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, 2022 and December 31, 2021.

The following tables summarize the Company’s cash equivalents and marketable securities as of June 30, 2022 and December 31, 2021.

	June 30, 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	$	202,519	$	202,519	$	—	$	—
International corporate bonds		2,599		—		2,599		—
Total cash equivalents		205,118		202,519		2,599		—
Marketable securities:
U.S. government securities		402,639		—		402,639		—
U.S. corporate bonds		494,017		—		494,017		—
International corporate bonds		165,396		—		165,396		—
U.S. commercial paper		74,037		—		74,037		—
International commercial paper		113,854		—		113,854		—
U.S. certificates of deposit		19,981		—		19,981		—
U.S. municipal securities		37,273		—		37,273		—
Total marketable securities		1,307,197		—		1,307,197		—
	$	1,512,315	$	202,519	$	1,309,796	$	—

	December 31, 2021
	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	$	289,440	$	289,440	$	—	$	—
U.S. commercial paper		2,000		—		2,000		—
International commercial paper		1,999		—		1,999		—
Total cash equivalents		293,439		289,440		3,999		—
Marketable securities:
U.S. government securities		324,532		—		324,532		—
U.S. corporate bonds		627,780		—		627,780		—
International corporate bonds		236,812		—		236,812		—
U.S. commercial paper		80,176		—		80,176		—
International commercial paper		142,335		—		142,335		—
U.S. municipal securities		36,428		—		36,428		—
Total marketable securities		1,448,063		—		1,448,063		—
	$	1,741,502	$	289,440	$	1,452,062	$	—

During the six months ended June 30, 2022 and 2021, 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, 2022 and December 31, 2021:

	June 30, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Assets:
U.S. government securities	$	408,463	$	19	$	(5,843	)	$	—	$	402,639
U.S. corporate bonds		498,829		3		(4,815	)		—		494,017
International corporate bonds		167,534		—		(2,138	)		—		165,396
U.S. commercial paper		74,170		—		(133	)		—		74,037
International commercial paper		114,107		—		(253	)		—		113,854
U.S. certificates of deposit		19,981		—		—			—		19,981
U.S. municipal securities		37,985		—		(712	)		—		37,273
	$	1,321,069	$	22	$	(13,894	)	$	—	$	1,307,197

	December 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Assets:
U.S. government securities	$	325,514	$	—	$	(982	)	$	—	$	324,532
U.S. corporate bonds		628,836		27		(1,083	)		—		627,780
International corporate bonds		237,303		—		(491	)		—		236,812
U.S. commercial paper		80,194		—		(18	)		—		80,176
International commercial paper		142,358		—		(23	)		—		142,335
U.S. municipal securities		36,518		—		(90	)		—		36,428
	$	1,450,723	$	27	$	(2,687	)	$	—	$	1,448,063

The following tables summarize the fair value and the unrealized losses of the Company’s marketable securities that are in a loss position as of June 30, 2022 and December 31, 2021:

	June 30, 2022
	Less than 12 months					Greater than 12 months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. government securities	$	400,161	$	(5,843	)	$	—	$	—		$	400,161	$	(5,843	)
U.S. corporate bonds		449,691		(4,471	)		27,924		(344	)		477,615		(4,815	)
International corporate bonds		145,479		(1,940	)		21,960		(198	)		167,439		(2,138	)
U.S. commercial paper		30,689		(133	)		—		—			30,689		(133	)
International commercial paper		36,487		(253	)		—		—			36,487		(253	)
U.S. certificates of deposit		—		—			—		—			—		—
U.S. municipal securities		34,273		(712	)		—		—			34,273		(712	)
	$	1,096,780	$	(13,352	)	$	49,884	$	(542	)	$	1,146,664	$	(13,894	)

	December 31, 2021
	Less than 12 months					Greater than 12 months				Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. government securities	$	309,588	$	(982	)	$	—	$	—	$	309,588	$	(982	)
U.S. corporate bonds		601,475		(1,083	)		—		—		601,475		(1,083	)
International corporate bonds		231,672		(491	)		—		—		231,672		(491	)
U.S. commercial paper		21,968		(18	)		—		—		21,968		(18	)
International commercial paper		35,059		(23	)		—		—		35,059		(23	)
U.S. municipal securities		24,953		(90	)		—		—		24,953		(90	)
	$	1,224,715	$	(2,687	)	$	—	$	—	$	1,224,715	$	(2,687	)

As of June 30, 2022 and December 31, 2021, 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 and the contractual cash flows of those investments are guaranteed by the issuer. 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 more likely than not that the Company will be required to sell the investments before recovery of their amortized cost basis.

As of June 30, 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 $186.5 million and maturities of one to two years.

As of December 31, 2021, 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 $436.1 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, 2022 and the year ended December 31, 2021.