Investments

6 Months Ended

Jun. 30, 2022

4. Investments

The fair value of available-for-sale investments by type of security was as follows:


	June 30, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Investments:
U.S. treasury bills	$	332,729	$	—	$	(4,150	)	$	328,579
U.S. agency securities		165,061		—		(1,462	)		163,599
Total investments with a maturity of one year or less		497,790		—		(5,612	)		492,178

U.S. treasury bills		154,076		—		(3,775	)		150,301
U.S. agency securities		90,294		—		(2,519	)		87,775
Total investments with a maturity of one to two years		244,370		—		(6,294	)		238,076
Total investments	$	742,160	$	—	$	(11,906	)	$	730,254


	December 31, 2021
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Investments:
U.S. treasury bills	$	189,406	$	—	$	(228	)	$	189,178
U.S. agency securities		108,895		—		(138	)		108,757
Total investments with a maturity of one year or less		298,301		—		(366	)		297,935

U.S. treasury bills		280,743		—		(535	)		280,208
U.S. agency securities		99,998		—		(187	)		99,811
Total investments with a maturity of one to two years		380,741		—		(722	)		380,019
Total investments	$	679,042	$	—	$	(1,088	)	$	677,954

Pursuant to the Company’s adoption of ASU 2016-13 and the related amendments thereto on January 1, 2022, the Company reviews investments whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. In connection therewith, the Company evaluates whether the decline in fair value has resulted from credit losses or other factors, considering the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security is compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded for the credit loss on the condensed consolidated balance sheet, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that is not related to credit is recognized in other comprehensive (loss) income. Changes in the allowance for credit losses are recorded as a provision for (or reversal of) credit loss expense in general and administrative expenses within the condensed consolidated statement of operations. Losses are charged against the allowance when the Company believes the uncollectability of an available-for-sale security is confirmed or when either of the criteria regarding intent or requirement to sell is met.

The Company held 112 and 88 debt securities that were in an unrealized loss position as of June 30, 2022 and December 31, 2021, respectively. The unrealized losses at June 30, 2022 and December 31, 2021 were attributable to changes in interest rates and the unrealized losses do not represent credit losses. The Company does not intend to sell these securities and it is not more likely than not that it will be required to sell them before recovery of their amortized cost basis.

The following table summarizes our available-for-sale debt securities in an unrealized loss position for which an allowance for credit losses has not been recorded at June 30, 2022, aggregated by major security type and length of time in a continuous unrealized loss position (in thousands):


	Less than 12 Months					12 Months or Longer				Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses

U.S. treasury bills	$	478,880	$	(7,925	)	$	—	$	—	$	478,880	$	(7,925	)
U.S. agency securities		251,374		(3,981	)		—		—		251,374		(3,981	)
Total	$	730,254	$	(11,906	)	$	—	$	—	$	730,254	$	(11,906	)

The following table summarizes our available-for-sale debt securities in an unrealized loss position for which an allowance for credit losses has not been recorded at December 31, 2021, aggregated by major security type and length of time in a continuous unrealized loss position (in thousands):


	Less than 12 Months					12 Months or Longer				Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses

U.S. treasury bills	$	469,386	$	(763	)	$	—	$	—	$	469,386	$	(763	)
U.S. agency securities		208,568		(325	)		—		—		208,568		(325	)
Total	$	677,954	$	(1,088	)	$	—	$	—	$	677,954	$	(1,088	)