SEC. File Nos. 002-86838

811-03857

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

Registration Statement

Under

the Securities Act of 1933

Post-Effective Amendment No. 109

and

Registration Statement

Under

the Investment Company Act of 1940

Amendment No. 109

AMERICAN FUNDS INSURANCE SERIES

(Exact Name of Registrant as Specified in Charter)

333 South Hope Street

Los Angeles, California 90071-1406

(Address of Principal Executive Offices)

Registrant's telephone number, including area code:

(213) 486-9200

Courtney R. Taylor, Secretary

American Funds Insurance Series

333 South Hope Street

Los Angeles, California 90071-1406

(Name and Address of Agent for Service)

Copies to:

Lea Anne Copenhefer

Morgan, Lewis & Bockius LLP

One Federal Street

Boston, MA 02110-1726

(Counsel for the Registrant)

Approximate date of proposed public offering:

It is proposed that this filing become effective on May 1, 2026, pursuant to paragraph (a) of Rule 485.

SUBJECT TO COMPLETION, DATED FEBRUARY 27, 2026

THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE U.S. SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER TO SELL THESE SECURITIES AND IS NOT A SOLICITATION OF AN OFFER TO BUY THESE SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

American Funds Insurance Series® Prospectus Class 1 shares May 1, 2026

SMALLCAP World Fund

EUPAC Fund

Table of contents

The U.S. Securities and Exchange Commission has not approved or disapproved of these securities. Further, it has not determined that this prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

SMALLCAP World Fund

Investment objective The fund’s investment objective is to provide you with long-term growth of capital.

Fees and expenses of the fund This table describes the fees and expenses that you may pay if you buy, hold and sell an interest in Class 1 shares of the fund. You may pay other fees, such as insurance contract fees and expenses, which are not reflected in the tables and examples below. If insurance contract fees and expenses were reflected, expenses shown would be higher.

*  The investment adviser is currently waiving a portion of its management fee equal to 0.05% of the fund's net assets. This waiver will be in effect through at least May 1, 2027. The waiver may only be modified or terminated with the approval of the fund’s board.

Example This example is intended to help you compare the cost of investing in Class 1 shares of the fund with the cost of investing in other mutual funds.

The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the fund’s operating expenses remain the same. The example does not reflect insurance contract expenses. If insurance contract expenses were reflected, expenses shown would be higher. The example reflects the fee waiver described above through the expiration date of such waiver and total annual fund operating expenses thereafter. No sales charge (load) or other fees are charged by the fund upon redemption, so you would incur these hypothetical costs whether or not you were to redeem your shares at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio turnover The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund’s investment results. During the most recent fiscal year, the fund’s portfolio turnover rate was 51% of the average value of its portfolio.

Principal investment strategies Normally the fund invests at least 80% of its net assets in common stocks and other equity-type securities (such as preferred stocks, convertible preferred stocks and convertible bonds) of companies with small market capitalizations, including growth-oriented stocks. The investment adviser currently defines “small market capitalization” companies to be companies with market capitalizations within or below the capitalization range of companies included in the MSCI All Country World Small Cap Index or the Russell 2000 Index, measured based on the maximum market capitalization of companies in either index within the last 12 months. As of August 31, 2025, the largest company in the MSCI All Country World Small Cap Index had a market capitalization of approximately $25.9 billion and the largest company in the Russell 2000 Index had a market capitalization of approximately $20.9 billion. The market capitalization of the companies included in the MSCI All Country World Small Cap Index and the Russell 2000 Index will change with market conditions. The investment adviser has periodically re-evaluated and adjusted this definition and may continue to do so in the future. The fund may continue to hold securities of a portfolio company that subsequently appreciates above the small market capitalization threshold. Under normal circumstances, the fund will invest a significant portion of its assets outside the United States, including in emerging markets.

Prior to May 1, 2026, the fund was called Global Small Capitalization Fund.

The investment adviser uses a system of multiple portfolio managers in managing the fund’s assets. Under this approach, the portfolio of the fund is divided into segments managed by individual managers.

The fund relies on the professional judgment of its investment adviser to make decisions about the fund’s portfolio investments. The basic investment philosophy of the investment adviser is to seek to invest in attractively valued companies that, in its opinion, represent good, long-term investment opportunities. Securities may be sold when the investment adviser believes that they no longer represent relatively attractive investment opportunities.

1     American Funds Insurance Series / Prospectus

Principal risks This section describes the principal risks associated with investing in the fund. You may lose money by investing in the fund. The likelihood of loss may be greater if you invest for a shorter period of time.

Market conditions — The prices of, and the income generated by, the securities held by the fund may decline – sometimes rapidly or unpredictably – due to various factors, including events or conditions affecting the general economy or particular industries or companies; overall market changes; local, regional or global political, social or economic instability; governmental, governmental agency or central bank responses to economic conditions; levels of public debt and deficits; changes in inflation rates; and currency exchange rate, interest rate and commodity price fluctuations.

Economies and financial markets throughout the world are highly interconnected. Economic, financial or political events, trading and tariff arrangements, wars, terrorism, cybersecurity events, natural disasters, public health emergencies (such as the spread of infectious disease), bank failures and other circumstances in one country or region, including actions taken by governmental or quasi-governmental authorities in response to any of the foregoing, could have impacts on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries affected, the value and liquidity of the fund’s investments may be negatively affected by developments in other countries and regions.

Issuer risks — The prices of, and the income generated by, securities held by the fund may decline in response to various factors directly related to the issuers of such securities, including reduced demand for an issuer’s goods or services, poor management performance, major litigation, investigations or other controversies related to the issuer, changes in the issuer’s financial condition or credit rating, changes in government regulations affecting the issuer or its competitive environment and strategic initiatives such as mergers, acquisitions or dispositions and the market response to any such initiatives. An individual security may also be affected by factors relating to the industry or sector of the issuer or the securities markets as a whole, and conversely an industry or sector or the securities markets may be affected by a change in financial condition or other event affecting a single issuer.

Investing in growth-oriented stocks — Growth-oriented common stocks and other equity-type securities (such as preferred stocks, convertible preferred stocks and convertible bonds) may involve larger price swings and greater potential for loss than other types of investments. These risks may be even greater in the case of smaller capitalization stocks.

Investing in small companies — Investing in smaller companies may pose additional risks. For example, it is often more difficult to value or dispose of small company stocks and more difficult to obtain information about smaller companies than about larger companies. Furthermore, smaller companies often have limited product lines, operating histories, markets and/or financial resources, may be dependent on one or a few key persons for management, and can be more susceptible to losses. Moreover, the prices of their stocks may be more volatile than stocks of larger, more established companies, particularly during times of market turmoil.

Investing outside the United States — Securities of issuers domiciled outside the United States or with significant operations or revenues outside the United States, and securities tied economically to countries outside the United States, may lose value because of adverse political, social, economic or market developments (including social instability, regional conflicts, terrorism and war) in the countries or regions in which the issuers are domiciled, operate or generate revenue or to which the securities are tied economically. These securities may also lose value due to changes in foreign currency exchange rates against the U.S. dollar and/or currencies of other countries. Issuers of these securities may be more susceptible to actions of foreign governments, such as nationalization, currency blockage or the imposition of price controls, sanctions, or punitive taxes, each of which could adversely impact the value of these securities. Securities markets in certain countries may be more volatile and/or less liquid than those in the United States. Investments outside the United States may also be subject to different regulatory, legal, accounting, auditing, financial reporting and recordkeeping requirements, and may be more difficult to value, than those in the United States. In addition, the value of investments outside the United States may be reduced by foreign taxes, including foreign withholding taxes on interest and dividends. Further, there may be increased risks of delayed settlement of securities purchased or sold by the fund, which could impact the liquidity of the fund’s portfolio. The risks of investing outside the United States may be heightened in connection with investments in emerging markets.

Investing in emerging markets — Investing in emerging markets may involve risks in addition to and greater than those generally associated with investing in the securities markets of developed countries. For instance, emerging market countries tend to have less developed political, economic and legal systems than those in developed countries. Accordingly, the governments of these countries may be less stable and more likely to intervene in the market economy, for example, by imposing capital controls, nationalizing a company or industry, placing restrictions on foreign ownership and on withdrawing sale proceeds of securities from the country, and/or imposing punitive taxes that could adversely affect the prices of securities. Information regarding issuers in emerging markets may be limited, incomplete or inaccurate, and such issuers may not be subject to regulatory, accounting, auditing, and financial reporting and recordkeeping standards comparable to those to which issuers in more developed markets are subject. The fund’s rights with respect to its investments in emerging markets, if any, will generally be governed by local law, which may make it difficult or impossible for the fund to pursue legal remedies or to obtain and enforce judgments in local courts. In addition, the economies of these countries may be dependent on relatively few industries, may have limited access to capital and may be more susceptible to changes in local and global trade conditions and downturns in the world economy. Securities markets in these countries can also be relatively small and have substantially lower trading volumes. As a result, securities issued in these countries may be more volatile and less liquid, more vulnerable to market manipulation, and more difficult to value, than securities issued in countries with more developed economies and/or markets. Less certainty with respect to security valuations may lead to additional challenges and risks in calculating the fund’s net asset value. Additionally, emerging markets are more likely to experience problems with the clearing and settling of trades and the holding of securities by banks, agents and depositories that are less established than those in developed countries.

American Funds Insurance Series / Prospectus     2

Liquidity risk — Certain fund holdings may be or may become difficult or impossible to sell, particularly during times of market turmoil. Liquidity may be impacted by the lack of an active market for a holding, legal or contractual restrictions on resale, or the reduced number and capacity of market participants to make a market in such holding. Market prices for less liquid or illiquid holdings may be volatile or difficult to determine, and reduced liquidity may have an adverse impact on the market price of such holdings. Additionally, the sale of less liquid or illiquid holdings may involve substantial delays (including delays in settlement) and additional costs and the fund may be unable to sell such holdings when necessary to meet its liquidity needs or to try to limit losses, or may be forced to sell at a loss.

Management — The investment adviser to the fund actively manages the fund’s investments. Consequently, the fund is subject to the risk that the methods and analyses, including models, tools and data, employed by the investment adviser in this process may be flawed or incorrect and may not produce the desired results. This could cause the fund to lose value or its investment results to lag relevant benchmarks or other funds with similar objectives.

Your investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency, entity or person. You should consider how this fund fits into your overall investment program.

Investment results The following bar chart shows how the investment results of the Class 1 shares of the fund have varied from year to year, and the following table shows how the fund’s average annual total returns for various periods compare with a broad measure of securities market results and, if applicable, other measures of market results that reflect the fund’s investment universe. This information provides some indication of the risks of investing in the fund. Past investment results (before and after taxes) are not predictive of future investment results. Figures shown reflect fees and expenses associated with an investment in the fund, but do not reflect insurance contract fees and expenses. If insurance contract fees and expenses were included, results would have been lower. Updated information on the fund’s investment results can be obtained by visiting capitalgroup.com/afis.

3     American Funds Insurance Series / Prospectus

Management

Investment adviser Capital Research and Management Company
Portfolio managers The individuals primarily responsible for the portfolio management of the fund are:

Purchase and sale of fund shares Shares of the fund are not sold directly to the general public. The fund is offered only as an underlying investment option for variable insurance contracts, and insurance company separate accounts and qualified feeder funds — and not the holders of variable insurance contracts — are the shareholders of the fund. Although the fund does not require a minimum amount for initial or subsequent purchases from insurance companies, your insurance company may impose investment minimums for your purchase of the fund.

You may sell (redeem) shares on any business day. You must sell (redeem) shares through your insurance company.

Tax information See your variable insurance contract prospectus for information regarding the federal income tax treatment of your variable insurance contract and related distributions.

Payments to broker-dealers and other financial intermediaries The fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) for distribution and/or other services. These payments may be a factor that the insurance company considers in including the fund as an underlying investment option in the variable insurance contract. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

American Funds Insurance Series / Prospectus     4

EUPAC Fund

Investment objective The fund’s investment objective is to provide you with long-term growth of capital.

Fees and expenses of the fund This table describes the fees and expenses that you may pay if you buy, hold and sell an interest in Class 1 shares of the fund. You may pay other fees, such as insurance contract fees and expenses, which are not reflected in the tables and examples below. If insurance contract fees and expenses were reflected, expenses shown would be higher.

*  The investment adviser is currently waiving a portion of its management fee equal to 0.06% of the fund's net assets. This waiver will be in effect through at least May 1, 2027. The waiver may only be modified or terminated with the approval of the fund’s board.

Example This example is intended to help you compare the cost of investing in Class 1 shares of the fund with the cost of investing in other mutual funds.

The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the fund’s operating expenses remain the same. The example does not reflect insurance contract expenses. If insurance contract expenses were reflected, expenses shown would be higher. The example reflects the fee waiver described above through the expiration date of such waiver and total annual fund operating expenses thereafter. No sales charge (load) or other fees are charged by the fund upon redemption, so you would incur these hypothetical costs whether or not you were to redeem your shares at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio turnover The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund’s investment results. During the most recent fiscal year, the fund’s portfolio turnover rate was 63% of the average value of its portfolio.

Principal investment strategies The fund invests primarily in common stocks in Europe and the Pacific Basin that the investment adviser believes have the potential for growth. Growth stocks are stocks that the investment adviser believes have the potential for above-average capital appreciation.

Normally the fund will invest at least 80% of its net assets in securities of issuers in Europe and the Pacific Basin. A country will be considered part of Europe if it is part of the MSCI European indexes, and part of the Pacific Basin if any of its borders touches the Pacific Ocean. In determining the domicile of an issuer, the fund’s investment adviser will generally look to the determination of MSCI Inc. (MSCI) for equity securities and Bloomberg for debt securities. In certain limited circumstances (including where relevant data is unavailable or the nature of a holding warrants special considerations), the adviser may also take into account additional factors, as applicable, including where the issuer’s securities are listed; where the issuer is legally organized, maintains principal corporate offices, conducts its principal operations, generates revenues and/or has credit risk exposure; and the source of guarantees, if any, of such securities. The fund may invest a portion of its assets in common stocks and other securities of companies in emerging markets.

Prior to May 1, 2026, the fund was called International Fund.

The investment adviser uses a system of multiple portfolio managers in managing the fund’s assets. Under this approach, the portfolio of the fund is divided into segments managed by individual managers.

The fund relies on the professional judgment of its investment adviser to make decisions about the fund’s portfolio investments. The basic investment philosophy of the investment adviser is to seek to invest in attractively valued companies that, in its opinion, represent good, long-term investment opportunities. Securities may be sold when the investment adviser believes that they no longer represent relatively attractive investment opportunities.

5     American Funds Insurance Series / Prospectus

Principal risks This section describes the principal risks associated with investing in the fund. You may lose money by investing in the fund. The likelihood of loss may be greater if you invest for a shorter period of time.

Market conditions — The prices of, and the income generated by, the common stocks and other securities held by the fund may decline – sometimes rapidly or unpredictably – due to various factors, including events or conditions affecting the general economy or particular industries or companies; overall market changes; local, regional or global political, social or economic instability; governmental, governmental agency or central bank responses to economic conditions; levels of public debt and deficits; changes in inflation rates; and currency exchange rate, interest rate and commodity price fluctuations.

Economies and financial markets throughout the world are highly interconnected. Economic, financial or political events, trading and tariff arrangements, wars, terrorism, cybersecurity events, natural disasters, public health emergencies (such as the spread of infectious disease), bank failures and other circumstances in one country or region, including actions taken by governmental or quasi-governmental authorities in response to any of the foregoing, could have impacts on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries affected, the value and liquidity of the fund’s investments may be negatively affected by developments in other countries and regions.

Issuer risks — The prices of, and the income generated by, securities held by the fund may decline in response to various factors directly related to the issuers of such securities, including reduced demand for an issuer’s goods or services, poor management performance, major litigation, investigations or other controversies related to the issuer, changes in the issuer’s financial condition or credit rating, changes in government regulations affecting the issuer or its competitive environment and strategic initiatives such as mergers, acquisitions or dispositions and the market response to any such initiatives. An individual security may also be affected by factors relating to the industry or sector of the issuer or the securities markets as a whole, and conversely an industry or sector or the securities markets may be affected by a change in financial condition or other event affecting a single issuer.

Investing in growth-oriented stocks — Growth-oriented common stocks and other equity-type securities (such as preferred stocks, convertible preferred stocks and convertible bonds) may involve larger price swings and greater potential for loss than other types of investments. These risks may be even greater in the case of smaller capitalization stocks.

Investing outside the United States — Securities of issuers domiciled outside the United States or with significant operations or revenues outside the United States, and securities tied economically to countries outside the United States, may lose value because of adverse political, social, economic or market developments (including social instability, regional conflicts, terrorism and war) in the countries or regions in which the issuers are domiciled, operate or generate revenue or to which the securities are tied economically. These securities may also lose value due to changes in foreign currency exchange rates against the U.S. dollar and/or currencies of other countries. Issuers of these securities may be more susceptible to actions of foreign governments, such as nationalization, currency blockage or the imposition of price controls, sanctions, or punitive taxes, each of which could adversely impact the value of these securities. Securities markets in certain countries may be more volatile and/or less liquid than those in the United States. Investments outside the United States may also be subject to different regulatory, legal, accounting, auditing, financial reporting and recordkeeping requirements, and may be more difficult to value, than those in the United States. In addition, the value of investments outside the United States may be reduced by foreign taxes, including foreign withholding taxes on interest and dividends. Further, there may be increased risks of delayed settlement of securities purchased or sold by the fund, which could impact the liquidity of the fund’s portfolio. The risks of investing outside the United States may be heightened in connection with investments in emerging markets.

Investing in emerging markets — Investing in emerging markets may involve risks in addition to and greater than those generally associated with investing in the securities markets of developed countries. For instance, emerging market countries tend to have less developed political, economic and legal systems than those in developed countries. Accordingly, the governments of these countries may be less stable and more likely to intervene in the market economy, for example, by imposing capital controls, nationalizing a company or industry, placing restrictions on foreign ownership and on withdrawing sale proceeds of securities from the country, and/or imposing punitive taxes that could adversely affect the prices of securities. Information regarding issuers in emerging markets may be limited, incomplete or inaccurate, and such issuers may not be subject to regulatory, accounting, auditing, and financial reporting and recordkeeping standards comparable to those to which issuers in more developed markets are subject. The fund’s rights with respect to its investments in emerging markets, if any, will generally be governed by local law, which may make it difficult or impossible for the fund to pursue legal remedies or to obtain and enforce judgments in local courts. In addition, the economies of these countries may be dependent on relatively few industries, may have limited access to capital and may be more susceptible to changes in local and global trade conditions and downturns in the world economy. Securities markets in these countries can also be relatively small and have substantially lower trading volumes. As a result, securities issued in these countries may be more volatile and less liquid, more vulnerable to market manipulation, and more difficult to value, than securities issued in countries with more developed economies and/or markets. Less certainty with respect to security valuations may lead to additional challenges and risks in calculating the fund’s net asset value. Additionally, emerging markets are more likely to experience problems with the clearing and settling of trades and the holding of securities by banks, agents and depositories that are less established than those in developed countries.

Management — The investment adviser to the fund actively manages the fund’s investments. Consequently, the fund is subject to the risk that the methods and analyses, including models, tools and data, employed by the investment adviser in this process may be flawed or incorrect and may not produce the desired results. This could cause the fund to lose value or its investment results to lag relevant benchmarks or other funds with similar objectives.

Your investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency, entity or person. You should consider how this fund fits into your overall investment program.

American Funds Insurance Series / Prospectus     6

Investment results The following bar chart shows how the investment results of the Class 1 shares of the fund have varied from year to year, and the following table shows how the fund’s average annual total returns for various periods compare with a broad measure of securities market results and, if applicable, other measures of market results that reflect the fund’s investment universe. This information provides some indication of the risks of investing in the fund. Past investment results (before and after taxes) are not predictive of future investment results. Figures shown reflect fees and expenses associated with an investment in the fund, but do not reflect insurance contract fees and expenses. If insurance contract fees and expenses were included, results would have been lower. Updated information on the fund’s investment results can be obtained by visiting capitalgroup.com/afis.

Management

Investment adviser Capital Research and Management Company
Portfolio managers The individuals primarily responsible for the portfolio management of the fund are:

Purchase and sale of fund shares Shares of the fund are not sold directly to the general public. The fund is offered only as an underlying investment option for variable insurance contracts, and insurance company separate accounts and qualified feeder funds — and not the holders of variable insurance contracts — are the shareholders of the fund. Although the fund does not require a minimum amount for initial or subsequent purchases from insurance companies, your insurance company may impose investment minimums for your purchase of the fund.

You may sell (redeem) shares on any business day. You must sell (redeem) shares through your insurance company.

Tax information See your variable insurance contract prospectus for information regarding the federal income tax treatment of your variable insurance contract and related distributions.

Payments to broker-dealers and other financial intermediaries The fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) for distribution and/or other services. These payments may be a factor that the insurance company considers in including the fund as an underlying investment option in the variable insurance contract. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

7     American Funds Insurance Series / Prospectus

Investment objectives, strategies and risks

SMALLCAP World Fund The fund’s investment objective is to provide you with long-term growth of capital. While it has no present intention to do so, the fund’s board may change the fund’s investment objective without shareholder approval upon 60 days’ prior written notice to shareholders. Normally the fund invests at least 80% of its net assets in common stocks and other equity-type securities (such as preferred stocks, convertible preferred stocks and convertible bonds) of companies with small market capitalizations, including growth-oriented stocks. This policy is subject to change only upon 60 days’ prior written notice to shareholders. The investment adviser currently defines “small market capitalization” companies to be companies with market capitalizations within or below the capitalization range of companies included in the MSCI All Country World Small Cap Index or the Russell 2000 Index, measured based on the maximum market capitalization of companies in either index within the last 12 months. As of August 31, 2025, the largest company in the MSCI All Country World Small Cap Index had a market capitalization of approximately $25.9 billion and the largest company in the Russell 2000 Index had a market capitalization of approximately $20.9 billion. The market capitalization of the companies included in the MSCI All Country World Small Cap Index and the Russell 2000 Index will change with market conditions. The investment adviser has periodically re-evaluated and adjusted this definition and may continue to do so in the future. The fund may continue to hold securities of a portfolio company that subsequently appreciates above the small market capitalization threshold. Under normal circumstances, the fund will invest a significant portion of its assets outside the United States, including in emerging markets.

The fund may also hold cash or cash equivalents, including commercial paper and short-term securities issued by the U.S. government, its agencies and instrumentalities. The percentage of the fund invested in such holdings varies and depends on various factors, including market conditions and purchases and redemptions of fund shares. The investment adviser may determine that it is appropriate to invest a substantial portion of the fund’s assets in such instruments in response to certain circumstances, such as periods of market turmoil. For temporary defensive purposes, the fund may invest without limitation in such instruments. A larger percentage of such holdings could moderate the fund’s investment results in a period of rising market prices. Alternatively, a larger percentage of such holdings could reduce the magnitude of the fund’s loss in a period of falling market prices and provide liquidity to make additional investments or to meet redemptions.

The fund may invest in certain other funds managed by the investment adviser or its affiliates (“Central Funds”) to more effectively invest in a diversified set of securities in a specific asset class such as money market instruments, bonds and other securities. Shares of Central Funds are only offered for purchase to the fund’s investment adviser and its affiliates and other funds, investment vehicles and accounts managed by the fund’s investment adviser and its affiliates. Central Funds do not charge management fees. As a result, the fund does not bear additional management fees when investing in Central Funds, but the fund does bear its proportionate share of Central Fund expenses. The investment results of the portions of the fund’s assets invested in the Central Funds will be based upon the investment results of the Central Funds.

The fund may also lend portfolio securities to brokers, dealers and other institutions that provide cash or U.S. Treasury securities as collateral in an amount at least equal to the value of the securities loaned.

Prior to May 1, 2026, the fund was called Global Small Capitalization Fund.

The fund relies on the professional judgment of its investment adviser to make decisions about the fund’s portfolio investments. The basic investment philosophy of the investment adviser is to seek to invest in attractively valued companies that, in its opinion, represent good, long-term investment opportunities. The investment adviser believes that an important way to accomplish this is through fundamental analysis, which may include meeting with company executives and employees, suppliers, customers and competitors. Securities may be sold when the investment adviser believes that they no longer represent relatively attractive investment opportunities.

The investment adviser may consider environmental, social and governance (“ESG”) factors that, depending on the facts and circumstances, are material to the value of an issuer or instrument. ESG factors may include, but are not limited to, environmental issues (e.g., water use, emission levels, waste, environmental remediation), social issues (e.g., human capital, health and safety, changing customer behavior) or governance issues (e.g., board composition, executive compensation, shareholder dilution).

The following are principal risks associated with investing in the fund.

Market conditions — The prices of, and the income generated by, the securities held by the fund may decline – sometimes rapidly or unpredictably – due to various factors, including events or conditions affecting the general economy or particular industries or companies; overall market changes; local, regional or global political, social or economic instability; governmental, governmental agency or central bank responses to economic conditions; levels of public debt and deficits; changes in inflation rates; and currency exchange rate, interest rate and commodity price fluctuations.

Economies and financial markets throughout the world are highly interconnected. Economic, financial or political events, trading and tariff arrangements, wars, terrorism, cybersecurity events, natural disasters, public health emergencies (such as the spread of infectious disease), bank failures and other circumstances in one country or region, including actions taken by governmental or quasi-governmental authorities in response to any of the foregoing, could have impacts on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries affected, the value and liquidity of the fund’s investments may be negatively affected by developments in other countries and regions.

Issuer risks — The prices of, and the income generated by, securities held by the fund may decline in response to various factors directly related to the issuers of such securities, including reduced demand for an issuer’s goods or services, poor management performance, major litigation, investigations or other controversies related to the issuer, changes in the issuer’s financial condition or credit rating, changes in government regulations affecting the issuer or its competitive environment and strategic initiatives such as mergers, acquisitions or dispositions and the market response to any such initiatives. An individual security may also be affected by factors relating to the industry or sector of the issuer or the securities markets as a whole, and conversely an industry or sector or the securities markets

American Funds Insurance Series / Prospectus     8

may be affected by a change in financial condition or other event affecting a single issuer. To the extent that the market prices of securities of issuers in the same or related industries or sectors tend to move in the same direction at the same time, and these issuers make up a sizeable portion of the market, events affecting one issuer, industry or sector or the securities markets generally may have a larger impact. If such issuers represent a substantial portion of major market indices, or the economy, a downturn in the prices of their securities may have a disproportionate adverse effect on the overall market, even if other segments of the market perform well. The fund’s portfolio managers invest in issuers based on their level of investment conviction. At times, the fund may invest more significantly in a single issuer, which could increase the fund’s volatility and the risk of loss arising from the factors described above.

Investing in growth-oriented stocks — Growth-oriented common stocks and other equity-type securities (such as preferred stocks, convertible preferred stocks and convertible bonds) may involve larger price swings and greater potential for loss than other types of investments. These risks may be even greater in the case of smaller capitalization stocks.

Investing in small companies — Investing in smaller companies may pose additional risks. For example, it is often more difficult to value or dispose of small company stocks and more difficult to obtain information about smaller companies than about larger companies. Furthermore, smaller companies often have limited product lines, operating histories, markets and/or financial resources, may be dependent on one or a few key persons for management, and can be more susceptible to losses. Moreover, the prices of their stocks may be more volatile than stocks of larger, more established companies, particularly during times of market turmoil.

Investing outside the United States — Securities of issuers domiciled outside the United States or with significant operations or revenues outside the United States, and securities tied economically to countries outside the United States, may lose value because of adverse political, social, economic or market developments (including social instability, regional conflicts, terrorism and war) in the countries or regions in which the issuers are domiciled, operate or generate revenue or to which the securities are tied economically. These securities may also lose value due to changes in foreign currency exchange rates against the U.S. dollar and/or currencies of other countries. Issuers of these securities may be more susceptible to actions of foreign governments, such as nationalization, currency blockage or the imposition of price controls, sanctions, or punitive taxes, each of which could adversely impact the value of these securities. Securities markets in certain countries may be more volatile and/or less liquid than those in the United States. Investments outside the United States may also be subject to different regulatory, legal, accounting, auditing, financial reporting and recordkeeping requirements, and may be more difficult to value, than those in the United States. In addition, the value of investments outside the United States may be reduced by foreign taxes, including foreign withholding taxes on interest and dividends. Further, there may be increased risks of delayed settlement of securities purchased or sold by the fund, which could impact the liquidity of the fund’s portfolio. The risks of investing outside the United States may be heightened in connection with investments in emerging markets.

Investing in emerging markets — Investing in emerging markets may involve risks in addition to and greater than those generally associated with investing in the securities markets of developed countries. For instance, emerging market countries tend to have less developed political, economic and legal systems than those in developed countries. Accordingly, the governments of these countries may be less stable and more likely to intervene in the market economy, for example, by imposing capital controls, nationalizing a company or industry, placing restrictions on foreign ownership and on withdrawing sale proceeds of securities from the country, and/or imposing punitive taxes that could adversely affect the prices of securities. Information regarding issuers in emerging markets may be limited, incomplete or inaccurate, and such issuers may not be subject to regulatory, accounting, auditing, and financial reporting and recordkeeping standards comparable to those to which issuers in more developed markets are subject. The fund’s rights with respect to its investments in emerging markets, if any, will generally be governed by local law, which may make it difficult or impossible for the fund to pursue legal remedies or to obtain and enforce judgments in local courts. In addition, the economies of these countries may be dependent on relatively few industries, may have limited access to capital and may be more susceptible to changes in local and global trade conditions and downturns in the world economy. Securities markets in these countries can also be relatively small and have substantially lower trading volumes. As a result, securities issued in these countries may be more volatile and less liquid, more vulnerable to market manipulation, and more difficult to value, than securities issued in countries with more developed economies and/or markets. Less certainty with respect to security valuations may lead to additional challenges and risks in calculating the fund’s net asset value. Additionally, emerging markets are more likely to experience problems with the clearing and settling of trades and the holding of securities by banks, agents and depositories that are less established than those in developed countries.

Liquidity risk — Certain fund holdings may be or may become difficult or impossible to sell, particularly during times of market turmoil. Liquidity may be impacted by the lack of an active market for a holding, legal or contractual restrictions on resale, or the reduced number and capacity of market participants to make a market in such holding. Market prices for less liquid or illiquid holdings may be volatile or difficult to determine, and reduced liquidity may have an adverse impact on the market price of such holdings. Additionally, the sale of less liquid or illiquid holdings may involve substantial delays (including delays in settlement) and additional costs and the fund may be unable to sell such holdings when necessary to meet its liquidity needs or to try to limit losses, or may be forced to sell at a loss.

Management — The investment adviser to the fund actively manages the fund’s investments. Consequently, the fund is subject to the risk that the methods and analyses, including models, tools and data, employed by the investment adviser in this process may be flawed or incorrect and may not produce the desired results. This could cause the fund to lose value or its investment results to lag relevant benchmarks or other funds with similar objectives.

The following are additional risks associated with investing in the fund.

Exposure to country, region, industry or sector — Subject to the fund’s investment limitations, the fund may have significant exposure to a particular country, region, industry or sector. Such exposure may cause the fund to be more impacted by risks relating to and developments affecting the country, region, industry or sector, and thus its net asset value may be more volatile, than a fund without such

9     American Funds Insurance Series / Prospectus

levels of exposure. For example, if the fund has significant exposure in a particular country, then social, economic, regulatory or other issues that negatively affect that country may have a greater impact on the fund than on a fund that is more geographically diversified.

Lending of portfolio securities — Securities lending involves risks, including the risk that the loaned securities may not be returned in a timely manner or at all, which would interfere with the fund’s ability to vote proxies or settle transactions, and/or the risk of a counterparty default. Additionally, the fund may lose money from the reinvestment of collateral received on loaned securities in investments that decline in value, default or do not perform as expected.

Cybersecurity breaches — The fund may be subject to operational and information security risks through breaches in cybersecurity. Cybersecurity breaches can result from deliberate attacks or unintentional events, including “ransomware” attacks, the injection of computer viruses or malicious software code, the use of vulnerabilities in code to gain unauthorized access to digital information systems, networks or devices, or external attacks such as denial-of-service attacks on the investment adviser’s or an affiliate’s website that could render the fund’s network services unavailable to intended end-users. These breaches may, among other things, lead to the unauthorized release of confidential information, misuse of the fund’s assets or sensitive information, the disruption of the fund’s operational capacity, the inability of fund shareholders to transact business, or the destruction of the fund’s physical infrastructure, equipment or operating systems. These events could cause the fund to violate applicable privacy and other laws and could subject the fund to reputational damage, additional costs associated with corrective measures and/or financial loss. The fund may also be subject to additional risks if its third-party service providers, such as the fund’s investment adviser, transfer agent, custodian, administrators and other financial intermediaries, experience similar cybersecurity breaches and potential outcomes. Cybersecurity risks may also impact issuers of securities in which the fund invests, which may cause the fund’s investments in such issuers to lose value.

Large shareholder transactions risk — The fund may experience adverse effects when shareholders, including other funds or accounts advised by the investment adviser, purchase or redeem, individually or in the aggregate, large amounts of shares relative to the size of the fund. For example, when the investment adviser changes allocations in other funds and accounts it manages, such changes may result in shareholder transactions in the fund that are large relative to the size of the fund. Such large shareholder redemptions may cause the fund to sell portfolio securities at times when it would not otherwise do so, which may negatively impact the fund’s net asset value and liquidity. Similarly, large fund share purchases may adversely affect the fund’s performance to the extent that the fund is delayed in investing new cash and is required to maintain a larger cash position than it ordinarily would. These transactions may also accelerate the realization of taxable income to shareholders if such sales of investments resulted in gains, and may also increase transaction costs. In addition, a large redemption could result in the fund’s current expenses being allocated over a smaller asset base, leading to an increase in the fund’s expense ratio. These risks are heightened when the fund is small.

In addition to the principal investment strategies described above, the fund has other investment practices that are described in the statement of additional information, which includes a description of other risks related to the fund’s principal investment strategies and other investment practices. The fund’s investment results will depend on the ability of the fund’s investment adviser to navigate the risks discussed above as well as those described in the statement of additional information.

Fund comparative indexes — The MSCI ACWI IMI Index is a free float-adjusted market capitalization-weighted index that is designed to measure the equity market results of large, mid, and small capitalization companies in both developed and emerging markets. The index consists of more than 40 developed and emerging market country indexes. Results reflect dividends net of withholding taxes. This index is unmanaged, and its results include reinvested dividends and/or distributions but do not reflect the effect of sales charges, commissions, account fees, expenses or U.S. federal income taxes.The MSCI All Country World Small Cap Index is a free float-adjusted market capitalization-weighted index that is designed to measure equity market results of smaller capitalization companies in both developed and emerging markets. Results reflect dividends net of withholding taxes. This index is unmanaged, and its results include reinvested dividends and/or distributions but do not reflect the effect of sales charges, commissions, account fees, expenses or U.S. federal income taxes.

Portfolio holdings A description of the fund’s policies and procedures regarding disclosure of information about its portfolio holdings is available in the statement of additional information.

EUPAC Fund The fund’s investment objective is to provide you with long-term growth of capital. While it has no present intention to do so, the fund’s board may change the fund’s investment objective without shareholder approval upon 60 days’ written notice to shareholders.

The fund is designed for investors seeking capital appreciation and diversification through investments in common stocks and other equity-type securities (including depositary receipts), consistent with the fund’s investment objective.

Investors in the fund should have a long-term perspective and be able to tolerate potentially sharp declines in value.

The following describes certain strategies that the investment adviser uses in pursuit of the fund’s investment objective and the corresponding risks:

The fund invests primarily in common stocks in Europe and the Pacific Basin that the investment adviser believes have the potential for growth. Growth stocks are stocks that the investment adviser believes have the potential for above-average capital appreciation.

Normally, the fund will invest at least 80% of its net assets in securities of issuers in Europe and the Pacific Basin. This policy is subject to change only upon 60 days’ notice to shareholders. A country will be considered part of Europe if it is part of the MSCI European indexes, and part of the Pacific Basin if any of its borders touches the Pacific Ocean. In determining the domicile of an issuer, the fund’s investment adviser will generally look to the determination of MSCI Inc. (MSCI) for equity securities and Bloomberg for debt securities. In certain limited circumstances (including where relevant data is unavailable or the nature of a holding warrants special considerations), the adviser may also take into account additional factors, as applicable, including where the issuer’s securities are listed; where the issuer is legally

American Funds Insurance Series / Prospectus     10

organized, maintains principal corporate offices, conducts its principal operations, generates revenues and/or has credit risk exposure; and the source of guarantees, if any, of such securities. The fund may invest a portion of its assets in common stocks and other securities of companies in emerging markets.

The fund may also hold cash, cash equivalents and fixed-income securities, including commercial paper and short-term securities issued by the U.S. government, its agencies and instrumentalities. The percentage of the fund invested in such holdings varies and depends on various factors, including market conditions and purchases and redemptions of fund shares. The investment adviser may determine that it is appropriate to invest a substantial portion of the fund’s assets in such instruments in response to certain circumstances, such as periods of market turmoil. For temporary defensive purposes, the fund may invest without limitation in such instruments. A larger percentage of such holdings could moderate the fund’s investment results in a period of rising market prices. Alternatively, a larger percentage of such holdings could reduce the magnitude of the fund’s loss in a period of falling market prices and provide liquidity to make additional investments or to meet redemptions.

The fund may invest in certain other funds managed by the investment adviser or its affiliates (“Central Funds”) to more effectively invest in a diversified set of securities in a specific asset class such as money market instruments, bonds and other securities. Shares of Central Funds are only offered for purchase to the fund’s investment adviser and its affiliates and other funds, investment vehicles and accounts managed by the fund’s investment adviser and its affiliates. Central Funds do not charge management fees. As a result, the fund does not bear additional management fees when investing in Central Funds, but the fund does bear its proportionate share of Central Fund expenses. The investment results of the portions of the fund’s assets invested in the Central Funds will be based upon the investment results of the Central Funds.

The fund may also lend portfolio securities to brokers, dealers and other institutions that provide cash or U.S. Treasury securities as collateral in an amount at least equal to the value of the securities loaned.

Prior to May 1, 2026, the fund was called International Fund.