Short-term Investments

12 Months Ended

Dec. 31, 2023

Short-Term Investments [Abstract]

Short-term Investments

4. Short-term Investments

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

	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Investments:
U.S. treasury bills	$	76,881	$	37	$	—		$	76,918
U.S. Government Agency and foreign national bank securities		3,486		—		(4	)	$	3,482
Total investments	$	80,367	$	37	$	(4	)	$	80,400

	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Investments:
U.S. treasury bills	$	2,966	$	—	$	—		$	2,966
Corporate Bonds and U.S. Government Agency Securities		62,368		14		(4	)		62,378
Total investments	$	65,334	$	14	$	(4	)	$	65,344

The Company held two debt securities that were in an unrealized loss position as of December 31, 2023. The aggregated fair value of debt securities in an unrealized loss position was $3.5 million. As of December 31, 2023, the Company did not hold debt securities in a continuous unrealized loss position for more than 12 months.

The Company held four debt securities that were in an unrealized loss position as of December 31, 2022. The aggregated fair value of debt securities in an unrealized loss position was $3.9 million. As of December 31, 2022, the Company did not hold debt securities in a continuous unrealized loss position for more than 12 months.

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 on the 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 as a separate component of stockholders' equity. 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 consolidated statements of operations and comprehensive loss. 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 unrealized losses at December 31, 2023 are attributable to changes in interest rates.