workforce at its Bellevue, Denver, New York and San Francisco locations. The restructuring plan is a result of the integration of Trulia’s business and operations with and into Zillow Group’s business. Employees directly affected by the restructuring plan were provided with severance payments, stock vesting acceleration and outplacement assistance. For additional information regarding the restructuring, see Note 18 to our consolidated financial statements.

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Industry Dynamics

The Importance of Homes

Homes are the center of peoples’ lives, the focus of some of their most important decisions and often their most valuable assets. In addition to whether to buy, sell or rent, consumers make many other important home-related decisions throughout their lifetimes, including decisions relating to refinancing or home equity loans, home maintenance and home improvement. Residential real estate is one of the largest sectors of the U.S. economy and supports millions of professionals that provide services related to home purchases and sales, rentals, home financings, and home maintenance and improvement.

Large Market Opportunities

Based on external and internal assessments, we believe our current addressable markets include the following:

Purchase and Sale—Sales of approximately 5.3 million existing and 490 thousand new homes in the United States in 2015 had an aggregate transaction value of approximately $1.6 trillion, according to data published in 2015 by the U.S. Census Bureau and in 2016 by the National Association of REALTORS^®. There are approximately 1.9 million licensed real estate professionals in the United States, according to data published in 2012, 2013 and 2014 by the Association of Real Estate License Law Officials. In an effort to acquire new client relationships and sell homes, U.S. real estate agents and brokers spent an estimated $8.9 billion on residential advertising in 2015, according to a forecast from Borrell Associates released in 2016. In addition, U.S. real estate developers spent an estimated $1.7 billion on residential advertising in 2015, also according to a forecast from Borrell Associates released in 2016. In the United States, there are 205 million people residing in owner-occupied housing, according to data published by the U.S. Census Bureau in November 2015. Approximately 29% of movers in 2015, or 10.5 million people, were homeowners, according to the U.S. Census Bureau migration data published in November 2015.

Rentals—In the third quarter of 2015, there were approximately 46.0 million rental housing units in the United States, with a national vacancy rate of 7.3%, according to data published by the U.S. Census Bureau in October 2015. According to data published by the U.S. Census Bureau from the American Housing Survey and the Current Population Survey/Housing Vacancy Survey, approximately:

According to a forecast from Borrell Associates released in 2016, U.S. rental property managers spent an estimated $3.5 billion on advertising in 2015, which excludes lease concessions. In the United States, there are 107.6 million people residing in rental housing units, according to data published by the U.S. Census Bureau in 2015. Approximately 71% of movers in 2015, or 25.9 million people, were renters, according to the U.S. Census Bureau migration data published in November 2015.

Home Financing—According to a forecast from the Mortgage Bankers Association published in January 2016, approximately $1.5 trillion in U.S. residential mortgage originations occurred in 2015. U.S. residential mortgage providers spent approximately $4.4 billion in 2015 marketing their services and loan products to mortgage borrowers, according to a forecast from Borrell Associates released in 2016.

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Home Maintenance and Improvement—Spending on home improvements and repairs totaled $298 billion in 2013, according to the Joint Center for Housing Studies of Harvard University in a January 2015 report. As noted in the report, 82% of home improvement and repair spending was on owner-occupied homes, with the remainder on rental units. Spending on advertising by the home improvement industry was approximately $10.9 billion in 2014, according to data presented in industry research reports from IBISWorld Inc. released in 2014.

Highly Fragmented, Local and Complex Market

The market for residential real estate transactions and home-related services is highly fragmented, local and complex. Each home has unique characteristics, including location, value, size, style, age and condition. Each consumer approaches home-related transactions with a personal set of objectives, priorities and values. Real estate agents generally operate in local markets as independent contractors with different experiences and skills. These conditions create challenges for consumers and real estate, rental, mortgage and home improvement professionals alike. Consumers are challenged to find information about homes and to find real estate, rental, mortgage and home improvement professionals who fit their individual needs. Real estate, rental, mortgage and home improvement professionals are challenged to efficiently advertise their services and identify new clients, and to measure the effectiveness of their marketing efforts.

Absence of Consumer Orientation

Historically, consumers had minimal access to comprehensive and objective residential real estate data, even though many home-related decisions are extraordinarily information-intensive. While real estate, rental, mortgage and home improvement professionals had some data, consumers did not have free, independent and easy access to data. Even when accessible, the data were difficult to interpret and analyze.

Increasing Role of Mobile Technologies and the Internet

Consumers are increasingly turning to mobile devices and the Internet to access real estate information. With the widespread adoption of mobile and location-based technologies, consumers increasingly expect home-related information to be available on their mobile devices where, when and how they want it. More than 65% of Zillow’s traffic now comes from a mobile device; on weekends it’s more than 70%. We believe that the technological platform shift from desktop computers to mobile devices benefits technology leaders like Zillow Group that are quick to innovate.

Competitive Advantages

We believe we have the following competitive advantages:

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We synthesize data from hundreds of automated feeds, representing information from tens of thousands of public and private sources. Applying extensive computer analytics to the data, we transform it into information that is accessible, understandable and useful.

We refer to the database as “living” because the information is continually updated by the combination of our proprietary algorithms, synthesis of third-party data from hundreds of sources, and through improvements by us and, importantly, by our community of users. User-generated content from owners, agents and others enriches our database with photos and additional property information. Individuals and businesses that use Zillow’s mobile applications and websites have updated information on more than 60 million homes in our database and added more than 370 million home photos, creating exclusive home profiles not available anywhere else. Our inimitable database enables us to create content, products and services not available anywhere else, and attracts an active, vibrant community of users. As of December 31, 2015, we had published more than 1.8 million reviews, including more than 1.5 million reviews of local real estate agents and more than 210,000 reviews of mortgage professionals submitted by our users on Zillow. In addition, our users had submitted more than one million questions and answers in our discussion forum, Zillow Advice. Zillow Advice and Trulia Voices allow consumers to ask questions of real estate, rental, mortgage and home improvement professionals and other consumers and quickly learn more about homes and real estate topics of interest. In particular, many of our dedicated active contributors devote substantial time sharing their expertise about Zillow and the real estate market on Zillow Advice and Trulia Voices. Real estate, rental, mortgage and home improvement professionals who participate in Zillow Advice and Trulia Voices play a key role in helping to educate consumers, and benefit from exposure to consumers and resulting referrals.

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Growth Strategies

Our growth strategies are:

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Advertising Products and Services

We provide advertising products and services for real estate, rental, mortgage and home improvement professionals that enable them to create and promote useful content for consumers.

Marketplace Advertising

Premier Agent Program

Zillow Group’s Premier Agent program offers a suite of marketing and business technology solutions to help real estate agents grow their businesses and personal brands. The Premier Agent program allows agents to select products and services that they can tailor to meet their business and advertising needs. The program has three tiers of participation including Premier Platinum, our flagship product, as well as Premier Gold and Premier Silver, to meet different marketing and business needs of a broad range of agents. All tiers of Premier Agents receive access to a dashboard portal on our website that provides individualized program performance analytics, as well as our personalized website service, and our free customer relationship management, or CRM, tool that captures detailed information about each contact made with a Premier Agent through our mobile and web platforms. Our Premier Gold product also includes featured listings whereby the agent’s listings will appear at the top of search results on our mobile and web platforms. Our Premier Platinum product includes the dashboard portal on our website, our personalized website service, our CRM tool, featured listings, and inclusion on our buyer’s agent list, whereby the agent appears as

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the agent to contact for listings in the purchased zip code. Our multi-tiered Premier Agent advertising program, along with our DotLoop collaboration platform, Diverse Solutions agent website services, our CRM tools, and our rentals syndication tool, extend our platform beyond just marketing services for real estate agents to a platform that also includes other types of trade services and tools.

Trulia Real Estate Products

Our Trulia real estate products are primarily sold on a fixed fee subscription basis, and include Trulia Local Ads, Trulia Mobile Ads, Trulia Pro with featured listings and Trulia Seller Ads. Prior to the August 2015 integration of certain of Zillow’s and Trulia’s advertising products, Trulia Local Ads and Trulia Mobile Ads enabled real estate professionals to promote themselves on Trulia’s search results pages and property details pages for a local market area. Real estate professionals purchased subscriptions to these products based upon their specified market share for a city or zip code, at a fixed monthly price, for periods ranging from one month to one year, with pricing depending on demand, location, and the percentage of market share purchased. Following the August 2015 agent advertising product integration, Trulia Local Ads and Trulia Mobile Ads products are no longer sold by Zillow Group. Trulia’s featured listings product allows real estate professionals to receive prominent placement of their listings in Trulia’s search results. Real estate professionals sign up for new subscriptions to this product at a fixed monthly price for periods that generally range from six months to 12 months. Trulia Seller Ads enable real estate professionals to generate leads from consumers interested in selling their homes.

Mortgages

In our mortgages marketplace, consumers request free, personalized quotes in response to their submission of limited anonymous data, such as specific loan amount, zip code, purchase price or estimated home value, and credit score. For the year ended December 31, 2015, there were approximately 46.8 million mortgage loan information requests submitted by consumers. Consumers decide if and when to contact the mortgage professionals who provide quotes. User-generated ratings and reviews of mortgage professionals are provided as a powerful tool to help consumers shop for their loans. Our custom mortgage quote service is operated by our wholly owned subsidiary, Zillow Group Mortgages, Inc., a licensed mortgage broker, pursuant to a support services agreement.

Zillow Group Rentals

Zillow Group continues to develop its rental marketplace on mobile and Web. Zillow Group Rentals is a marketplace for consumers and suite of tools for rental professionals, and is the largest rental network on the Web. Zillow Group Rentals includes listing distribution across Zillow, Trulia and HotPads, reaching millions of rental shoppers each month. Zillow Rent Connect advertisers gain access to the leading technology platform that connects rental properties with consumer contacts.

Display Advertising

Our display advertising primarily consists of graphical mobile and web advertising sold on a CPM basis. We offer customers display advertising opportunities on our mobile applications through display ads that are optimized for the mobile experience, on our home page, and on individual web pages, through graphical displays and text links.

Information Products and Services

We provide consumers with information products and services to enable them to make intelligent decisions about homes.

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Zestimates and Rent Zestimates

Our Zestimate and Rent Zestimate valuations are computed using complex, proprietary algorithms we have developed and refined through years of statistical analysis and technological development.

A Zestimate is our estimated current market value of a home. We generate Zestimates using a variety of information, including:

We use proprietary automated valuation models that apply advanced algorithms to analyze our data to identify relationships within a specific geographic area between home-related data and actual sales prices. Home characteristics, such as square footage, location or the number of bathrooms, are given different weights according to their influence on home sale prices in each specific geographic area over a specific period of time, resulting in a set of valuation rules, or models, that are applied to generate each home’s Zestimate.

To improve the accuracy of our Zestimates, our algorithms automatically remove or reconcile data that would otherwise inappropriately skew the valuation rules. In addition, our algorithms will automatically generate a new set of valuation rules based on the constantly changing universe of data included in our database. This allows us to provide timely home value information on a massive scale, updated three times a week.

We publicly disclose the accuracy of our Zestimates to further empower consumers in assessing a home’s value. The accuracy may be impacted by a variety of factors, including the amount of data about homes we have for a particular geographic area.

A Rent Zestimate is our estimated current monthly rental price of a home, computed using similar automated valuation models we have designed to address the unique attributes of a rental home. We estimate rental prices on more than 100 million homes, including apartments, single-family homes, condominiums and townhomes.

Zillow Digs

Zillow Digs is the hub for home improvement and design on Zillow. Consumers can browse millions of design ideas for every room, budget and style. Product and paint tags identify the elements in the space, giving consumers the information to recreate the look of the room in their own space. Each product tag provides retailer information, pricing and the link to purchase the item. Additionally, Zillow Digs Estimates give consumers the estimated cost of thousands of real bathrooms and kitchens in Zillow Digs’ ever-increasing portfolio of photos and are computed using Zillow’s proprietary algorithm, which includes real-world data from local contractors such as size, materials, finish level, and regional labor and material rates.

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Rich, Searchable Home-Related Data and Analysis

We provide consumers and real estate professionals with a rich set of home-related information. Through our mobile applications and websites, users can access detailed information about homes, including:

Consumers and real estate professionals can update property information by, for example, adding home photos and personalized information regarding the neighborhood or school district, creating exclusive home profiles not available anywhere else.

Our map-based user interface enables our users to search, navigate and zoom to areas of interest and find and compare home information quickly and efficiently from a variety of different perspectives across homes, neighborhoods, cities, counties and other geographical regions. Our consumer search experience supports complex search queries and filters across our data set of homes, allowing consumers to customize their searches and gain actionable insights.

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Our team of economists and statisticians generates unbiased local and national real estate data and analysis on 908 metropolitan areas and approximately 11,200 individual neighborhoods that we provide to consumers and real estate, rental, mortgage and home improvement professionals at no cost. This gives our users access to local market trends and data, such as home price cuts, list to sale price ratio and foreclosure data that was historically not easily obtained, if available at all. Users can compare these metrics across neighborhoods and different time periods using our real-time charting and filtering.

For Sale and Rental Listings

We provide comprehensive for sale and rental listings through relationships with real estate brokerages, real estate listings aggregators, multiple listing services, apartment management companies, home builders and other third parties. In addition, we provide consumers with access to exclusive home listings, such as our Make Me Move listings, which are a homeowner’s posted price at which they would be willing to move. We also show listings that may not be available on other sources, including for sale by owner, pre-market inventory, including our Coming Soon listings, and rental listings. Real estate agents and landlords may feature and gain more exposure for their listings through our advertising products.

Historically, a substantial portion of the listings displayed on our mobile applications and websites was provided to us by a single real estate listing aggregator pursuant to platform services agreements. These listings provided revenue-generating opportunities as impressions were delivered through our mobile applications and websites. Pursuant to agreements with the real estate listing aggregator, the platform services agreements expired on April 7, 2015. Through various data acquisition efforts, including the January 2015 launch of the Zillow Data Dashboard, a new listing management and reporting platform that allows Multiple Listing Services, or MLSs, and brokers to provide listings directly to Zillow Group, we have made significant progress in replacing the listings previously provided under the platform services agreements. Since January 2015, nearly 400 MLSs have signed agreements to send listings directly to Zillow and Trulia.

Marketplace of Real Estate Agents

We present consumers with ratings and contact information for the listing agent and local buyer’s agents alongside home profiles and listings for homes to assist them in evaluating and selecting the real estate agent best suited for them. We enhance this offering by providing an online professional directory for consumers to search and contact real estate professionals that they might wish to engage. Our directory includes rich profiles of real estate professionals, including more than 1.8 million ratings and reviews provided by our users, allowing consumers to evaluate these agents based on a number of criteria, including neighborhood specialization, number of listings and number of contributions to Zillow Advice and Trulia Voices.

Marketplace of Mortgage Professionals

In our mortgages marketplace, consumers can anonymously request free, personalized mortgage quotes from consumer-rated and -reviewed mortgage professionals. Consumers can then choose to contact those mortgage professionals at their discretion. For the year ended December 31, 2015, there were approximately 46.8 million mortgage loan information requests submitted by consumers. As of December 31, 2015, we had published more than 210,000 reviews of mortgage professionals submitted by our users.

Home-Related Advice and Discussions

Consumers have many questions and often seek advice during various stages of their home-ownership lifecycle. The Zillow Advice section of our Zillow.com website and Trulia Voices section of our Trulia.com website capture questions and discussion topics from our users, both consumers and real estate, rental, mortgage and home improvement professionals. This allows our consumers to ask questions of other consumers and real estate, rental, mortgage and home improvement professionals and quickly learn more about relevant topics. Our

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users have submitted more than one million questions and answers to Zillow Advice as of December 31, 2015. Zillow Advice and Trulia Voices also provide real estate, rental, mortgage and home improvement professionals with an opportunity to help educate consumers and demonstrate their local expertise. These discussions and content are also indexed and searchable by geography and other custom parameters, allowing users to quickly find the information they seek. Email updates are used to provide ongoing monitoring and delivery of posts related to topics of interest.

Mobile Access

We operate the most popular suite of mobile real estate applications across all major mobile platforms. Our mobile real estate applications provide consumers and real estate, rental, mortgage and home improvement professionals with location-based access to many of our products and services, including Zestimates, Rent Zestimates, for sale and rental listings and extensive home-related data. Through our mobile applications, for example, a consumer standing curbside at a home for sale can learn about the home’s for-sale price, Zestimate, number of bedrooms, square footage and past sales, as well as similar information about surrounding homes. The consumer can call a real estate professional through our mobile applications to get more information or schedule a showing. For example, on our flagship Zillow brand, during December 2015, more than 440 million homes were viewed on Zillow on a mobile device, which equates to 165 homes per second.

Marketing

We believe Zillow Group has considerable opportunity to increase brand awareness and grow traffic through product development, targeted advertising programs and strategic partnerships. As such, we selectively advertise to consumers and professionals in various online and offline channels that have tested well for us and pursue strategic partnerships that drive traffic and brand awareness for Zillow Group.

At Zillow Group, marketing begins with product development, which then becomes amplified by effective brand advertising and marketing communications. We create immersive consumer products that people want to use frequently, talk about and share. The engaging nature of our products enables us to execute compelling advertising campaigns integrated with our robust and viral communications program, which together comprise the primary drivers of our brand awareness and traffic acquisition efforts. For example, for our flagship Zillow brand, we launched our consumer brand with communications at the core of our marketing strategy. Next, after years of vigorous field testing, we began large-scale national advertising in early 2013 on television and across other complementary channels, which has continued through the year ended December 31, 2015. In part as a result of these advertising efforts, our traffic has grown to 123.7 million average monthly unique users for the three months ended December 31, 2015, an increase of 61% compared to the three months ended December 31, 2014. The majority of our traffic and brand awareness comes direct, not dependent on search engines, with demonstrated consumer intent to visit the Zillow Group brands.

The communications team for our flagship Zillow brand includes former print and broadcast journalists who have established Zillow Group as an authoritative source for information on a broad range of home and real estate-related subjects. A typical week includes commentary from our real estate experts across dozens of national print and broadcast media outlets, guest opinion pieces or blog posts by our chief economist, and wide-ranging national and local media coverage of Zillow Group products, listings, data and consumer tips. We also produce considerable home and real estate-related content on Zillow Blog and Trulia’s Blog that is syndicated across dozens of prominent media sites. Zillow Blog and Trulia’s Blog content ranges from real estate market trends, to home financing tips, to celebrity real estate listings.

We focus substantial public relations effort around the marketing of our Zillow Real Estate Market Reports, which are in-depth reports produced by our economics and analytics bureau for 794 U.S. markets. Data is released on a monthly and quarterly basis, and the data is widely used by government entities such as the Federal Reserve and Congressional Oversight Panel, as well as regularly featured in respected media outlets such as the

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Wall Street Journal, New York Times, Bloomberg, Reuters and across numerous national network and cable news shows including CNBC, CNN, Fox News and Bloomberg. We believe the considerable effort we have spent on public relations and social media has allowed us to build large and credible brands.

Our living database of homes creates significant opportunities for home-ownership lifecycle marketing. A typical person will at various times in life be a renter, buyer, homeowner, remodeler, mortgage refinancer or seller, and this presents opportunities to communicate with consumers over many years before, during and after a transaction. We actively communicate with our users through email and social media channels.

Sales, Consumer Care and Customer Support

Our sales teams are responsible for generating advertising customers across our mobile applications and websites.

Our largest sales teams sell our Premier Agent products to real estate agents, and are located in Seattle, Washington, Denver, Colorado, and Irvine, California. We also have a sales team in Seattle, Washington that sells our rental products to rental professionals. In addition, we have sales teams in Seattle, Washington, New York, New York and Lincoln, Nebraska that support sales in our mortgage marketplaces and display advertising. We attract customers through a combination of outbound calling and inbound customer requests generated from our websites and event marketing activities. We also maintain a field sales team in San Francisco, California, New York, New York, Chicago, Illinois, and Detroit, Michigan, to specifically target larger advertising customers in the real estate and related content categories, such as real estate brokerages, home builders, lenders and home service providers, as well as advertisers in the telecommunications, automotive, insurance and other industries.

We believe that consumer care and customer support are important to our success. Our consumer care and customer support teams are located in Seattle, Washington, and Denver, Colorado. Our customer support team responds to commercial and technical issues from our advertisers, and our consumer care team responds to consumer issues from our user community. The Zillow Advice and Trulia Voices forums augment our consumer care by enabling consumers to obtain answers to questions from our employees and other members of our user community, including real estate, rental, mortgage and home improvement professionals.

Technology and Infrastructure

Zillow Group is a data- and technology-driven company. Our technical infrastructure, mobile applications and websites are built to provide consumers and real estate, rental, mortgage and home improvement professionals with access to rich real estate data and powerful online tools to help them accomplish their home-related goals. Many of our services are available through real-time web-based application programming interfaces that allow our information to be easily integrated into third-party websites. We provide HTML and JavaScript-based widgets to allow easy integration of Zillow Group information onto other websites, with little custom programming. Our technology platform is built using industry-leading third-party and internally developed software as well as open source technologies. This combination allows for rapid development and release of high-performance software in a cost-effective and scalable manner. Our mobile applications and websites are designed to have high availability, from the Internet connectivity providers we choose, to the servers, databases and networking hardware that we deploy. We design our systems so that the failure of any individual component is not expected to affect the overall availability of our platform. We also leverage content delivery networks and use other third-party cloud computing services, including map-related and ad serving services, to ensure fast and local access to content. We employ a host of encryption, antivirus, firewall, monitoring, and patch-management technology to protect and maintain our systems.

Our Zillow technical infrastructure, mobile applications and websites are hosted at a third-party facility located in the Seattle area. Additionally, we utilize third-party web services for cloud computing and storage to assist in service growth and redundancy. Content delivery network solutions have been put in place to ensure fast and local access to content. Development and test environments are located either in a data center we manage at our corporate headquarters or are hosted by third-party cloud computing infrastructure.

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We currently manage our Trulia mobile applications and website from three locations. The primary location where we host our production environment is within a shared data center in Santa Clara, California. We also have a second hosted facility located in Denver, Colorado where we support our production environment and provide redundancy, backup and load balancing. We use a third hosted facility located in Oakland, California for production service backup and for our development environment.

For information about our research and development costs, see Note 2 of the accompanying notes to our consolidated financial statements included within this annual report.

Intellectual Property

We protect our intellectual property through a combination of trademarks, trade dress, domain names, copyrights, trade secrets and patents, as well as contractual provisions and restrictions on access to our proprietary technology.

Our trademarks registered in the United States and several other jurisdictions include, but are not limited to, “Zillow,” “Trulia,” “Zestimate,” “Premier Agent,” “Dueling Digs,” “Make Me Move,” “Diverse Solutions,” “dsIDXpress,” “Mortech,” “Marksman,” “Hotpads,” “StreetEasy,” “Retsly,” “dotloop,” “Digs,” “Find Your Way Home,” the Z in a house logo, the Trulia marker logo, as well as logos that correspond with several of our other trademarks. We also have filed other trademark applications in the United States and certain other jurisdictions and will pursue additional trademark registrations to the extent we believe it will be beneficial and cost-effective.

We have 18 patents issued in the United States and internationally. These patents cover proprietary techniques that relate to determining a current value for a real estate property, performing summarization of geographic data points in response to zoom selection, the incorporation of individual aerial images and incorporating visual information into a master planar image, the collection, storage and display of home attribute values, providing for a multi-faceted search, and other proprietary techniques relevant to our products and services. We have 47 patent applications pending in the United States and internationally, which seek to cover proprietary techniques relevant to our products and services. We intend to pursue additional patent protection to the extent we believe it will be beneficial and cost-effective.

We are the registered holder of a variety of domestic and international domain names that include “Zillowgroup.com,” “Zillow.com,” “Trulia.com,” “RealEstate.com,” “DiverseSolutions.com,” “Mortech.com,” “HotPads.com,” “Streeteasy.com,” “DotLoop.com,” “Retsly.com,” and other similar variations.

In addition to the protection provided by our intellectual property rights, we enter into confidentiality and proprietary rights agreements with our employees, consultants, contractors and business partners. Our employees and contractors are also subject to invention assignment provisions. We further control the use of our proprietary technology and intellectual property through provisions in both our general and product-specific terms of use on our mobile applications and websites.

Competition

We face competition to attract consumers to our mobile applications and websites and to attract advertisers to purchase our advertising products and services.

Competition for Consumers

We compete for the attention of consumers with companies that operate, or could develop, national and local real estate, rental, mortgage and home improvement mobile applications and websites. We compete for consumers primarily on the basis of the quality of the consumer experience, the utility of the data and services we provide, the breadth, depth and accuracy of information, and brand awareness and reputation. We believe we compete favorably on these factors.

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Competition for Advertisers

We compete for advertising customers, such as real estate professionals, with media companies, including companies dedicated to providing mobile and web-based real estate, rental, mortgage and home improvement information and services to real estate professionals and consumers, local brokerage sites and major Internet portals, general search engines and social media sites, as well as other online companies. We also compete for a share of advertisers’ overall marketing budgets with traditional media such as newspapers, television, magazines, and home/apartment guide publications, particularly with respect to advertising dollars spent at the local level by real estate agents, mortgage professionals, property managers or rental agents to advertise their qualifications or listings. We compete for advertising revenue based on perceived return on investment and perceived transaction readiness and overall quality of consumer leads, the effectiveness and relevance of our advertising products, pricing structure and our ability to effectively deliver types of ads to targeted demographics. We believe we compete favorably on these factors.

Government Regulation

We are affected by laws and regulations that apply to businesses in general, as well as to businesses operating on the Internet and through mobile applications. This includes a continually expanding and evolving range of laws, regulations and standards that address information security, data protection, privacy, consent and advertising, among other things. We are also subject to laws governing marketing and advertising activities conducted by telephone, email, mobile devices, and the Internet, including the Telephone Consumer Protect Act, the Telemarketing Sales Rule, the CAN-SPAM Act, and similar state laws. In addition, some of our mortgage advertising products are operated by our wholly owned subsidiary, Zillow Group Mortgages, Inc., a licensed mortgage broker, pursuant to a support services agreement. Though we do not take mortage applications or make loans or credit decisions in connection with loans, Zillow Group Mortgages, Inc. is subject to stringent state and federal laws and regulations and to the scrutiny of state and federal government agencies as a licensed mortgage broker.

By providing a medium through which users can post content and communicate with one another, we may also be subject to laws governing intellectual property ownership, obscenity, libel, and privacy, among other issues. In addition, the real estate agents, mortgage professionals, banks, property managers, rental agents and some of our other customers and advertisers on our mobile applications and websites are subject to various state and federal laws and regulations relating to real estate, rentals and mortgages. We endeavor to ensure that any content created by Zillow is consistent with such laws and regulations by obtaining assurances of compliance from our advertisers and consumers for their activities through, and the content they provide on, our mobile applications and websites. The real estate, mortgages, and rentals industries are subject to significant state and federal regulation; though we provide advertising services and technology solutions to real estate, mortgages, and rentals professionals, certain of our activities may be deemed to be covered by these industry regulations. Since the laws and regulations governing real estate, rentals and mortgages are constantly evolving, it is possible that we may have to materially alter the way we conduct some parts of our business activities or be prohibited from conducting such activities altogether at some point in the future.

Employees

As of December 31, 2015, we had 2,204 full-time employees.

Where You Can Find More Information

Our filings with the Securities and Exchange Commission, or SEC, including our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and amendments to those reports, are available on our website at www.zillowgroup.com, free of charge, as soon as reasonably practicable after the electronic filing of these reports with the SEC. The information contained on our website is not a part of this Annual Report on Form 10-K.

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Investors and others should note that Zillow Group announces material financial information to its investors using its press releases, SEC filings and public conference calls and webcasts. Zillow Group intends to also use the following channels as a means of disclosing information about Zillow Group, its services and other matters and for complying with its disclosure obligations under Regulation FD:

The information Zillow Group posts through these channels may be deemed material. Accordingly, investors should monitor these channels, in addition to following Zillow Group’s press releases, SEC filings and public conference calls and webcasts. This list may be updated from time to time. The information we post through these channels is not a part of this Annual Report on Form 10-K.

Item 1A. Risk Factors

Our business is subject to numerous risks. You should carefully consider the following risk factors, as any of these risks could harm our business, results of operations, financial condition and our prospects. In addition, risks and uncertainties not currently known to us or that we currently deem to be immaterial also may materially adversely affect our business, financial condition and operating results.

Risks Related to the Acquisition of Trulia

We May Experience Difficulties in Realizing the Expected Benefits of the Acquisition of Trulia.

The Trulia acquisition was completed on February 17, 2015, and the integration is substantially complete as of December 31, 2015. Integration resulted in substantial financial costs and required the investment of personnel time and attention and other resources. The success of the acquisition of Trulia depends in part on our ability to realize the anticipated business opportunities, including certain cost savings and operational efficiencies or synergies, and growth prospects from combining Zillow and Trulia in an efficient and effective manner. We may never realize these business opportunities and growth prospects.

Purchase Price Accounting in Connection with our Acquisition of Trulia Requires Estimates Which Are Subject to Change in the Future. Future Changes to These Estimates Could Impact Our Condensed Consolidated Financial Statements and Our Future Operating Results.

Under the acquisition method of accounting, the purchase price paid for Trulia is allocated to the underlying Trulia tangible and intangible assets acquired and liabilities assumed based on their respective fair market values with any excess purchase price allocated to goodwill. The acquisition method of accounting is dependent upon certain valuations and other studies that are preliminary. Accordingly, the purchase price allocation as of the acquisition date is preliminary. Zillow Group anticipates that all the information needed to identify and measure values assigned to the assets acquired and liabilities assumed will be obtained and finalized during the one-year measurement period following the date of completion of the acquisition. Differences between these preliminary estimates and the final acquisition accounting may occur, and these differences could have a material impact on the consolidated financial statements and the combined company’s future results of operations and financial position.

We Have Incurred, and May Continue to Incur, Significant Acquisition-Related Costs and Transition Costs in Connection with the Acquisition of Trulia.

We have incurred, and may continue to incur, significant, non-recurring costs in connection with completing the acquisition of Trulia and integrating the operations of Zillow and Trulia. We may incur additional costs to maintain employee morale and to retain key employees. Management cannot ensure that the elimination of duplicative costs or the realization of other efficiencies will offset the transaction and integration costs in the near term or at all.

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Risks Related to Our Business and Industry

If Real Estate, Rental and Mortgage Professionals or Other Advertisers Reduce or End Their Advertising Spending With Us and We are Unable to Attract New Advertisers, Our Business Would Be Harmed.

Our current financial model depends on advertising revenue generated primarily through sales to real estate agents and brokerages, rental professionals, mortgage professionals and advertisers in categories relevant to real estate. Our ability to attract and retain advertisers, and ultimately to generate advertising revenue, depends on a number of factors, including how successfully we can:

We do not have long-term contracts with most of our advertisers. Our advertisers could choose to modify or discontinue their relationships with us with little or no advance notice. In addition, as existing contracts for our Premier Agent advertising programs expire, we may not be successful in renewing these contracts, securing new contracts or increasing the amount of revenue we earn for a given contract over time. We may not succeed in retaining existing advertisers’ spending or capturing a greater share of such spending if we are unable to convince advertisers of the effectiveness or superiority of our products as compared to alternatives, including traditional offline advertising media such as television and newspapers. In addition, future changes to our pricing methodology for advertising services may cause advertisers to reduce their advertising with us or choose not to advertise with us.

If current advertisers reduce or end their advertising spending with us and we are unable to attract new advertisers, our advertising revenue and business, results of operations and financial condition would be harmed. In addition, if we do not realize the benefits we expect from strategic relationships we enter into, including for example, the generation of additional advertising revenue opportunities, our business could be harmed.

If We Do Not Innovate and Provide Products and Services That Are Attractive to Our Users and to Our Advertisers, Our Business Could Be Harmed.

Our success depends on our continued innovation to provide products and services that make our mobile applications, websites and other tools useful for consumers and real estate, rental, mortgage and home improvement professionals, and attractive to our advertisers. As a result, we must continually invest significant resources in research and development to improve the attractiveness and comprehensiveness of our products and services and effectively incorporate new mobile and Internet technologies into them. If we are unable to provide products and services that users, including real estate professionals, want to use, then users may become dissatisfied and use competitors’ mobile applications, websites and tools. If we are unable to continue offering innovative products and services, we may be unable to attract additional users and advertisers or retain our current users and advertisers, which could harm our business, results of operations and financial condition.

If Use of Mobile Technology and the Internet, Particularly With Respect to Real Estate Products and Services, Does Not Continue to Increase as Rapidly as We Anticipate, Our Business Could Be Harmed.

Our future success substantially depends on the continued use of mobile technology and the Internet as effective media of business and communication by our consumers. Mobile technology and Internet use may not continue to develop at historical rates, and consumers may not continue to use mobile technology or the Internet

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as media for information exchange. Further, these media may not be accepted as viable long-term outlets for information for a number of reasons, including actual or perceived lack of security of information and possible disruptions of service or connectivity. If consumers begin to access real estate information through other media and we fail to innovate, our business may be negatively impacted.

We Compete in a Dynamic and Nascent Industry, and We May Invest Significant Resources to Pursue Strategies That Do Not Prove Effective.

The industry for residential real estate information marketplaces and related advertising services on mobile and Web is in early stages of development, and significant shifts in consumer and professional behaviors occur constantly and rapidly. We continue to learn a great deal about the behaviors and objectives of residential real estate market participants as the industry evolves. We may not successfully anticipate or keep pace with industry changes, and we may invest considerable financial, personnel, and other resources to pursue strategies that do not, ultimately, prove effective such that our results of operations and financial condition may be harmed.

We Depend on the Real Estate Industry, and Changes to That Industry, or Declines in the Real Estate Market or Increases in Mortgage Interest Rates, Could Reduce the Demand for Our Products and Services.

Our financial results significantly depend on real estate shoppers using our services. Real estate shopping patterns depend on the overall health of the real estate market. Changes to the regulation of the real estate industry, including mortgage lending, may negatively impact the prevalence of home ownership and the ability of market participants to close transactions. Changes to the real estate industry, declines in the real estate market or increases in mortgage interest rates could reduce demand for our services. Real estate markets also may be negatively impacted by a significant natural disaster, such as earthquake, fire, flood or other disruption. In addition, real estate, rental, and mortgage professionals are subject to comprehensive federal, state, and local laws and regulations which may cause them to significantly alter, decrease, or terminate their purchase of our products and services. Seasonality, micro- and macroeconomic factors, government regulation, and other similar factors may decrease consumer usage as well as sales to our advertisers and other customers, which could harm our results of operations and financial condition.

We May Not Be Able to Maintain or Establish Relationships With Real Estate Brokerages, Real Estate Listing Aggregators, Multiple Listing Services, Property Management Companies, Home Builders and Other Third-Party Listing Providers, Which Could Limit the Information We Are Able to Provide to Our Users.

Our ability to attract users to our mobile applications, websites and other tools depends to some degree on providing a robust number of for-sale and rental listings. To provide these listings, we maintain relationships with real estate brokerages, real estate listing aggregators, multiple listing services, property management companies, home builders, other third-party listing providers, and homeowners and their real estate agents to include listing data in our services. Many of our agreements with real estate listing providers are short-term agreements that may be terminated with limited notice. The loss of some of our existing relationships with listing providers, whether due to termination of agreements or otherwise, changes to our rights to use listing data, or an inability to continue to add new listing providers, may cause our listing data to omit information important to users of our products and services. This could reduce user confidence in the sale and rental data we provide and make us less popular with consumers, which could harm our business, results of operations and financial condition.

Historically, a substantial portion of the listings displayed on our mobile applications and websites was provided to us by a single real estate listing aggregator pursuant to platform services agreements. These listings provided revenue-generating opportunities as impressions were delivered through our mobile applications and websites. Pursuant to agreements with the real estate listing aggregator, the platform services agreements expired on April 7, 2015. Through various data acquisition efforts, including the January 2015 launch of the Zillow Data Dashboard, a new listing management and reporting platform that allows Multiple Listing Services, or MLSs, and brokers to provide listings directly to Zillow, we have made progress in replacing the listings previously

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provided under the platform services agreements. Since January 2015, nearly 400 MLSs have signed agreements to send listings directly to Zillow and Trulia. However, we may not be able to fully replace the listings in a timely manner or on terms favorable to us, if at all, which could harm our business, results of operations and financial condition.

We May Not Be Able to Maintain or Establish Relationships With Data Providers, Which Could Limit the Information We Are Able to Provide to Our Users and Impair Our Ability to Attract or Retain Users.

We obtain real estate data, such as sale transactions, property descriptions, tax-assessed value and property taxes paid, under licenses from third-party data providers. We use this data to enable the development, maintenance and improvement of our information services, including Zestimates, Rent Zestimates and our living database of homes. We have invested significant time and resources to develop proprietary algorithms, valuation models, software and practices to use and improve on this specific data. We may be unable to renew our licenses with these data providers, or we may be able to do so only on terms that are less favorable to us, which could harm our ability to continue to develop, maintain and improve these information services and could harm our business, results of operations and financial condition.

We Face Competition to Attract Consumers to Our Mobile Applications and Websites, Which Could Impair Our Ability to Continue to Grow the Number of Users Who Use Our Mobile Applications and Websites, Which Would Harm Our Business, Results of Operations and Financial Condition.

Our success depends on our ability to continue to attract additional consumers to our mobile applications and websites. Our existing and potential competitors include companies that operate, or could develop, national and local real estate, rental, mortgage and home improvement websites. These companies could devote greater technical and other resources than we have available, have a more accelerated time frame for deployment and leverage their existing user bases and proprietary technologies to provide products and services that consumers might view as superior to our offerings. Any of our future or existing competitors may introduce different solutions that attract consumers or provide solutions similar to our own but with better branding or marketing resources. If we are not able to continue to grow the number of consumers who use our mobile applications and websites, our business, results of operations and financial condition would be harmed.

We May Not Be Able to Compete Successfully Against Our Existing or Future Competitors in Attracting Advertisers, Which Could Harm Our Business, Results of Operations and Financial Condition.

We compete to attract advertisers with media sites, including websites dedicated to providing real estate, rental, mortgage and home improvement information and services to real estate professionals and consumers, and major Internet portals, general search engines and social media sites, as well as other online companies. We also compete for a share of advertisers’ overall marketing budgets with traditional media such as television, magazines, newspapers and home/apartment guide publications, particularly with respect to advertising dollars spent at the local level by real estate professionals to advertise their qualifications and listings. Large companies with significant brand recognition have large numbers of direct sales personnel and substantial proprietary advertising inventory and web traffic, which may provide a competitive advantage. To compete successfully for advertisers against future and existing competitors, we must continue to invest resources in developing our advertising platform and proving the effectiveness and relevance of our advertising products and services. Pressure from competitors seeking to acquire a greater share of our advertisers’ overall marketing budget could adversely affect our pricing and margins, lower our revenue, and increase our research and development and marketing expenses. If we are unable to compete successfully against our existing or future competitors, our business, results of operations or financial condition would be harmed.

Our Dedication to Making Decisions Based Primarily on the Best Interests of Consumers May Cause Us to Forgo Short-Term Gains.

Our guiding principle is to build our business by making decisions based primarily on the best interests of consumers, which we believe has been essential to our success in increasing our user growth rate and

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engagement and has served the long-term interests of our company and our shareholders. In the past, we have forgone, and we will in the future forgo, certain expansion or short-term revenue opportunities that we do not believe are in the best interests of consumers, even if such decisions negatively impact our short-term results of operations. In addition, our philosophy of putting consumers first may negatively impact our relationships with our existing or prospective advertisers. This could result in a loss of advertisers, which could harm our revenue and results of operations. For example, we believe that some real estate agents have chosen not to purchase our Premier Agent product because we display a Zestimate on their for-sale listings. We believe, however, that it is valuable to consumers to have access to a valuation starting point on all homes and so we display a Zestimate on every home in the Zillow database for which we have sufficient data to produce the Zestimate. Similarly, we gather, and make available to our consumers, reviews on real estate, rental, mortgage and home improvement professionals, even if those reviews are unfavorable. Although real estate, rental, mortgage and home improvement professionals who receive unfavorable reviews may be less likely to purchase our advertising products and services, we continue to post favorable and unfavorable reviews because we believe the reviews are useful to consumers in finding the right professional. Our principle of making decisions based primarily on the best interests of consumers may not result in the long-term benefits that we expect, in which case our user traffic and engagement, business and results of operations could be harmed.

We May in the Future Be Subject to Disputes Regarding the Accuracy of Our Zestimates and Rent Zestimates.

We provide our users with Zestimate and Rent Zestimate home and rental valuations. Zestimates are our estimated current market values of a home based on our proprietary automated valuation models that apply advanced algorithms to analyze our data; they are not appraisals. A Rent Zestimate is our estimated current monthly rental price of a home, using similar automated valuation models that we have designed to address the unique attributes of rental homes. Revisions to our automated valuation models, or the algorithms that underlie them, may cause certain Zestimates or Rent Zestimates to vary from our expectations for those Zestimates or Rent Zestimates. In addition, from time to time, users disagree with our Zestimates and Rent Zestimates. Any such variation in Zestimates or Rent Zestimates or disagreements could result in distraction from our business or potentially harm our reputation and could result in legal disputes.

We May Be Unable to Increase Awareness of the Zillow Group Brands Cost-effectively, Which Could Harm Our Business.

We rely heavily on the Zillow Group brands, including Zillow and Trulia, which we believe are key assets of our company. Awareness and perceived quality and differentiation of the Zillow Group brands are important aspects of our efforts to attract and expand the number of consumers who use our mobile applications and websites. Should the competition for awareness and brand preference increase among providers of mobile or online real estate information, we may not be able to successfully maintain or enhance the strength of our brand. In 2013 and 2014, we significantly increased our advertising investment to increase brand awareness and grow traffic, and this investment continued through 2015. We expect to continue to invest in our paid advertising. Paid advertising may not continue to be successful or cost-effective. If we are unable to maintain or enhance user and advertiser awareness of our brand cost-effectively, or if we are unable to recover our additional marketing and advertising costs through increased usage of our products and services, our business, results of operations and financial condition could be harmed.

If We Fail to Manage Our Growth Effectively, Our Brands, Results of Operations and Business Could Be Harmed.

We have experienced rapid and significant growth in our headcount and operations, including as a result of the February 2015 Trulia acquisition, which places substantial demand on management and our operational infrastructure. The majority of our employees have been with us for fewer than two years. As we continue to grow, we must effectively integrate, develop and motivate a large number of new employees, while maintaining the beneficial aspects of our company culture. In particular, we expect to continue to pursue strategic

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opportunities and make substantial investments in our technology and development and sales and marketing organizations. If we do not manage the growth of our business and operations effectively, the quality of our services and efficiency of our operations could suffer, which could harm our brand, results of operations and overall business.

We Rely on the Performance of Highly Skilled Personnel, and if We Are Unable to Attract, Retain and Motivate Well-Qualified Employees, Our Business Could Be Harmed.

We believe our success has depended, and continues to depend, on the efforts and talents of our management and our highly skilled team of employees, including our software engineers, statisticians, marketing professionals and advertising sales staff. Our future success depends on our continuing ability to attract, develop, motivate and retain highly qualified and skilled employees. The loss of any of our senior management or key employees could materially adversely affect our ability to build on the efforts they have undertaken and to execute our business plan, and we may not be able to find adequate replacements. We cannot ensure that we will be able to retain the services of any members of our senior management or other key employees. If we do not succeed in attracting well-qualified employees or retaining and motivating existing employees, our business could be harmed.

We May Make Acquisitions and Investments, Which Could Result in Operating Difficulties, Dilution and Other Harmful Consequences.

We continue to evaluate a wide array of potential strategic opportunities, including acquisitions. Any transactions that we enter into could be material to our financial condition and results of operations. The acquisitions may not result in the intended benefits to our business, and we may not successfully evaluate or utilize the acquired products, technology, or personnel, or accurately forecast the financial impact of an acquisition transaction. The process of integrating an acquired company, business or technology could create unforeseen operating difficulties and expenditures. The areas where we face risks include:

Our failure to address these risks or other problems encountered in connection with our past or future acquisitions and investments could cause us to fail to realize the anticipated benefits of such acquisitions or investments, incur unanticipated liabilities, and harm our business, results of operations and financial condition.

We Are Subject to a Number of Risks Related to the Credit Card and Debit Card Payments We Accept.

We accept payments through credit and debit card transactions. For credit and debit card payments, we pay interchange and other fees, which may increase over time. An increase in those fees may require us to increase the prices we charge and would increase our operating expenses, either of which could harm our business, financial condition and results of operations.

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We depend on processing vendors to complete credit and debit card transactions. If we or our processing vendors fail to maintain adequate systems for the authorization and processing of credit card transactions, it could cause one or more of the major credit card companies to disallow our continued use of their payment products. In addition, if these systems fail to work properly and, as a result, we do not charge our customers’ credit cards on a timely basis or at all, our business, revenue, results of operations and financial condition could be harmed.

We are also subject to payment card association operating rules, certification requirements and rules governing electronic funds transfers, which could change or be reinterpreted to make it more difficult for us to comply. We are required to comply with payment card industry security standards. Failing to comply with those standards may violate payment card association operating rules, federal and state laws and regulations, and the terms of our contracts with payment processors. Any failure to comply fully also may subject us to fines, penalties, damages and civil liability, and may result in the loss of our ability to accept credit and debit card payments. Further, there is no guarantee that such compliance will prevent illegal or improper use of our payment systems or the theft, loss, or misuse of data pertaining to credit and debit cards, card holders and transactions.

If we fail to adequately control fraudulent credit card transactions, we may face civil liability, diminished public perception of our security measures, and significantly higher credit card-related costs, each of which could harm our business, results of operations and financial condition.

If we are unable to maintain our chargeback rate or refund rates at acceptable levels, our processing vendors may increase our transaction fees or terminate their relationships with us. Any increases in our credit and debit card fees could harm our results of operations, particularly if we elect not to raise our rates for our service to offset the increase. The termination of our ability to process payments on any major credit or debit card would significantly impair our ability to operate our business.

Risks Related to Our Intellectual Property and Technology

If Our Security Measures Are Compromised, We May Be Subject to Legal Claims and Suffer Significant Losses, and Consumers May Curtail Use of Our Products and Services and Advertisers May Reduce Their Advertising on Our Mobile Applications and Websites.

Our products and services involve the transmission and/or storage of users’ information, some of which may be private or include personally identifiable information such as social security numbers and credit card information, and security breaches could expose us to a risk of loss or exposure of this information, which could result in potential liability and litigation. Like all mobile application and website providers, our mobile applications and websites are vulnerable to computer viruses, break-ins, phishing attacks, attempts to overload our servers with denial-of-service or other attacks, and similar disruptions from unauthorized use of our computer systems, any of which could lead to interruptions, delays, or website shutdowns, causing loss of critical data or the unauthorized disclosure or use of personal or other confidential information. Further, outside parties may attempt to fraudulently induce employees, users or advertisers to disclose sensitive information in order to gain access to our information or our users’ or advertisers’ information, and our information technology and infrastructure may be vulnerable to attacks by hackers or breached due to employee error, malfeasance or other disruptions. If we experience compromises to our security that result in mobile application or website performance or availability problems, the complete shutdown of our mobile applications or websites, or the loss or unauthorized disclosure of confidential information, our users and advertisers may lose trust and confidence in us, we may be subject to legal claims, government investigation and additional state and federal statutory requirements, users may decrease the use of our mobile applications or websites or stop using our mobile applications or websites in their entirety, and advertisers may decrease or stop advertising on our mobile applications or websites. In May 2015, for example, we detected a distributed denial of service attack against our website, zillow.com. Upon detection, standard response protocols were immediately initiated, filtering malicious

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traffic and restoring network performance. This incident did not have a material adverse effect on our business, and there is no indication that our internal controls were compromised. Despite the additional network detection tools we implemented, we cannot ensure that we will not experience future incidents.

We depend on data storage vendors to store certain user information, some of which may be private or include personally identifiable information. If our data storage vendors fail to maintain adequate information security systems and our users’ information is compromised, our business, results of operations and financial condition could be harmed.

Further, because the techniques used to obtain unauthorized access, disable or degrade service, or sabotage systems change frequently, often are not recognized until launched against a target, and may originate from less regulated and remote areas around the world, we may be unable to proactively address all these techniques or to implement adequate preventative measures. Any or all of these issues could negatively impact our ability to attract new users and increase engagement by existing users, cause existing users to curtail or stop use of our products or services or close their accounts, cause existing advertisers to cancel their contracts, or subject us to third-party lawsuits, regulatory fines or other action or liability, thereby harming our business, results of operations and financial condition.

Any Significant Disruption in Service on Our Mobile Applications or Websites or in Our Network Could Damage Our Reputation and Brands, and Result in a Loss of Users of Our Products and Services and of Advertisers, Which Could Harm Our Business, Results of Operations and Financial Condition.

Our brand, reputation and ability to attract users and advertisers depend on the reliable performance of our network infrastructure and content delivery processes. We have experienced minor interruptions in these systems in the past, including server failures that temporarily slowed the performance of our mobile applications and websites, and we may experience interruptions in the future. Interruptions in these systems, whether due to system failures, computer viruses, software errors or physical or electronic break-ins, could affect the security or availability of our products and services on our mobile applications and websites and prevent or inhibit the ability of users to access our services. Since our users may rely on our products and services, including our free customer relationship management tools, for important aspects of their businesses, problems with the reliability, availability or security of our systems could damage our users’ businesses, harm our reputation, result in a loss of users of our products and services and of advertisers and result in additional costs, any of which could harm our business, results of operations and financial condition.

The majority of the communications, network and computer hardware used to operate our mobile applications and websites are located at facilities in the Seattle, Washington and Santa Clara, California areas. We do not own or control the operation of certain of these facilities. Our systems and operations are vulnerable to damage or interruption from fire, flood, power loss, telecommunications failure, terrorist attacks, acts of war, electronic and physical break-ins, computer viruses, earthquakes and similar events. The occurrence of any of the foregoing events could result in damage to our systems and hardware or could cause them to fail completely, and our insurance may not cover such events or may be insufficient to compensate us for losses that may occur.

A failure of our systems at one site could result in reduced functionality for our users, and a total failure of our systems could cause our mobile applications or websites to be inaccessible. Problems faced by our third-party web-hosting providers with the telecommunications network providers with which they contract or with the systems by which they allocate capacity among their customers, including us, could adversely affect the experience of our users. Our third-party web-hosting providers could decide to close their facilities without adequate notice. Any financial difficulties, such as bankruptcy reorganization, faced by our third-party web-hosting providers or any of the service providers with whom they contract may have negative effects on our business, the nature and extent of which are difficult to predict. If our third-party web-hosting providers are unable to keep up with our growing needs for capacity, our business could be harmed. In addition, if distribution channels for our mobile applications experience disruptions, such disruptions could adversely affect the ability of users and potential users to access or update our mobile applications, which could harm our business.

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We do not carry business interruption insurance sufficient to compensate us for the potentially significant losses, including the potential harm to the future growth of our business, which may result from interruptions in our service as a result of system failures. Any errors, defects, disruptions or other performance problems with our services could harm our reputation, business, results of operations and financial condition.

We May Be Unable to Adequately Protect Our Intellectual Property, Which Could Harm the Value of Our Brands and Our Business.

We regard our intellectual property as critical to our success, and we rely on trademark, copyright and patent law, trade secret protection and contracts to protect our proprietary rights. If we are not successful in protecting our intellectual property, the value of our brands and our business, results of operations and financial condition could be harmed.

While we believe that our issued patents and pending patent applications help to protect our business, we cannot ensure that our operations do not, or will not, infringe valid, enforceable patents of third parties or that competitors will not devise new methods of competing with us that are not covered by our patents or patent applications. We cannot ensure that our patent applications will be approved, that any patents issued will adequately protect our intellectual property, that such patents will not be challenged by third parties or found to be invalid or unenforceable, or that our patents will be effective in preventing third parties from utilizing a “copycat” business model to offer the same products or services. Moreover, we rely on intellectual property and technology developed or licensed by third parties, and we may not be able to obtain licenses and technologies from these third parties on reasonable terms or at all.

Effective trademark, service mark, copyright and trade secret protection may not be available in every country in which our products and services may be provided. The laws of certain countries do not protect proprietary rights to the same extent as the laws of the United States and, therefore, in certain jurisdictions, we may be unable to protect intellectual property and our proprietary technology adequately against unauthorized third-party copying or use, which could harm our competitive position. We have licensed in the past, and expect to license in the future, certain of our proprietary rights, such as trademarks or copyrighted material, to third parties. These licensees may take actions that might diminish the value of our proprietary rights or harm our reputation, even if we have agreements prohibiting such activity. To the extent third parties are obligated to indemnify us for breaches of our intellectual property rights, these third parties may be unable to meet these obligations. Any of these events could harm our business, results of operations or financial condition.

In addition, we may actively pursue entities that infringe our intellectual property, including through legal action. Taking such action may be costly, and we cannot ensure that such actions will be successful. Any increase in the unauthorized use of our intellectual property could make it more expensive for us to do business and harm our results of operations or financial condition.

Intellectual Property Disputes Are Costly to Defend and Could Harm Our Business, Results of Operations, Financial Condition and Reputation.

From time to time, we face allegations that we have infringed the trademarks, copyrights, patents and other intellectual property rights of third parties. We are currently subject to patent and other intellectual properly infringement claims. These claims allege, among other things, that aspects of our technology infringe upon the plaintiffs’ patents or other intellectual property. If we are not successful in defending ourselves against these claims, we may be required to pay damages and may be subject to injunctions, each of which could harm our business, results of operations, financial condition and reputation. We may be subject to future claims or allegations relating to our intellectual property rights. As we grow our business and expand our operations, we expect that we will continue to be subject to intellectual property claims and allegations. Patent and other intellectual property disputes or litigation may be protracted and expensive, and the results are difficult to predict and may require us to stop offering certain products, services or features, purchase licenses that may be

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expensive to procure, or modify our products or services. In addition, patent or other intellectual property disputes or litigation may result in significant settlement costs. Any of these events could harm our business, results of operations, financial condition and reputation.

In addition, we use open source software in our services and will continue to use open source software in the future. From time to time, we may be subject to claims brought against companies that incorporate open source software into their products or services, claiming ownership of, or demanding release of, the source code, the open source software and/or derivative works that were developed using such software, or otherwise seeking to enforce the terms of the applicable open source license. These claims could also result in litigation, require us to purchase a costly license, or require us to devote additional research and development resources to changing our products or services, any of which would have a negative effect on our business and results of operations.

Even if these matters do not result in litigation or are resolved in our favor or without significant cash settlements, the time and resources necessary to resolve them could harm our business, results of operations, financial condition and reputation.

We May Be Unable to Continue to Use the Domain Names That We Use in Our Business, or Prevent Third Parties From Acquiring and Using Domain Names That Infringe on, Are Similar to, or Otherwise Decrease the Value of Our Brand or Our Trademarks or Service Marks.

We have registered domain names for our websites that we use in our business. If we lose the ability to use a domain name, we may incur significant expenses to market our products and services under a new domain name, which could harm our business. In addition, our competitors could attempt to capitalize on our brand recognition by using domain names similar to ours. Domain names similar to ours have been registered in the United States and elsewhere. We may be unable to prevent third parties from acquiring and using domain names that infringe on, are similar to, or otherwise decrease the value of our brand or our trademarks or service marks. Protecting and enforcing our rights in our domain names and determining the rights of others may require litigation, which could result in substantial costs and diversion of management’s attention.

Confidentiality Agreements With Employees and Others May Not Adequately Prevent Disclosure of Trade Secrets and Other Proprietary Information.

In order to protect our technologies and processes, we rely in part on confidentiality agreements with our employees, licensees, independent contractors and other advisors. These agreements may not effectively prevent disclosure of confidential information, including trade secrets, and may not provide an adequate remedy in the event of unauthorized disclosure of confidential information. In addition, others may independently discover our trade secrets and proprietary information, and in such cases we could not assert any trade secret rights against such parties. To the extent that our employees, contractors or other third parties with whom we do business use intellectual property owned by others in their work for us, disputes may arise as to the rights in related or resulting know-how and inventions. The loss of trade secret protection could make it easier for third parties to compete with our products by copying functionality. In addition, any changes in, or unexpected interpretations of, intellectual property laws may compromise our ability to enforce our trade secret and intellectual property rights. Costly and time-consuming litigation could be necessary to enforce and determine the scope of our proprietary rights, and failure to obtain or maintain protection of our trade secrets or other proprietary information could harm our business, results of operations, reputation and competitive position.

We May Not Be Able to Halt the Operations of Websites That Aggregate or Misappropriate Our Data.

From time to time, third parties have misappropriated our data through website scraping, robots or other means, and aggregated this data on their websites with data from other companies. In addition, copycat websites have misappropriated data on our network and attempted to imitate our brand or the functionality of our websites. When we have become aware of such websites, we have employed technological or legal measures in an attempt to halt their operations. We may not be able, however, to detect all such websites in a timely manner and, even if

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we could, technological and legal measures may be insufficient to halt their operations. In some cases, particularly in the case of websites operating outside of the United States, our available remedies may not be adequate to protect us against the impact of the operation of such websites. Regardless of whether we can successfully enforce our rights against the operators of these websites, any measures that we may take could require us to expend significant financial or other resources, which could harm our business, results of operations or financial condition. In addition, to the extent that such activity creates confusion among consumers or advertisers, our brands and business could be harmed.

Risks Related to Regulatory Compliance and Legal Matters

We Are, and May in the Future Become, Subject to a Variety of Federal and State Laws, Many of Which Are Unsettled and Still Developing and Which Could Subject Us to Claims or Otherwise Harm Our Business.

We are currently subject to a variety of, and may in the future become subject to additional, federal and state laws that are continuously evolving and developing, including laws regarding the real estate, rental, mortgage and home improvement industries, mobile- and Internet-based businesses and other businesses that rely on advertising, as well as privacy and consumer protection laws, including the Telephone Consumer Protect Act, the Telemarketing Sales Rule, the CAN-SPAM Act, and similar state laws. These laws can be costly to comply with, require significant management time and effort, and subject us to claims, government enforcement actions, civil and criminal liability or other remedies, including suspension of business operations. These laws may conflict with each other, and if we comply with the laws of one jurisdiction, we may find that we are violating laws of another jurisdiction. Additionally, our ability to provide a specific target audience to advertisers is a significant competitive advantage. Any legislation reducing this ability would have a negative impact on our business and results of operations.

If we are unable to comply with these laws or regulations, if we become liable under these laws or regulations, or if unfavorable regulations or unfavorable interpretations of existing regulations by courts or regulatory bodies are implemented, we could be directly harmed and forced to implement new measures to reduce our exposure to this liability and it could cause the development of product or service offerings in affected markets to become impractical. This may require us to expend substantial resources or to discontinue certain products or services, limit our ability to expand our product and services offerings, or expand into new markets or otherwise harm our business, results of operations and financial condition. In addition, the increased attention focused on liability issues as a result of lawsuits and legislative proposals could harm our reputation or otherwise impact the growth of our business. Any costs incurred as a result of this potential liability could harm our business and results of operations.

We assist with the processing of customer credit card transactions and consumer credit report requests, which results in us receiving personally identifiable information. This information is increasingly subject to legislation and regulation in the United States. This legislation and regulation is generally intended to protect the privacy and security of personal information, including credit card information that is collected, processed and transmitted. We could be adversely affected if government regulations require us to significantly change our business practices with respect to this type of information.

Certain of our mortgage advertising products are operated by our wholly owned subsidiary, Zillow Group Mortgages, Inc., a licensed mortgage broker, pursuant to a support services agreement. Though we do not take mortage applications or make loans or credit decisions in connection with loans, Zillow Group Mortgages, Inc. is subject to stringent state and federal laws and regulations and to the scrutiny of state and federal government agencies as a licensed mortgage broker. Further, due to the geographic scope of our operations and the nature of the services we provide, we may be required to obtain and maintain additional real estate brokerage and mortgage broker licenses in certain states in which we operate. In connection with such licenses, we are required to designate individual licensed brokers of record. We cannot assure you that we are, and will remain at all times, in full compliance with state real estate and mortgage broker licensing laws and regulations and we may be subject to fines or penalties in the event of any non-compliance. If in the future a state agency were to determine

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that we are required to obtain a real estate or mortgage brokerage license in that state in order to receive payments or commissions from real estate professionals, or if we lose an existing license or are otherwise found to be in violation of a law or regulation, we may be subject to fines or legal penalties or our business operations in that state may be suspended until we obtain the license or otherwise remedy the compliance issue. Any failure to comply with applicable laws and regulations may limit our ability to expand into new markets, offer new products or continue to operate in one or more of our current markets.

We are From Time to Time Involved In, or May In the Future be Subject to, Claims, Suits, Government Investigations, and Other Proceedings That May Result In Adverse Outcomes.

We are from time to time involved in, or may in the future be subject to, claims, suits, government investigations, and proceedings arising from our business, including actions with respect to intellectual property claims, privacy, consumer protection, information security, data protection or law enforcement matters, tax matters, labor and employment claims, commercial claims, as well as actions involving content generated by our users, shareholder derivative actions, purported class action lawsuits, and other matters, including for example, the compliance review by the Wage and Hour Division of the U.S. Department of Labor described below in Part I, Item 3. Such claims, suits, government investigations, and proceedings are inherently uncertain and their results cannot be predicted with certainty. Regardless of the outcome, any such legal proceedings can have an adverse impact on us because of legal costs, diversion of management and other personnel, and other factors. For instance, for the fiscal year ended December 31, 2015, we incurred approximately $27.1 million in legal costs related to our litigation with Move, Inc., described below in Part I, Item 3. In addition, it is possible that a resolution of one or more such proceedings could result in reputational harm, liability, penalties, or sanctions, as well as judgments, consent decrees, or orders preventing us from offering certain features, functionalities, products, or services, or requiring a change in our business practices, products or technologies, which could in the future materially and adversely affect our business, operating results and financial condition. As an example, in connection with our litigation with Move, Inc., described below in Part I, Item 3, the plaintiffs recently indicated that they are seeking damages which, if actually awarded, would have a material adverse effect on our business, operating results and financial condition. See “Legal Proceedings” below in Part I, Item 3.

The Requirements of Being a Public Company May Strain Our Resources and Distract Our Management, Which Could Make It Difficult to Manage Our Business.

We are required to comply with various regulatory and reporting requirements, including those required by the SEC. Complying with these reporting and other regulatory requirements can be time-consuming and results in increased costs to us and could harm our business, results of operations and financial condition.

As a public company, we are subject to the reporting requirements of the Securities Exchange Act of 1934, as amended, or the Exchange Act. These requirements could strain our systems and resources. The Exchange Act also requires that we file annual, quarterly and current reports with respect to our business and financial condition. The Exchange Act requires that we maintain effective disclosure controls and procedures and internal control over financial reporting. To maintain and improve the effectiveness of our disclosure controls and procedures and internal control over financial reporting, we have committed significant resources, hired additional staff and provided additional management oversight. We have implemented additional procedures and processes for the purpose of addressing the standards and requirements applicable to public companies. Sustaining our growth will require us to commit additional management, operational and financial resources to identify new professionals to join us and to maintain appropriate operational and financial systems to adequately support expansion. These activities may divert management’s attention from other business concerns and could make it difficult to manage our business, which could harm our business, results of operations, financial condition and cash flows. In addition, if we identify any material weaknesses in our internal controls, we could lose investor confidence in the accuracy and completeness of our financial reports, which would cause the market price of our capital stock to decline.

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Risks Related to Our Financial Statements

We Incurred Significant Operating Losses in the Past and We May Not Be Able to Generate Sufficient Revenue to Be Profitable Over the Long Term.

We have incurred significant net operating losses in the past and, as of December 31, 2015, we had an accumulated deficit of $276.6 million. Although we have experienced significant growth in revenue, our revenue growth rate may decline in the future as the result of a variety of factors, including the maturation of our business. At the same time, we also expect our costs to increase in future periods as we continue to expend substantial financial resources to develop and expand our business, including on:

These investments may not result in increased revenue or growth in our business. If we fail to continue to grow our revenue and overall business and to manage our expenses, we may incur significant losses in the future and not be able to maintain profitability.

We Rely on Assumptions and Estimates to Calculate Certain of our Key Growth Drivers, and Real or Perceived Inaccuracies in Such Metrics May Harm our Reputation and Negatively Affect our Business.

Our key metrics of unique users and Agent Advertisers are calculated using internal company data that has not been independently verified. While these numbers are based on what we believe to be reasonable calculations for the applicable period of measurement, there are inherent challenges in measuring such information. For example, our measurement of unique users may be affected by applications that automatically contact our servers to access our mobile applications and websites with no user action involved, and this activity can cause our system to count the user associated with such a device as a unique user on the day such contact occurs.

We regularly review and may adjust our processes for calculating our key growth drivers to improve their accuracy. Our measures of unique users and Agent Advertisers may differ from estimates published by third parties or from similarly-titled metrics of our competitors due to differences in methodology. If real estate professionals, advertisers or investors do not perceive our key growth drivers to be accurate representations of our user or advertiser engagement, or if we discover material inaccuracies in our key growth drivers, our reputation may be harmed, and real estate professionals and advertisers may be less willing to allocate their resources to our products and services, which could negatively affect our business and operating results.

We Expect Our Results of Operations to Fluctuate on a Quarterly and Annual Basis.

Our revenue and results of operations could vary significantly from period to period and may fail to match expectations as a result of a variety of factors, some of which are outside our control. The other risk factors discussed in this “Risk Factors” section may contribute to the variability of our quarterly and annual results. In addition, our results may fluctuate as a result of fluctuations in the quantity of, and the price at which we are able to sell, our remnant advertising, seasonal variances of home sales, which historically peak in the spring and summer seasons, and the size and seasonal variability of our advertisers’ marketing budgets. As a result of the potential variations in our revenue and results of operations, period-to-period comparisons may not be meaningful and the results of any one period should not be relied on as an indication of future performance. In addition, our results of operations may not meet the expectations of investors or public market analysts who follow us, which may adversely affect our stock price.

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Our Ability to Use Our Net Operating Loss Carryforwards and Certain Other Tax Attributes May Be Limited.

As of December 31, 2015, we had federal net operating loss carryforwards of approximately $735.2 million, state net operating loss carryforwards of approximately $11.6 million (tax effected), and net tax credit carryforwards of approximately $17.2 million. Under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, if a corporation undergoes an “ownership change,” the corporation’s ability to use its pre-change net operating loss carryforwards and other pre-change tax attributes, such as research tax credits, to offset its post-change income or income tax liability may be limited. In general, an “ownership change” will occur if there is a cumulative change in our ownership by certain “5-percent shareholders” that exceeds 50 percentage points over a rolling three-year period. In connection with Zillow’s August 2013 public offering of Zillow Class A Common stock, Zillow experienced an ownership change that triggered Section 382 and 383, which may limit our ability to utilize net operating loss and tax credit carryforwards. In connection with Zillow Group’s February 2015 acquisition of Trulia, Trulia experienced an ownership change that triggered Section 382 and 383, which may limit Zillow Group’s ability to utilize Trulia’s net operating loss and tax credit carryforwards. If we experience one or more ownership changes in the future as a result of future transactions in our stock, our ability to utilize net operating loss carryforwards could be limited. Furthermore, our ability to utilize net operating loss carryforwards of any companies that we have acquired or may acquire in the future may be limited. As a result, if we earn net taxable income, our ability to use our pre-change net operating loss carryforwards, other pre-change tax attributes, or net operating loss carryforwards of any acquired companies to offset our federal taxable income or reduce our federal income tax liability may be subject to limitation.

Risks Related to Ownership of Our Common and Capital Stock

Our Class A Common Stock and Class C Capital Stock Prices May Be Volatile, and the Value of an Investment in Our Class A Common Stock and Class C Capital Stock May Decline.

An active, liquid and orderly market for our Class A common stock and Class C capital stock may not be sustained, which could depress the trading price of our Class A common stock and Class C capital stock. The trading price of our Class A common stock and Class C capital stock has at times experienced price volatility and may continue to be volatile. For example, since shares of our Class A common stock began trading in February 2015, the closing price of our Class A common stock has ranged from $22.58 per share to $39.13 per share (adjusted for the Class C Stock Split (as defined below)) through December 31, 2015. Since shares of our Class C capital stock began trading in August 2015, the closing price of our Class C capital stock has ranged from $23.27 per share to $33.45 per share through December 31, 2015. The market price of our Class A common stock and Class C capital stock could be subject to wide fluctuations in response to many of the risk factors discussed in this Annual Report on Form 10-K and others beyond our control, including:

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Furthermore, the stock markets in recent years have experienced extreme price and volume fluctuations that have affected and continue to affect the market prices of the equity securities of many companies. These fluctuations often have been unrelated or disproportionate to the operating performance of those companies. These broad market and industry fluctuations, as well as general economic, political and market conditions such as recessions, interest rate changes or international currency fluctuations, may negatively impact the market price of our Class A common stock and Class C capital stock. In the past, companies that have experienced volatility in the market price of their stock have been subject to securities class action litigation. We have in the past been the target of this type of litigation, and we may continue to be the target of this type of litigation in the future. Past and future securities litigation against us could result in substantial costs and divert management’s attention from other business concerns, which could harm our business, results of operations or financial condition.

The Structure of Our Capital Stock as Contained in Our Charter Documents Has the Effect of Concentrating Voting Control With Our Founders, and Limits Your Ability to Influence Corporate Matters.

Since Zillow Group’s inception, our capital structure has included authorized Class A common stock and authorized Class B common stock. Our Class A common stock entitles its holder to one vote per share, and our Class B common stock entitles its holder to 10 votes per share. All shares of Class B common stock have been and are held or controlled by our founders, Richard Barton and Lloyd Frink. As of December 31, 2015, Mr. Barton’s holdings and Mr. Frink’s holdings represented approximately 32.6% and 21.3%, respectively, of the voting power of our outstanding capital stock.

For the foreseeable future, Mr. Barton and Mr. Frink will therefore have significant control over our management and affairs and will be able to control most matters requiring shareholder approval, including the election or removal (with or without cause) of directors and the approval of any significant corporate transaction, such as a merger or other sale of us or our assets. In addition, because our Class C capital stock carries no voting rights (except as required by applicable law or as expressly provided in our amended and restated articles of incorporation), the issuance of Class C capital stock (instead of Class A common stock) could prolong the duration of Mr. Barton’s and Mr. Frink’s relative ownership of our voting power. This concentrated control could delay, defer or prevent a change of control, merger, consolidation, takeover, or other business combination involving us that you, as a shareholder, may otherwise support. This concentrated control could also discourage a potential investor from acquiring our Class A common stock or Class C capital stock due to the limited voting power of such stock relative to the Class B common stock and might harm the market price of our Class A common stock and Class C capital stock.

Future Sales of Our Stock in the Public Market Could Cause Our Stock Price to Decline.

Our Class A common stock began trading on The Nasdaq Global Select Market on February 18, 2015, and our Class C capital stock began trading on The Nasdaq Global Select Market on August 17, 2015. We cannot predict the effect, if any, that market sales of shares or the availability of shares for sale will have on the prevailing trading price of our Class A common stock and Class C capital stock from time to time. There is currently no contractual restriction on our ability to issue additional shares, and all of our outstanding shares are generally freely tradable, except for shares held by our “affiliates” as defined in Rule 144 under the Securities Act, which may be sold in compliance with the volume restrictions of Rule 144. Sales of a substantial number of shares of our Class A common stock and Class C capital stock could cause our stock price to decline. In addition, we may in the future issue shares of Class C capital stock for financings, acquisitions or equity incentives. If we issue shares of Class C capital stock in the future, such issuances would have a dilutive effect on the economic interest of our Class A common stock.

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If Securities or Industry Analysts Do Not Publish Research or Publish Inaccurate or Unfavorable Research About Our Business, Our Class A Common Stock and Class C Capital Stock Price and Trading Volume Could Decline.

The trading market for our Class A common stock and Class C capital stock depends in part on the research and reports that securities or industry analysts publish about our company. If few or no securities or industry analysts cover our company, the market price of our publicly-traded stock could be negatively impacted. If securities or industry analysts cover us and if one or more of such analysts downgrade our stock or publish inaccurate or unfavorable research about our business, our stock price would likely decline. If one or more of the analysts covering us fail to publish reports on us regularly, demand for our stock could decline, which could cause our stock price and trading volume to decline.

If We Issue Additional Equity Securities or Issue Convertible Debt to Raise Capital, It May Have a Dilutive Effect on Shareholders’ Investment.

If we raise additional capital through further issuances of equity or convertible debt securities, our existing shareholders could suffer significant dilution in their percentage ownership of us. Moreover, any new equity securities we issue could have rights, preferences and privileges senior to those of holders of our common stock.

Anti-Takeover Provisions in Our Charter Documents and Under Washington Law Could Make an Acquisition of Us More Difficult, Limit Attempts by Shareholders to Replace or Remove Our Management and Affect the Market Price of Our Stock.

Provisions in our articles of incorporation and bylaws, as amended and restated, may have the effect of delaying or preventing a change of control or changes in our management. Our amended and restated articles of incorporation or amended and restated bylaws include provisions, some of which will become effective only after the date, which we refer to as the threshold date, on which the Class B common stock controlled by our founders represents less than 7% of the aggregate number of shares of our outstanding Class A common stock and Class B common stock, that:

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Prior to the threshold date, our directors can be removed with or without cause by holders of our Class A common stock and Class B common stock, voting together as a single group, and vacancies on the board of directors may be filled by such shareholders, voting together as a single group. Given the structure of our capital stock, our founders, Richard Barton and Lloyd Frink, who hold or control our Class B common stock, will have the ability for the foreseeable future to control these shareholder actions. See the risk factor above titled “The Structure of Our Capital Stock as Contained in Our Charter Documents Has the Effect of Concentrating Voting Control With our Founders, and Limits Your Ability to Influence Corporate Matters.”

The provisions described above, after the threshold date, may frustrate or prevent any attempts by our shareholders to replace or remove our current management by making it more difficult for shareholders to replace members of our board of directors, which board is responsible for appointing our management. In addition, because we are incorporated in the State of Washington, we are governed by the provisions of Chapter 23B.19 of the Washington Business Corporation Act, which prohibits certain business combinations between us and certain significant shareholders unless specified conditions are met. These provisions may also have the effect of delaying or preventing a change of control of our company, even if this change of control would benefit our shareholders.

Item 1B. Unresolved Staff Comments

Not applicable.

Item 2. Properties

We have various operating leases for office space and equipment.

Seattle, Washington

In March 2011, we entered into a lease agreement for office space that houses our corporate headquarters in Seattle (as amended from time to time, the “Seattle Lease”). Pursuant to the terms of the Seattle Lease, we currently occupy a total of 155,042 square feet, and we are obligated to make escalating monthly lease payments that began in December 2012 and continue through December 2024. In November 2014, we entered into a lease amendment under which we will lease an additional 113,470 square feet of office space. The Company has taken possession of a portion of the additional office space and will continue to take possession as space becomes available through 2017 under the same terms and conditions.

San Francisco, California

In connection with our February 2015 acquisition of Trulia, Inc. (“Trulia”), we assumed a lease agreement for office space in San Francisco (as amended from time to time, the “San Francisco Lease”), which houses Trulia’s corporate headquarters and beginning in March 2015, also houses Zillow’s personnel located in San Francisco. Pursuant to the terms of the San Francisco Lease, we lease a total of approximately 79,000 square feet, and we are obligated to make escalating monthly lease payments that began in November 2014 and continue through September 2023. In July 2014, Trulia entered into a lease amendment under which we lease an additional 26,620 square feet of office space under the same terms and conditions.

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In November 2012, we entered into an operating lease in San Francisco, California for 18,353 square feet under which we are obligated to make escalating monthly lease payments which began in December 2012 and continue through November 2018. In March 2015, we ceased use of this space in connection with our February 2015 acquisition of Trulia, and in May 2015, we sublet this office space to another occupant. Pursuant to the terms of the operating lease, we lease an additional 8,311 square feet of office space that commenced in October 2015 under the same terms and conditions.

New York, New York

In February 2014, we entered into an operating lease in New York (as amended from time to time, the “New York Lease”). Pursuant to the terms of the New York Lease, we lease a total of approximately 39,900 square feet, and we are obligated to make escalating monthly lease payments that began in August 2014 and continue through November 2024. In July 2015, we sublet approximately 6,650 square feet of this office space to another occupant.

Denver, Colorado

In connection with our February 2015 acquisition of Trulia, we assumed a lease agreement for office space in Denver. Pursuant to the terms of the lease, we lease a total of approximately 65,000 square feet, and we are obligated to make escalating monthly lease payments that began in November 2014 and continue through October 2021.

Irvine, California

In April 2012, we entered into a lease agreement for office space in Irvine (as amended from time to time, the “Irvine Lease”). Pursuant to the terms of the Irvine Lease, we lease a total of approximately 60,000 square feet under which we are obligated to make escalating monthly lease payments which began in August 2012 and continue through July 2022.

We lease additional office space in San Francisco, California, Chicago, Illinois, Denver, Colorado, Cincinnati, Ohio, Lincoln, Nebraska and Vancouver, British Columbia.

Item 3. Legal Proceedings

In March 2010, Smarter Agent, LLC (“Smarter Agent”) filed a complaint against us and multiple other defendants, including HotPads, Inc. (“HotPads”), for patent infringement in the U.S. District Court for the District of Delaware. The complaint alleges, among other things, that our mobile technology infringes three patents held by Smarter Agent purporting to cover: a “Global positioning-based real estate database access device and method,” a “Position-based information access device and method” and a “Position-based information access device and method of searching,” and seeks an injunction against the alleged infringing activities and an unspecified award for damages. In November 2010, the U.S. Patent and Trademark Office granted our petition for re-examination of the three patents-in-suit, and, to date, all claims of all three patents remain rejected in the re-examination proceedings, including through appeals to the Patent Trial and Appeal Board. In March 2011, the court granted a stay of the litigation pending the completion of the re-examination proceedings. In addition, in October 2011, Smarter Agent filed a substantially similar complaint against Diverse Solutions, Inc. (“Diverse Solutions”), StreetEasy, Market Leader (a subsidiary of Trulia), and other defendants, for patent infringement in the U.S. District Court for the District of Delaware. On October 31, 2011, we acquired substantially all of the operating assets and certain liabilities of Diverse Solutions, including the Smarter Agent complaint against Diverse Solutions. On December 14, 2012, we acquired HotPads, and took responsibility for the Smarter Agent complaint against HotPads. On August 26, 2013, we acquired StreetEasy, and took responsibility for the Smarter Agent complaint against StreetEasy. On February 17, 2015, we acquired Trulia, and took responsibility for the Smarter Agent complaint against Market Leader. On September 22, 2015, the court dismissed the case against Zillow, HotPads, and Trulia. On September 25, 2015, the court dismissed the case against Market Leader and Diverse Solutions. On October 6, 2015, the court dismissed the case against StreetEasy.

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In September 2010, LendingTree, LLC (“LendingTree”) filed a complaint against us for patent infringement in the U.S. District Court for the Western District of North Carolina. The complaint alleged, among other things, that our website technology infringes two patents purporting to cover a “Method and computer network for coordinating a loan over the internet.” The complaint sought, among other things, a judgment that we infringed certain patents held by LendingTree, an injunction against the alleged infringing activities and an award for damages. We denied the allegations and asserted defenses and counterclaims seeking declarations that we are not infringing the patents and that the patents are invalid. In March 2014, a federal jury found that Zillow does not infringe the patents and that the patents asserted by LendingTree are invalid. In April, 2014, LendingTree filed two motions for judgment as a matter of law and for a new trial, all of which we opposed. In October 2014, the Court issued an order upholding the jury verdict and denying LendingTree’s motions. In November 2014, LendingTree filed a notice of appeal and, in September 2015, LendingTree filed its opening brief. In December 2015, we filed a response brief to LendingTree’s opening brief.

In March 2014, Move, Inc., the National Association of Realtors and three related entities, filed a complaint against us and Errol Samuelson, our Chief Industry Development Officer, in the Superior Court of the State of Washington in King County, alleging, among other things, that Zillow and Mr. Samuelson misappropriated plaintiffs’ trade secrets in connection with Mr. Samuelson joining Zillow in March 2014. The plaintiffs seek, among other things, an injunction against the alleged misappropriations and Mr. Samuelson working for us, as well as significant monetary damages. In February 2015, plaintiffs filed an amended complaint that, among other things, added Curt Beardsley, our Vice President of MLS Partnerships, as a defendant in the matter. In August 2015, Zillow filed an amended answer and counterclaim against plaintiffs that alleged, among other things, that plaintiffs violated the Washington Trade Secrets Act and aided and abetted a breach of the duty of confidentiality through the public filing of a document that included Zillow’s confidential information and trade secrets. On January 8, 2016, plaintiffs filed a motion seeking sanctions against defendants for alleged evidence spoliation, and defendants each filed a motion for partial summary judgment against plaintiffs regarding the preemption of their common law claims by the Uniform Trade Secrets Act. A hearing was held on February 5, 2016 regarding the motions that the court is currently taking under advisement. An evidentiary hearing regarding plaintiffs’ spoliation motion has been scheduled for April 2016. The plaintiffs recently indicated that they are seeking damages which, if actually awarded, would have a material adverse effect on our business. We believe the plaintiffs’ allegations are without merit and their calculations of damages are baseless. We deny the allegations of any wrongdoing and intend to vigorously defend the claims in the lawsuit. The trial date is scheduled for June 2016.

In August 2014, four purported class action lawsuits were filed by plaintiffs against Trulia and its directors, Zillow, and Zebra Holdco, Inc. in connection with Zillow’s proposed acquisition of Trulia. One of those purported class actions, captioned Collier et al. v. Trulia, Inc., et al., was brought in the Superior Court of the State of California for the County of San Francisco, however on October 7, 2014, plaintiff in the Collier action filed a new complaint in the Delaware Court of Chancery alleging substantially the same claims and seeking substantially the same relief as the original complaint filed in California. On October 8, 2014, plaintiff in the Collier action filed a request for dismissal of the California case without prejudice. The other three of the purported class action lawsuits, captioned Shue et al. v. Trulia, Inc., et al., Sciabacucci et al. v. Trulia, Inc., et al., and Steinberg et al. v. Trulia, Inc. et al., were brought in the Delaware Court of Chancery. All four lawsuits allege that Trulia’s directors breached their fiduciary duties to Trulia stockholders, and that the other defendants aided and abetted such breaches, by seeking to sell Trulia through an allegedly unfair process and for an unfair price and on unfair terms. All lawsuits sought, among other things, equitable relief that would have enjoined the consummation of Zillow’s proposed acquisition of Trulia and attorneys’ fees and costs. The Delaware actions also seek rescission of the Merger Agreement or rescissory damages and orders directing the defendants to account for alleged damages suffered by the plaintiffs and the purported class as a result of the defendants’ alleged wrongdoing. On September 24, 2014, plaintiff in the Sciabacucci action filed (1) a motion for expedited proceedings, (2) a motion for a preliminary injunction, (3) a request for production of documents from defendants, and (4) notice of depositions. On October 13, 2014, the Delaware Court of Chancery issued an order consolidating all of the Delaware actions into one matter captioned In re Trulia, Inc. Stockholder Litigation. On

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October 13 and 14, 2014, the above-referenced motions were refiled under the consolidated case number. On November 14, 2014, plaintiffs again refiled their motion for a preliminary injunction challenging the proposed acquisition. On November 19, 2014, the parties entered into a Memorandum of Understanding, documenting an agreement-in-principle for the settlement of the consolidated litigation, pursuant to which Trulia agreed to make certain supplemental disclosures in a Form 8-K. The Memorandum of Understanding was filed with the Court of Chancery that same day. Thereafter, the parties negotiated and agreed to a stipulation of settlement, and after notice to the class, the Court of Chancery held a settlement hearing on September 16, 2015 where the Court requested the parties to make further submission in connection with the settlement. By an opinion dated January 22, 2016, the Court denied approval of the settlement.

In July 2015, two purported class action lawsuits were filed against us and each of our directors in the Superior Court of the State of Washington in King County, alleging, among other things, that the directors breached their fiduciary duties in connection with the approval of the issuance of non-voting Class C capital stock as a dividend. The complaints seek, among other things, injunctive relief and unspecified monetary damages. A hearing on the plaintiffs’ motion seeking a preliminary injunction to enjoin the issuance of the Class C Stock Split was held on August 5, 2015, and the court denied plaintiffs’ motion for a preliminary injunction. Plaintiffs filed a consolidated class action complaint on September 18, 2015 naming and seeking relief from only our co-founders as defendants. On December 4, 2015, defendants filed a motion to dismiss the consolidated class action complaint, and a hearing to consider that motion to dismiss is scheduled for March 2016.

In March 2015, the Wage and Hour Division of the U.S. Department of Labor (“DOL”) notified the Company that it was initiating a compliance review to determine the Company’s compliance with one or more federal labor laws enforced by the DOL. The Company understands that the scope of this review is limited to the review of the Company’s compliance with certain wage and hour laws with respect to Zillow, Inc. inside sales consultants during a two-year period between 2013 and 2015. In October 2015, the DOL orally informed us that the compliance review is ongoing but that, based on its preliminary findings, it believes the Company may have failed to pay overtime to such inside sales consultants. The DOL has made no assessment of damages or penalties, however, nor has it made a determination that we violated one or more federal labor laws. We have cooperated and continue to cooperate with the DOL in its compliance review. If the DOL were to finally determine that we violated one or more federal labor laws, we may be required to make certain payments of back wages and other amounts to such inside sales consultants or take other corrective actions, and may be subject to fines or penalties.

Although the results of litigation cannot be predicted with certainty, we currently believe we have substantial and meritorious defenses to the outstanding claims.

From time to time, we are involved in litigation and claims that arise in the ordinary course of business and although we cannot be certain of the outcome of any such litigation or claims, nor the amount of damages and exposure that we could incur, we currently believe that the final disposition of such matters will not have a material effect on our business, financial position, results of operations or cash flow. Regardless of the outcome, litigation can have an adverse impact on us because of defense and settlement costs, diversion of management resources and other factors.

Item 4. Mine Safety Disclosures

Not applicable.

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PART II

Item 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

Market Information and Holders

Our Class A common stock has traded on The Nasdaq Global Select Market under the symbol “ZG” since August 17, 2015 and under the symbol “Z” from July 20, 2011 through August 14, 2015. The following table sets forth, for each quarterly period indicated, the high and low sales prices per share for our Class A common stock as quoted on The Nasdaq Global Select Market, adjusted for the Class C Stock Split (see Note 14 of Part II, Item 8 of this Annual Report on Form 10-K for additional information related to the Class C Stock Split):

Our Class B common stock is not listed and there is no established public trading market.

Our Class C capital stock has traded on The Nasdaq Global Select Market under the symbol “Z” since August 17, 2015. Prior to that time, there was no public market for our Class C capital stock. The following table sets forth, for each quarterly period indicated, the high and low sales prices per share for our Class C capital stock as quoted on The Nasdaq Global Select Market:

Holders of Record

As of February 4, 2016, there were 126, three, and 129 holders of record of our Class A common stock, our Class B common stock, and our Class C capital stock, respectively.

Dividends

We have never declared or paid a cash dividend on our common or capital stock and we intend to retain all available funds and any future earnings to fund the development and growth of our business. We therefore do not anticipate paying any cash dividends on our common or capital stock in the foreseeable future. Any future determinations to pay dividends on our common or capital stock would depend on our results of operations, our financial condition and liquidity requirements, restrictions that may be imposed by applicable law or our contracts, and any other factors that our board of directors may consider relevant.

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Recent Sales of Unregistered Securities and Use of Proceeds from Registered Securities

Recent Sales of Unregistered Securities

On February 19, 2015, in connection with a sponsorship agreement involving an equity-based payment to a non-employee recipient, we issued 1,391 (the share amount has not been adjusted for the Class C Stock Split) restricted shares of our Class A common stock to the recipient. This transaction was exempt from registration under the Securities Act in reliance upon Section 4(a)(2) of the Securities Act and Regulation D promulgated thereunder. The recipient of restricted shares of our Class A common stock in this transaction represented their intentions to acquire the securities for investment only and not with a view to or for sale in connection with any distribution thereof, and appropriate legends were placed upon the stock certificates issued in these transactions. The recipient had adequate access, through their relationships with us, to information about Zillow Group.

There were no other sales of unregistered securities during the year ended December 31, 2015.

Purchases of Equity Securities by the Issuer

None.

Performance Graph

The following graph compares our cumulative total shareholder return on Zillow Group’s common stock with the NASDAQ Composite Index and the RDG Internet Composite Index.

For our Class A common stock, this graph covers the period from July 20, 2011, using the closing price for the first day of trading immediately following the effectiveness of our initial public offering per SEC regulations, through December 31, 2015 (adjusted to give effect to the Class C Stock Split). This graph assumes that the value of the investment in Zillow Group’s Class A common stock and each index (including reinvestment of dividends) was $100 on July 20, 2011.

For our Class C capital stock, this graph covers the period from August 3, 2015, using the closing price for the first day of trading during the when-issued trading period prior to the Class C Stock Split, through December 31, 2015. This graph assumes that the value of the investment in Zillow Group’s Class C capital stock (including reinvestment of dividends) was $100 on August 3, 2015.

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The information contained in the graph is based on historical data and is not intended to forecast possible future performance.

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Item 6. Selected Financial Data

The selected financial data set forth below should be read in conjunction with the information under “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our consolidated financial statements and related notes included elsewhere in this Annual Report on Form 10-K and our previously audited financial statements that are not included herein. We have included Trulia, Inc. in Zillow Group’s results of operations prospectively after February 17, 2015, the date of acquisition. Our historical results are not necessarily indicative of our results to be expected in any future period. We have given retroactive effect to prior period share and per share amounts in our consolidated statements of operations for the August 2015 Class C Stock Split so that prior periods are comparable to current period presentation (see Note 14 of Part II, Item 8 of this Annual Report on Form 10-K for additional information related to the Class C Stock Split).

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Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion of our financial condition and results of operations should be read in conjunction with our audited consolidated financial statements and the related notes included elsewhere in this Annual Report on Form 10-K. In addition to historical financial information, the following discussion contains forward-looking statements that reflect our plans, estimates and beliefs. Our actual results may differ materially from those contained in or implied by any forward-looking statements. Factors that could cause or contribute to these differences include those discussed below and elsewhere in this Annual Report on Form 10-K, particularly in “Risk Factors”.

Overview of our Business

Zillow Group, Inc. operates the leading real estate and home-related information marketplaces on mobile and the Web, with a complementary portfolio of brands and products to help people find vital information about homes and connect with local professionals. Zillow Group’s brands focus on all stages of the home lifecycle: renting, buying, selling, financing and home improvement. The Zillow Group portfolio of consumer brands includes real estate and rental marketplaces Zillow, Trulia, StreetEasy and HotPads. In addition, Zillow Group works with tens of thousands of real estate agents, mortgage and rental professionals, helping maximize business opportunities and connect to millions of consumers. We also own and operate a number of brands for real estate, rental and mortgage professionals, including DotLoop, Mortech, Diverse Solutions and Retsly.

We generate revenue from the sale of advertising services and our suite of tools to businesses and professionals primarily associated with the real estate, rental and mortgage industries. These professionals include local real estate and rental professionals, mortgage professionals and brand advertisers. Our two revenue categories are marketplace revenue and display revenue.

Marketplace revenue for the year ended December 31, 2015 consisted of real estate, mortgages, and Market Leader revenue. Real estate revenue primarily includes revenue from the sale of advertising services and a suite of tools sold to real estate professionals, as well as revenue generated by Zillow Group Rentals, which includes our rentals marketplace and suite of tools for rental professionals. Mortgages revenue primarily includes advertising sold to mortgage lenders and other mortgage professionals, as well as revenue generated by Mortech, which provides subscription-based mortgage software solutions, including a product and pricing engine and lead management platform. Market Leader revenue primarily includes revenue from the sale of a comprehensive premium software-as-a-service based marketing product typically sold to real estate professionals as a bundle of products under a fixed fee subscription. Market Leader revenue is included in our results of operations from February 17, 2015 through the date of divestiture of September 30, 2015.

Display revenue primarily consists of graphical mobile and web advertising sold on a cost per thousand impressions (“CPM”) or cost-per-click (“CPC”) basis to advertisers promoting their brands on our mobile applications and websites and our partner websites. Impressions are delivered when a sold advertisement appears on pages viewed by users of our mobile applications and websites.

Overview of Significant Milestones and Results

The following is a summary of our significant milestones for the year ended December 31, 2015:

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We have included Trulia in Zillow Group’s results of operations prospectively after February 17, 2015, the date of acquisition. Because the Trulia acquisition occurred during the year ended December 31, 2015, the information presented in this section with respect to the year ended December 31, 2015 relates to Zillow Group, and the information presented in this section with respect to the prior-year comparable periods relates to Zillow on a standalone basis. As a result, comparisons to the prior-year period may not be indicative of future results or future rates of growth.

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We have experienced significant revenue growth over the past three years. In 2013, 2014 and 2015 we focused on growing our marketplace revenue, which accounted for the majority of our revenue growth over that period. The increase in marketplace revenue resulted primarily from growth in our Premier Agent program. Our Premier Agent program represents the primary source of our revenue and is more predictable than our other revenue sources. As a greater proportion of our revenue has shifted to marketplace revenue with a corresponding lesser proportion of revenue being display revenue, we believe we are experiencing less quarterly seasonality in our business as compared to prior periods.

For the years ended December 31, 2015, 2014, and 2013, we generated revenue of $644.7 million, $325.9 million and $197.5 million, respectively, representing year-over-year growth of 98%, 65% and 69%, respectively. We believe achieving these levels of revenue growth was primarily the result of significant growth in the following areas:

As of December 31, 2015, we had 2,204 full-time employees compared to 1,215 full-time employees as of December 31, 2014. The increase in the number of full-time employees was primarily due to the inclusion of Trulia after February 17, 2015.

Acquisition of Trulia, Inc.

Effective February 17, 2015, pursuant to the Agreement and Plan of Merger dated as of July 28, 2014 (the “Merger Agreement”), each of Zillow and Trulia became wholly owned subsidiaries of Zillow Group. Upon completion of the acquisition, each outstanding share of Class A common stock of Zillow was converted into the right to receive one share of fully paid and nonassessable Class A common stock of Zillow Group, each outstanding share of Class B common stock of Zillow was converted into the right to receive one share of fully paid and nonassessable Class B common stock of Zillow Group, and each outstanding share of Trulia common stock was converted into the right to receive 0.444 of a share of fully paid and nonassessable Class A Common Stock of Zillow Group.

The total purchase price of Trulia was approximately $2.0 billion. For additional information regarding the transaction with Trulia, see Note 7 to our consolidated financial statements.

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On February 17, 2015, in connection with the Trulia acquisition, Zillow Group undertook a restructuring plan that resulted in a total workforce reduction of nearly 350 employees, primarily to eliminate overlapping positions in the sales and marketing functions related to Trulia’s workforce at its Bellevue, Denver, New York and San Francisco locations. The restructuring plan is a result of the integration of Trulia’s business and operations with and into Zillow Group’s business. Employees directly affected by the restructuring plan were provided with severance payments, stock vesting acceleration and outplacement assistance. For additional information regarding the restructuring, see Note 18 to our consolidated financial statements.

Key Growth Drivers

To analyze our business performance, determine financial forecasts and help develop long-term strategic plans, we frequently review the following key growth drivers:

Unique Users

Measuring unique users is important to us because our marketplace revenue depends in part on our ability to enable real estate, rental and mortgage professionals to connect with our users, and our display revenue depends in part on the number of impressions delivered. Furthermore, our community of users improves the quality of our living database of homes with their contributions. We count a unique user the first time an individual accesses one of our mobile applications using a mobile device during a calendar month and the first time an individual accesses one of our websites using a web browser during a calendar month. If an individual accesses our mobile applications using different mobile devices within a given month, the first instance of access by each such mobile device is counted as a separate unique user. If an individual accesses more than one of our mobile applications within a given month, the first access to each mobile application is counted as a separate unique user. If an individual accesses our websites using different web browsers within a given month, the first access by each such web browser is counted as a separate unique user. If an individual accesses more than one of our websites in a single month, the first access to each website is counted as a separate unique user since unique users are tracked separately for each domain. Zillow measures unique users with Google Analytics and Trulia measures unique users with Omniture analytical tools. Beginning on February 17, 2015, the reported monthly unique users reflect the effect of Zillow Group’s February 17, 2015 acquisition of Trulia. Beginning in September 2013, the reported monthly unique users reflect the effect of Zillow’s August 26, 2013 acquisition of StreetEasy, Inc.

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Agent Advertisers

The number of Agent Advertisers is an important driver of revenue growth because each advertiser pays us a fee to purchase advertising services. We define an Agent Advertiser as a real estate professional with an active advertising contract at the end of a period. Beginning on February 17, 2015, the reported Agent Advertisers reflect the effect of Zillow Group’s February 17, 2015 acquisition of Trulia. The number of Agent Advertisers excludes users of our Market Leader products who do not also have an active advertising contract for our Premier Agent advertising products.

Basis of Presentation

Revenue

We generate revenue from the sale of advertising services and our suite of tools to businesses and professionals primarily associated with the real estate and mortgage industries. These professionals include local real estate and rental professionals, mortgage professionals and brand advertisers. Our two revenue categories are marketplace revenue and display revenue.

Marketplace Revenue. Marketplace revenue for the year ended December 31, 2015 consisted of real estate, mortgages, and Market Leader revenue.

Real estate revenue primarily includes revenue from advertising and a suite of tools sold to real estate professionals, as well as revenue generated by Zillow Group Rentals, which includes our rentals marketplace and suite of tools for rental professionals.

In August 2015, Zillow Group completed the integration of certain Zillow and Trulia agent advertising products, effectively eliminating the Trulia Local Ads and Trulia Mobile Ads products. As a result of the integration, Agent Advertisers can manage their advertising across both Zillow and Trulia mobile and Web through the combined Premier Agent platform.

Our Zillow Premier Agent program, which is included in real estate revenue, offers a suite of marketing and business technology solutions to help real estate agents grow their businesses and personal brands. The Premier Agent program allows agents to select products and services that they can tailor to meet their business and advertising needs. The program has three tiers of participation including Premier Platinum, our flagship product, as well as Premier Gold and Premier Silver, to meet different marketing and business needs of a broad range of agents. All tiers of Premier Agents receive access to a dashboard portal on our website that provides individualized program performance analytics, as well as our personalized website service, and our free customer relationship management, or CRM, tool that captures detailed information about each contact made with a Premier Agent through our mobile and web platforms. Our Premier Gold product also includes featured listings whereby the agent’s listings will appear at the top of search results on our mobile and web platforms. Our Premier Platinum product includes the dashboard portal on our website, our personalized website service, our CRM tool, featured listings, and inclusion on our buyer’s agent list, whereby the agent appears as the agent to contact for listings in the purchased zip code. We charge for our Platinum Premier Agent product based on the number of impressions delivered on our buyer’s agent list in zip codes purchased and a contracted maximum cost per impression. Our Platinum Premier Agent product includes multiple deliverables which are accounted for as a single unit of accounting, as the delivery or performance of the undelivered elements is based on traffic to our mobile applications and websites. We recognize revenue related to our impression-based Platinum Premier Agent product based on the lesser of (i) the actual number of impressions delivered on our buyer’s agent list during the period multiplied by the contracted maximum cost per impression, or (ii) the contractual maximum spend on a

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straight-line basis during the contractual period over which the services are delivered, typically over a period of six months or twelve months and then month-to-month thereafter. We charge a fixed subscription fee for Zillow’s Premier Gold and Premier Silver subscription products. Subscription advertising revenue for our Premier Gold and Premier Silver subscription products is recognized on a straight-line basis during the contractual period over which the services are delivered, typically over a period of six months and then month-to-month thereafter.

Our Trulia real estate products included in real estate revenue are primarily sold on a fixed fee subscription basis, and include Trulia Local Ads, Trulia Mobile Ads, Trulia Pro with featured listings and Trulia Seller Ads. Prior to the August 2015 integration of certain of Zillow’s and Trulia’s advertising products, Trulia Local Ads and Trulia Mobile Ads enabled real estate professionals to promote themselves on Trulia’s search results pages and property details pages for a local market area. Real estate professionals purchased subscriptions to these products based upon their specified market share for a city or zip code, at a fixed monthly price, for periods ranging from one month to one year, with pricing depending on demand, location, and the percentage of market share purchased. Following the August 2015 agent advertising product integration, Trulia Local Ads and Trulia Mobile Ads products are no longer sold by Zillow Group. Trulia’s featured listings product allows real estate professionals to receive prominent placement of their listings in Trulia’s search results. Real estate professionals sign up for new subscriptions to this product at a fixed monthly price for periods that generally range from six months to 12 months. Trulia Seller Ads enable real estate professionals to generate leads from consumers interested in selling their homes. Subscription advertising revenue for Trulia’s real estate products included in real estate revenue is recognized on a straight-line basis during the contractual period over which the services are delivered.

Rentals revenue, which is included in real estate revenue, primarily includes advertising sold to property managers and other rental professionals on a cost per lead and cost per lease generated basis. We recognize revenue as leads are delivered to rental professionals or as qualified leases are confirmed.

Mortgages revenue primarily includes advertising sold to mortgage lenders and other mortgage professionals on a cost per lead basis, as well as revenue generated by Mortech, which provides subscription-based mortgage software solutions, including a product and pricing engine and lead management platform, for which we recognize revenue on a straight-line basis during the contractual period over which the services are delivered. For our cost per lead mortgage advertising products, participating qualified mortgage professionals make a prepayment to gain access to consumers interested in connecting with mortgage professionals. Consumers who request rates for mortgage loans are presented with personalized quotes from participating mortgage professionals. We only charge mortgage professionals a fee when users contact mortgage professionals for more information regarding a mortgage loan quote. Mortgage professionals who exhaust their initial prepayment can then prepay additional funds to continue to participate in the marketplace. We recognize revenue when a user contacts a mortgage professional through Zillow Group’s mortgages platform.

Market Leader revenue primarily includes revenue from the sale of a comprehensive premium software-as-a-service based marketing product typically sold to real estate professionals as a bundle of products under a fixed fee subscription. Market Leader became part of Zillow Group through Zillow Group’s February 2015 acquisition of Trulia.

Display Revenue. Display revenue primarily consists of graphical mobile and web advertising sold on a cost per thousand impressions (“CPM”) or cost-per-click (“CPC”) basis to advertisers promoting their brands on our mobile applications and websites and our partner websites, primarily in the real estate industry, including real estate brokerages, home builders, mortgage professionals and home services providers. Our advertising customers also include telecommunications, automotive, insurance and consumer products companies. Impressions are the number of times an advertisement is loaded on a web page and clicks are the number of times users click on an advertisement. Pricing is primarily based on advertisement size and position on our mobile applications and websites, and fees are generally billed monthly. We recognize display revenue as clicks occur or

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as impressions are delivered to users interacting with our mobile applications or websites. Growth in display revenue depends on continuing growth in traffic to our mobile applications and websites and migration of advertising spend online from traditional broadcast and print media.

Costs and Expenses

Cost of Revenue. Our cost of revenue consists of expenses related to operating our mobile applications and websites, including associated headcount expenses, such as salaries and benefits and share-based compensation expense and bonuses, as well as credit card fees, ad serving costs paid to third parties, revenue-sharing costs related to our commercial business relationships, costs to generate leads for customers, multiple listing services fees and costs associated with the operation of our data center and customer websites.

Sales and Marketing. Sales and marketing expenses consist of advertising costs and other sales expenses related to promotional and marketing activities, as well as headcount expenses, including salaries, commissions, benefits, share-based compensation expense and bonuses for sales, sales support, customer support, marketing and public relations employees.

Technology and Development. Technology and development expenses consist of headcount expenses, including salaries and benefits, share-based compensation expense and bonuses for salaried employees and contractors engaged in the design, development and testing of our mobile applications and websites, equipment and maintenance costs, and facilities costs allocated on a headcount basis. Technology and development expenses also include amortization costs related to capitalized website and development activities, amortization of certain intangibles and other data agreement costs related to the purchase of data used to populate our mobile applications and websites, and amortization of intangible assets recorded in connection with acquisitions.

General and Administrative. General and administrative expenses consist of headcount expenses, including salaries, benefits, share-based compensation expense and bonuses for executive, finance, accounting, legal, human resources, recruiting and administrative support. General and administrative expenses also include legal, accounting and other third-party professional service fees and bad debt expense.

Acquisition-related Costs. Acquisition-related costs consist of investment banker, legal, accounting, tax, and regulatory filing fees associated with acquisitions.

Restructuring Costs. Restructuring costs consist of workforce reduction expenses in connection with a restructuring plan and related contract termination costs related to operating leases.

Loss on Divestiture of Business. Loss on divestiture of business consists of the loss recognized in connection with our September 2015 sale of the Market Leader business.

Other Income

Other income consists primarily of interest income earned on our cash, cash equivalents and investments.

Interest Expense

Interest expense consists of interest on the 2020 Notes we guaranteed in connection with our February 2015 acquisition of Trulia. Interest is payable on the 2020 Notes at the rate of 2.75% semi-annually on June 15 and December 15 of each year.

Income Taxes

We are subject to federal and state income taxes in the United States and in Canada. During the years ended December 31, 2015, 2014 and 2013, we did not have a material amount of reportable taxable income. We have provided a full valuation allowance against our net deferred tax assets as of December 31, 2015 and 2014

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because, based on the weight of available evidence, it is more likely than not (a likelihood of more than 50%) that some or all of the deferred tax assets will not be realized. Therefore, no related tax liability or expense has been recorded in the financial statements. We have accumulated federal tax losses of approximately $735.2 million as of December 31, 2015, which are available to reduce future taxable income. We have accumulated state tax losses of approximately $11.6 million (tax effected) as of December 31, 2015.

We recorded an income tax benefit of $4.6 million for the year ended December 31, 2015, primarily due to a deferred tax liability generated in connection with Zillow’s August 20, 2015 acquisition of DotLoop that can be used to realize certain deferred tax assets for which we had previously provided a full allowance. We recorded an income tax benefit of $4.1 million for the year ended December 31, 2013 due to a deferred tax liability generated in connection with Zillow’s August 26, 2013 acquisition of StreetEasy, Inc. that can be used to realize certain deferred tax assets for which we had previously provided a full allowance.

Results of Operations

The following tables present our results of operations for the periods indicated and as a percentage of total revenue:

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Adjusted EBITDA

To provide investors with additional information regarding our financial results, we have disclosed Adjusted EBITDA within this Annual Report on Form 10-K, a non-GAAP financial measure. We have provided a reconciliation below of Adjusted EBITDA to net loss, the most directly comparable GAAP financial measure.

We have included Adjusted EBITDA in this Annual Report on Form 10-K as it is a key metric used by our management and board of directors to measure operating performance and trends and to prepare and approve our annual budget. In particular, the exclusion of certain expenses in calculating Adjusted EBITDA facilitates operating performance comparisons on a period-to-period basis.

Our use of Adjusted EBITDA has limitations as an analytical tool, and you should not consider it in isolation or as a substitute for analysis of our results as reported under GAAP. Some of these limitations are:

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Because of these limitations, you should consider Adjusted EBITDA alongside other financial performance measures, including various cash flow metrics, net loss and our other GAAP results.

The following table presents a reconciliation of Adjusted EBITDA to net loss for each of the periods presented:

Year Ended December 31, 2015 Compared to Year Ended December 31, 2014

Revenue

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Overall revenue increased by $318.8 million, or 98%, for the year ended December 31, 2015 compared to the year ended December 31, 2014. Marketplace revenue increased by 108%, and display revenue increased by 51%.

Marketplace revenue grew to $555.9 million for the year ended December 31, 2015 from $267.2 million for the year ended December 31, 2014, an increase of $288.7 million. Marketplace revenue represented 86% of total revenue for the year ended December 31, 2015 compared to 82% of total revenue for the year ended December 31, 2014. The increase in marketplace revenue was primarily attributable to the $243.1 million increase in real estate revenue, which, in turn, was primarily attributable to our February 2015 acquisition of Trulia. The inclusion of Trulia Agent Advertisers contributed to growth in the number of Agent Advertisers to 92,366 as of December 31, 2015 from 62,305 as of December 31, 2014, representing growth of 48%. Real estate revenue was also positively impacted by a strategic shift to focus efforts by our sales team on high-performing Agent Advertisers. This strategic shift resulted in increased sales to Agent Advertisers looking to expand their presence on our platform. Average monthly revenue per advertiser increased by 43% to $482 for the year ended December 31, 2015 from $338 for the year ended December 31, 2014. We calculate our average monthly revenue per advertiser by dividing the revenue generated by Zillow’s Premier Agent program and Trulia’s real estate revenue products (excluding revenue generated by Market Leader) in the period by the average number of Agent Advertisers in the period, divided again by the number of months in the period. If a real estate professional had an active advertising contract for both our Zillow Premier Agent and Trulia agent advertising products, the professional is counted as one Agent Advertiser. The average number of Agent Advertisers is derived by calculating the average of the beginning and ending number of Agent Advertisers for the period. The increase in average monthly revenue per advertiser was primarily driven by an increase in impression inventory, which led to an increase in sales to existing Agent Advertisers looking to expand their presence on our platform, and was also due to our February 2015 acquisition of Trulia.

The increase in marketplace revenue was also attributable to growth in mortgages revenue, which increased by $16.1 million, or 57%, for the year ended December 31, 2015 compared to the year ended December 31, 2014. The increase in mortgages revenue was primarily a result of an increase in the number of loan information requests submitted by consumers, which reflects the inclusion of loan information requests submitted by consumers through Trulia after February 17, 2015. There were approximately 46.8 million mortgage loan information requests submitted by consumers for the year ended December 31, 2015 compared to 25.7 million mortgage loan information requests submitted by consumers for the year ended December 31, 2014, an increase of 82%. The growth in loan information requests submitted by consumers increases the likelihood that consumers’ contact information will be converted into leads, but there is not a direct correlation between the number of loan information requests and mortgages revenue because loan information requests do not always result in revenue recognition. During the first half of 2015 we changed the pricing model for our mortgage advertising products from cost-per-click to cost-per-lead, which also may have contributed to growth in mortgages revenue.

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The increase in marketplace revenue was also attributable to the addition of Market Leader revenue following our February 2015 acquisition of Trulia. Market Leader revenue was $29.5 million for the year ended December 31, 2015. Market Leader revenue is included in our results of operations from February 17, 2015 through the date of its divestiture on September 30, 2015.

Display revenue was $88.8 million for the year ended December 31, 2015 compared to $58.7 million for the year ended December 31, 2014, an increase of $30.1 million. Display revenue represented 14% of total revenue for the year ended December 31, 2015 compared to 18% of total revenue for the year ended December 31, 2014. The increase in display revenue was primarily the result of an increase in the number of unique users to our mobile applications and websites, which increased to 123.7 million average monthly unique users for the three months ended December 31, 2015 from 76.7 million average monthly unique users for the three months ended December 31, 2014, representing growth of 61%. The growth in unique users was primarily due to our February 2015 acquisition of Trulia, which increased the number of graphical display impressions available for sale and advertiser demand for graphical display inventory. Although there is a relationship between the number of average monthly unique users and display revenue, there is not a direct correlation, as we do not sell our entire display inventory each period and some of our inventory is sold through networks and not directly through our sales team, which impacts the cost per impression we charge to customers.

Cost of Revenue

Cost of revenue was $61.6 million for the year ended December 31, 2015 compared to $29.5 million for the year ended December 31, 2014, an increase of $32.2 million, or 109%. The increase in cost of revenue was primarily attributable to increased headcount-related expenses of $9.2 million, including share-based compensation expense, driven by growth in headcount, including the impact of growth in headcount as a result of our February 2015 acquisition of Trulia, increased credit card and ad serving fees of $8.5 million, an $8.0 million increase in data center and connectivity costs, a $3.1 million increase in costs to generate leads for customers related to the Market Leader business, a $1.1 million increase in print expenses related to the Market Leader business, a $0.6 million increase in multiple listing service fees, a $0.4 million increase in revenue share costs, and a $1.3 million increase in miscellaneous cost of revenue expenses. We expect our cost of revenue to increase in absolute dollars in future years as we continue to incur more expenses that are associated with growth in revenue.

Sales and Marketing

Sales and marketing expenses were $307.1 million for year ended December 31, 2015 compared to $169.5 million for the year ended December 31, 2014, an increase of $137.6 million, or 81%. The increase in sales and marketing expenses was primarily attributable to increased headcount-related expenses of $88.6 million, including share-based compensation expense, including the impact of growth in headcount as a result of our February 2015 acquisition of Trulia, which resulted in significant growth in the size of our sales team.

In addition to the increases in headcount-related expenses, marketing and advertising expenses increased by $33.3 million, primarily related to advertising spend to acquire shoppers across online and offline channels, which supports our growth initiatives.

We also incurred a $4.8 million increase in software and connectivity costs, a $4.7 million increase in tradeshow and conferences expense, including related travel costs, a $4.2 million increase in consulting costs, a $1.2 million increase in depreciation expense, and a $0.8 million increase in miscellaneous sales and marketing expenses.

We expect our sales and marketing expenses to increase in absolute dollars in future years as we continue to expand our sales team and invest more resources in extending our audience through marketing and advertising initiatives.

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Technology and Development

Technology and development expenses, which include research and development costs, were $198.6 million for the year ended December 31, 2015 compared to $84.7 million for the year ended December 31, 2014, an increase of $113.9 million, or 135%. Approximately $50.0 million of the increase related to growth in headcount-related expenses, including share-based compensation expense, including the impact of growth in headcount as a result of our February 2015 acquisition of Trulia, as we continue to grow our engineering headcount to support current and future product initiatives. Approximately $27.3 million of the increase was the result of increased amortization of acquired intangible assets, primarily as a result of our February 2015 acquisition of Trulia. The increase in technology and development expenses was also attributable to a $15.5 million increase in other non-capitalizable data content expense, a $6.4 million increase in amortization related to website development costs and purchased content, a $4.5 million increase in depreciation expense, a $4.3 million increase in consulting costs, a $3.2 million increase in software, hardware and connectivity costs, a $0.9 million increase in repairs and maintenance expense, a $0.8 million increase in travel and meals expense, a $0.7 million increase in dues and subscriptions, and a $0.3 million increase in various miscellaneous expenses.

Amortization expense included in technology and development related to intangible assets recorded in connection with acquisitions was $33.4 million and $6.1 million, respectively, for the year ended December 31, 2015 and 2014. Amortization expense included in technology and development for capitalized website development costs was $23.9 million and $18.3 million, respectively, for the year ended December 31, 2015 and 2014. Other data content expense was $16.2 million and $0.7 million, respectively, for the year ended December 31, 2015 and 2014. Amortization expense included in technology and development for purchased data content intangible assets was $5.9 million and $5.1 million, respectively, for the year ended December 31, 2015 and 2014. We expect our technology and development expenses to increase in absolute dollars over time as we continue to build new mobile and website functionality.

General and Administrative

General and administrative expenses were $170.4 million for the year ended December 31, 2015 compared to $65.5 million for the year ended December 31, 2014, an increase of $104.9 million, or 160%. The increase in general and administrative expenses was primarily a result of a $49.2 million increase in headcount-related expenses, including share-based compensation expense, driven primarily by growth in headcount in shared corporate services to support our engineering and other teams, including the impact of growth in headcount as a result of our February 2015 acquisition of Trulia, and increases in compensation, and a $35.4 million increase in professional services fees, including legal fees incurred in connection with the legal proceedings described in Part I, Item 3. For the year ended December 31, 2015, we incurred $27.1 million in legal costs related to our litigation with Move, Inc.

In addition to the increases in headcount-related expenses and professional services fees, general and administrative expenses increased as a result of a $10.6 million increase in building lease-related expenses including rent, utilities and insurance, a $3.0 million increase in consulting costs, a $2.9 million increase in travel and meals expense, a $2.0 million increase in software, hardware, and connectivity costs, a $0.7 million increase in bad debt expense, a $0.5 million increase in city and state taxes and a $0.6 million increase in various other miscellaneous expenses.

We expect general and administrative expenses to increase over time in absolute dollars as we continue to expand our business.

Acquisition-Related Costs

Acquisition-related costs were $16.6 million for the year ended December 31, 2015 as a result of our February 2015 acquisition of Trulia and our August 2015 acquisition of DotLoop, including legal, accounting

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and tax fees. Acquisition-related costs were $21.5 million for the year ended December 31, 2014 as a result of our acquisition of Trulia. We expect our acquisition-related costs to decrease in future periods as we focus on the integration of Trulia and DotLoop.

Restructuring Costs

Restructuring costs were $35.6 million for the year ended December 31, 2015. On February 17, 2015, in connection with the February 2015 acquisition of Trulia, Zillow Group undertook a restructuring plan that resulted in a total workforce reduction of nearly 350 employees, primarily to eliminate overlapping positions in the sales and marketing functions related to Trulia’s workforce at its Bellevue, Denver, New York and San Francisco locations. The restructuring plan is a result of the integration of Trulia’s business and operations with and into Zillow Group’s business. Employees directly affected by the restructuring plan were provided with severance payments, stock vesting acceleration and outplacement assistance. As of December 31, 2015, the restructuring plan is substantially complete.

Primarily as a result of the restructuring plan, Zillow Group recorded a restructuring charge of approximately $35.6 million during the year ended December 31, 2015, including approximately $12.2 million for severance and other personnel related expenses, approximately $14.9 million of non-cash expenses relating to stock vesting acceleration or a reduced remaining requisite service period, and approximately $8.2 million for contract termination costs associated with certain operating leases. Zillow Group recognized certain contract termination costs primarily associated with Trulia’s Bellevue operating lease, as well as Zillow’s San Francisco operating lease, as Zillow’s employees in San Francisco were relocated into Trulia’s San Francisco office space. The restructuring costs for contract termination costs include approximately $4.0 million primarily related to the write-off of certain leasehold improvements. For additional information regarding the restructuring, see Note 18 to our consolidated financial statements.

Loss on Divestiture of Business

The loss on divestiture of business was $4.4 million for the year ended December 31, 2015 and relates to the September 2015 sale of our Market Leader business. For additional information regarding the divestiture of Market Leader, see Note 8 to our consolidated financial statements.

Interest Expense

Interest expense was $5.5 million for the year ended December 31, 2015. The interest expense relates to the 2020 Notes that we guaranteed in connection with the February 2015 acquisition of Trulia, which accrue interest at 2.75% annually. For additional information regarding the 2020 Notes, see Note 12 to our condensed consolidated financial statements.

Income Taxes

During the years ended December 31, 2015 and 2014, we did not have a material amount of reportable taxable income. Therefore, no tax liability or expense has been recorded in the consolidated financial statements for the years ended December 31, 2015 and 2014.

We recorded an income tax benefit of approximately $4.6 million for the year ended December 31, 2015 primarily due to the deferred tax liability generated in connection with Zillow’s August 20, 2015 acquisition of DotLoop that can be used to realize certain deferred tax assets for which we had previously provided a full valuation allowance.

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Year Ended December 31, 2014 Compared to Year Ended December 31, 2013

Revenue

Overall revenue increased by $128.3 million, or 65%, for the year ended December 31, 2014 compared to the year ended December 31, 2013. Marketplace revenue increased by 73%, and display revenue increased by 37%.

Marketplace revenue grew to $267.2 million for the year ended December 31, 2014 from $154.7 million for the year ended December 31, 2013, an increase of $112.5 million. Marketplace revenue represented 82% of total revenue for the year ended December 31, 2014 compared to 78% of total revenue for the year ended December 31, 2013. The increase in marketplace revenue was primarily attributable to the $106.1 million increase in real estate revenue, which was primarily a result of growth in sales to existing Agent Advertisers looking to expand their presence on our platform, which growth was supported by increased impression inventory, as well as growth in the number of advertisers in our Premier Agent program to 62,305 as of December 31, 2014 from 48,314 as of December 31, 2013, representing growth of 29%. Average monthly revenue per advertiser increased by 27% to $338 for the year ended December 31, 2014 from $267 for the year ended December 31, 2013. The increase in average monthly revenue per advertiser was primarily driven by an increase in impression inventory, which led to an increase in sales to existing Premier Agent advertisers looking to expand their presence on our platform.

The increase in marketplace revenue was also attributable to growth in mortgages revenue, which increased by $6.4 million, or 29%, for the year ended December 31, 2014 compared to the year ended December 31, 2013. The increase in mortgages revenue was primarily a result of an increase in the number of loan information requests submitted by consumers. There were approximately 25.7 million mortgage loan information requests submitted by consumers for the year ended December 31, 2014 compared to 20.2 million mortgage loan information requests submitted by consumers for the year ended December 31, 2013, an increase of 27%.

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Display revenue was $58.7 million for the year ended December 31, 2014 compared to $42.8 million for the year ended December 31, 2013, an increase of $15.8 million. Display revenue represented 18% of total revenue for the year ended December 31, 2014 compared to 22% of total revenue for the year ended December 31, 2013. The increase in display revenue was primarily the result of an increase in the number of unique users to our mobile applications and websites, which increased to 76.7 million average monthly unique users for the three months ended December 31, 2014 from 54.4 million average monthly unique users for the three months ended December 31, 2013, representing growth of 41%. The growth in unique users increased the number of graphical display impressions available for sale and advertiser demand for graphical display inventory. Although there is a relationship between the number of average monthly unique users and display revenue, there is not a direct correlation, as the Company does not sell its entire display inventory each period and some of the inventory is sold through networks and not directly through our sales team, which impacts the cost per impression we charge to display advertising customers. As a result, the growth rate in the Company’s average monthly unique users outpaced the growth rate of display revenue.

Cost of Revenue

Cost of revenue was $29.5 million for the year ended December 31, 2014 compared to $18.8 million for the year ended December 31, 2013, an increase of $10.7 million, or 57%. The increase in cost of revenue was attributable to increased headcount-related expenses of $3.4 million, including share-based compensation expense, driven by growth in headcount, increased credit card and ad serving fees of $3.1 million, a $2.1 million increase in data center and connectivity costs, a $1.3 million increase in revenue share costs, and a $0.8 million increase in various miscellaneous expenses, including royalties.

Sales and Marketing

Sales and marketing expenses were $169.5 million for the year ended December 31, 2014 compared to $108.9 million for the year ended December 31, 2013, an increase of $60.6 million, or 56%. The increase in sales and marketing expenses was primarily due to a $34.7 million increase in marketing and advertising expenses, primarily related to advertising spend to acquire shoppers across online and offline channels, which supports our growth initiatives, and a $3.0 million increase in consulting costs to support our marketing and advertising spend. We believe we have considerable opportunity to increase brand awareness and grow traffic through targeted advertising programs. As such, we plan to continue to selectively advertise to consumers and professionals in various online and offline channels that have tested well for us to drive traffic and brand awareness for Zillow.

In addition to the increases in marketing and advertising expenses, headcount-related expenses, including share-based compensation expense, increased by $16.9 million, driven primarily by growth in the size of our sales team. We also incurred a $2.5 million increase in software and connectivity costs, a $2.4 million increase in tradeshow and conferences expense, including related travel costs, and a $1.1 million increase in depreciation expense.

Technology and Development

Technology and development expenses, which include research and development costs, were $84.7 million for the year ended December 31, 2014 compared to $48.5 million for the year ended December 31, 2013, an increase of $36.2 million, or 75%. Approximately $18.3 million of the increase related to growth in headcount-related expenses, including share-based compensation expense, as we continue to grow our engineering headcount to support current and future product initiatives. Approximately $9.7 million of the increase was the result of increased amortization of intangible assets, including website development costs, purchased content and acquired intangible assets. Approximately $3.3 million of the increase related to the impairment of certain acquired intangible assets during the year ended December 31, 2014, primarily related to intangible assets obtained in connection with our 2012 acquisition of RentJuice Corporation. The increase in technology and

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development expenses was also attributable to a $1.9 million increase in depreciation expense, a $1.3 million increase in consulting costs, a $0.6 million increase in software and hardware costs, a $0.4 million increase in the loss on disposal of property and equipment, and a $0.7 million increase in various miscellaneous expenses.

Amortization expense included in technology and development for capitalized website development costs was $18.3 million and $12.2 million, respectively, for the years ended December 31, 2014 and 2013. Amortization expense included in technology and development related to intangible assets recorded in connection with acquisitions was $6.1 million and $4.8 million, respectively, for the years ended December 31, 2014 and 2013. Amortization expense included in technology and development for purchased data content intangible assets was $5.1 million and $2.8 million, respectively, for the years ended December 31, 2014 and 2013. Other data content expense was $0.7 million and $0.4 million, respectively, for the years ended December 31, 2014 and 2013.

General and Administrative

General and administrative expenses were $65.5 million for the year ended December 31, 2014 compared to $37.9 million for the year ended December 31, 2013, an increase of $27.6 million, or 73%. The increase in general and administrative expenses was a result of an $11.4 million increase in headcount-related expenses, including share-based compensation expense, driven primarily by growth in headcount and increases in compensation, a $5.0 million increase in building lease-related expenses including rent, utilities and insurance, a $4.7 million increase in professional services fees, including legal and accounting, a $2.1 million increase in travel and meals expense, a $1.8 million increase in city and state taxes, a $1.2 million increase in consulting costs, a $0.6 million increase in bad debt expense, a $0.2 million increase in software costs, and a $0.6 million increase in various other miscellaneous expenses.

Acquisition-Related Costs

Acquisition-related costs were $21.5 million for the year ended December 31, 2014 compared to $0.4 million for the year ended December 31, 2013, an increase of $21.1 million. Acquisition-related costs for the year ended December 31, 2014 were primarily a result of our proposed acquisition of Trulia, including investment banker, legal, accounting, tax, and regulatory filing fees. Acquisition-related costs for the year ended December 31, 2013 were a result of the acquisition of StreetEasy, Inc.

Income Taxes

During the years ended December 31, 2014 and 2013, we did not have a material amount of reportable taxable income. Therefore, no tax liability or expense has been recorded in the consolidated financial statements for the years ended December 31, 2014 and 2013.

We recorded an income tax benefit of $4.1 million for the year ended December 31, 2013 due to a deferred tax liability generated in connection with Zillow’s August 26, 2013 acquisition of StreetEasy, Inc. that can be used to realize certain deferred tax assets for which we had previously provided a full allowance.

Quarterly Results of Operations

The following tables set forth our unaudited quarterly statements of operations data for each of the periods presented below. In the opinion of management, the data has been prepared on the same basis as the audited consolidated financial statements included in this Annual Report on Form 10-K, and reflects all necessary adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of this data. The results of historical periods are not necessarily indicative of the results of operations of any future period. You should read this data together with our consolidated financial statements and the related notes included elsewhere in this Annual Report on Form 10-K. We have included Trulia, Inc. in Zillow Group’s results of operations

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prospectively after February 17, 2015, the date of acquisition. Our historical results are not necessarily indicative of our results to be expected in any future period. We have given retroactive effect to prior period share and per share amounts in our consolidated statements of operations for the August 2015 Class C Stock Split so that prior periods are comparable to current period presentation (see Note 14 of Part II, Item 8 of this Annual Report on Form 10-K for additional information related to the Class C Stock Split).

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The following tables present our revenue by type and as a percentage of total revenue for the periods presented: