SHORT-TERM INVESTMENTS

3 Months Ended

Mar. 31, 2023

SHORT-TERM INVESTMENTS.

SHORT-TERM INVESTMENTS

6.  SHORT-TERM INVESTMENTS

The following tables summarize the amortized cost, gross unrealized gains, gross unrealized losses and fair value of available-for-sale investments by type of security (in thousands):

	March 31, 2023
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses		Fair Value
Available-for-sale securities:
U.S. treasury bills (due within 1 year)	$	9,904	$	6	$	—	$	9,910
U.S. agency securities (due within 1 year)		207,370		121		—		207,491
Commercial paper (due within 1 year)		728,286		46		(146)		728,186
Corporate notes (due within 1 year)		11,994		3		—		11,997
Total available-for-sale securities	$	957,554	$	176	$	(146)	$	957,584

	December 31, 2022
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses		Fair Value
Available-for-sale securities:
U.S. treasury bills (due within 1 year)	$	63,971	$	—	$	(164)	$	63,807
U.S. agency securities (due within 1 year)		14,733		11		—		14,744
Commercial paper (due within 1 year)		814,772		247		(287)		814,732
Corporate notes (due within 1 year)		11,870		—		(3)		11,867
Total available-for-sale securities	$	905,346	$	258	$	(454)	$	905,150

There were no realized gains or losses on investments for the three months ended March 31, 2023. There were 17 and 12 investments in an unrealized loss position as of March 31, 2023 and December 31, 2022, respectively. None of these investments was in an unrealized loss position for greater than 12 months as of March 31, 2023 or December 31, 2022. The unrealized losses on the Company's available-for-sale securities were caused by the impact of central bank and market interest rates on the investments held. 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 bases. The Company did not record an allowance for credit losses as of March 31, 2023 or December 31, 2022.