The Company’s cash equivalents are classified within Level 1 and Level 2 of the fair value hierarchy. The Company’s investments in marketable securities are classified within Level 2 of the fair value hierarchy.

The fair values of the Company’s marketable securities are based on prices obtained from independent pricing sources. Consistent with the fair value hierarchy described in Note 2, Summary of Significant Accounting Policies, marketable securities with validated quotes from pricing services are reflected within Level 2, as they are primarily based on observable pricing for similar assets or other market observable inputs. Typical inputs used by these pricing services include, but are not limited to, reported trades, benchmark yields, issuer spreads, bids, offers or estimates of cash flow,

prepayment spreads and default rates. The Company performs validation procedures to ensure the reasonableness of this data. The Company performs its own review of prices received from the independent pricing services by comparing these prices to other sources. After completing the validation procedures, the Company did not adjust or override any fair value measurements provided by the pricing services as of June 30, 2023 and December 31, 2022.

The following tables summarize the Company’s cash equivalents and marketable securities as of June 30, 2023 and December 31, 2022:


	June 30, 2023
	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market funds	$	104,261	$	104,261	$	—	$	—
U.S. commercial paper		15,919		—		15,919		—
Total cash equivalents		120,180		104,261		15,919		—
Marketable securities:
U.S. government securities		227,933		—		227,933		—
U.S. corporate bonds		227,695		—		227,695		—
International corporate bonds		86,356		—		86,356		—
U.S. commercial paper		59,317		—		59,317		—
International commercial paper		100,870		—		100,870		—
U.S. certificates of deposit		13,893		—		13,893		—
U.S. municipal securities		165,136		—		165,136		—
Total marketable securities		881,200		—		881,200		—
	$	1,001,380	$	104,261	$	897,119	$	—


	December 31, 2022
	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market funds	$	161,185	$	161,185	$	—	$	—
Total cash equivalents		161,185		161,185		—		—
Marketable securities:
U.S. government securities		302,911		—		302,911		—
U.S. corporate bonds		354,495		—		354,495		—
International corporate bonds		127,248		—		127,248		—
U.S. commercial paper		63,114		—		63,114		—
International commercial paper		133,163		—		133,163		—
U.S. certificates of deposit		15,613		—		15,613		—
U.S. municipal securities		113,250		—		113,250		—
Total marketable securities		1,109,794		—		1,109,794		—
	$	1,270,979	$	161,185	$	1,109,794	$	—

During the six months ended June 30, 2023 and 2022, there were no transfers among the Level 1, Level 2 and Level 3 categories.

The following tables summarize the gross unrealized gains and losses of the Company’s marketable securities as of June 30, 2023 and December 31, 2022:


	June 30, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Assets:
U.S. government securities	$	229,757	$	2	$	(1,826	)	$	—	$	227,933
U.S. corporate bonds		229,502		3		(1,810	)		—		227,695
International corporate bonds		86,906		1		(551	)		—		86,356
U.S. commercial paper		59,392		—		(75	)		—		59,317
International commercial paper		101,055		—		(185	)		—		100,870
U.S. certificates of deposit		13,893		—		—			—		13,893
U.S. municipal securities		166,339		—		(1,203	)		—		165,136
	$	886,844	$	6	$	(5,650	)	$	—	$	881,200


	December 31, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Assets:
U.S. government securities	$	307,173	$	—	$	(4,262	)	$	—	$	302,911
U.S. corporate bonds		358,019		6		(3,530	)		—		354,495
International corporate bonds		128,374		7		(1,133	)		—		127,248
U.S. commercial paper		63,234		—		(120	)		—		63,114
International commercial paper		133,338		—		(175	)		—		133,163
U.S. certificates of deposit		15,613		—		—			—		15,613
U.S. municipal securities		114,249		31		(1,030	)		—		113,250
	$	1,120,000	$	44	$	(10,250	)	$	—	$	1,109,794

The following tables summarize the fair value and the unrealized losses of the Company’s marketable securities that have been in a loss position for either less than twelve months or greater than twelve months as of June 30, 2023 and December 31, 2022:


	June 30, 2023
	Less than 12 months					Greater than 12 months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(in thousands)
U.S. government securities	$	140,520	$	(804	)	$	72,484	$	(1,022	)	$	213,004	$	(1,826	)
U.S. corporate bonds		160,348		(1,130	)		47,918		(680	)		208,266		(1,810	)
International corporate bonds		69,198		(392	)		14,160		(159	)		83,358		(551	)
U.S. commercial paper		58,232		(75	)		—		—			58,232		(75	)
International commercial paper		83,020		(185	)		—		—			83,020		(185	)
U.S. municipal securities		145,520		(824	)		19,615		(379	)		165,135		(1,203	)
	$	656,838	$	(3,410	)	$	154,177	$	(2,240	)	$	811,015	$	(5,650	)


	December 31, 2022
	Less than 12 months					Greater than 12 months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(in thousands)
U.S. government securities	$	112,243	$	(1,517	)	$	185,691	$	(2,745	)	$	297,934	$	(4,262	)
U.S. corporate bonds		208,507		(1,989	)		130,633		(1,541	)		339,140		(3,530	)
International corporate bonds		50,982		(497	)		68,993		(636	)		119,975		(1,133	)
U.S. commercial paper		24,768		(120	)		—		—			24,768		(120	)
International commercial paper		30,987		(175	)		—		—			30,987		(175	)
U.S. municipal securities		86,251		(497	)		14,466		(533	)		100,717		(1,030	)
	$	513,738	$	(4,795	)	$	399,783	$	(5,455	)	$	913,521	$	(10,250	)

As of June 30, 2023 and December 31, 2022, the unrealized losses on the Company’s investments in U.S. government securities, U.S. corporate bonds, and international corporate bonds were caused by interest rate increases. The Company purchased those investments at a premium relative to their face amount. The current credit ratings are all within the guidelines of the investment policy of the Company and the Company does not expect the issuers to settle any security at a price less than the amortized cost basis of the investment. The Company does not intend to sell the investments and it is not probable that the Company will be required to sell the investments before recovery of their amortized cost basis.

As of June 30, 2023, all marketable securities held by the Company had remaining contractual maturities of one year or less, except for U.S. government securities, U.S. corporate bonds, international corporate bonds and municipal securities with a fair value of $144.5 million and maturities of one to two years.

As of December 31, 2022, all marketable securities held by the Company had remaining contractual maturities of one year or less, except for U.S. government securities, U.S. corporate bonds, international corporate bonds and municipal securities with a fair value of $211.2 million and maturities of one to two years.

All marketable securities, including those with remaining contractual maturities of more than one year, are classified as current assets on the balance sheet because they are considered to be “available for sale” and the Company can convert them into cash to fund current operations.

There have been no impairments of the Company’s assets measured and carried at fair value during the six months ended June 30, 2023 and the year ended December 31, 2022.