Marketable Securities

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

The amortized cost, gross unrealized holding gains, gross unrealized holding losses and fair value of debt securities available-for-sale by type of security at September 30, 2023 and December 31, 2022 were as follows:


	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
September 30, 2023
Debt securities
U.S. corporate bonds	$	64,635	$	—	$	64,635	$	—	$	(62)	$	64,573
Foreign corporate bonds	24,623		—		24,623		—		(19)		24,604

U.S. treasury bills	39,759		—		39,759		3		—		39,762
U.S. agency bonds	4,965		—		4,965		—		(5)		4,960
Total	$	133,982	$	—	$	133,982	$	3	$	(86)	$	133,899

December 31, 2022
Debt securities
U.S. corporate bonds	$	142,697	$	—	$	142,697	$	25	$	(135)	$	142,587
Foreign corporate bonds	36,766		—		36,766		9		(32)		36,743

U.S. treasury bills	89,308		—		89,308		17		(5)		89,320
U.S. agency bonds	41,734		—		41,734		—		(24)		41,710
Total	$	310,505	$	—	$	310,505	$	51	$	(196)	$	310,360

The fair value of debt securities available-for-sale by classification in the condensed consolidated balance sheets was as follows:


	September 30, 2023		December 31, 2022
Cash and cash equivalents	$	5,000	$	49,896
Marketable securities	128,899		260,464
Total	$	133,899	$	310,360

The net amortized cost and fair value of debt securities available-for-sale at September 30, 2023 and December 31, 2022 are shown below by contractual maturity. Actual maturities may differ from contractual maturities because securities may be restructured, called or prepaid, or the Company intends to sell a security prior to maturity.


	September 30, 2023				December 31, 2022
	Net Amortized Cost		Fair Value		Net Amortized Cost		Fair Value
Due to mature:
Less than one year	$	133,982	$	133,899	$	310,505	$	310,360

Summarized below are the debt securities available-for-sale the Company held at September 30, 2023 and December 31, 2022 that were in an unrealized loss position, aggregated by the length of time the investments have been in that position:


	Less than 12 months
	Number of Securities	Fair Value		Unrealized Losses
September 30, 2023
Debt securities
U.S. corporate bonds	11	$	64,573	$	(62)
Foreign corporate bonds	3	24,604		(19)
U.S. treasury bills	2	9,882		—
U.S. agency bonds	1	4,960		(5)
Total	17	$	104,019	$	(86)

December 31, 2022
Debt securities
U.S. corporate bonds	16	$	104,508	$	(135)
Foreign corporate bonds	3	31,886		(32)

U.S. treasury bills	1	9,762		(5)
U.S. agency bonds	4	41,710		(24)
Total	24	$	187,866	$	(196)

The Company did not have any investments in a continuous unrealized loss position for more than twelve months as of September 30, 2023 and December 31, 2022.

The Company reviewed the securities in the table above and concluded that they are performing assets, considering factors such as the credit quality of the investment security based on research performed by external rating agencies and the prospects of realizing the carrying value of the security based on the investment’s current prospects for recovery. As of September 30, 2023, the Company did not intend to sell these securities and did not believe it was more likely than not that it would be required to sell these securities prior to the anticipated recovery of their amortized cost basis.

Net Investment Income

Gross investment income includes income from debt securities available-for-sale, money-market funds, cash and restricted cash. Sources of net investment income included in other income (expense), net in the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2023 were as follows:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2023		2023
Gross investment income	$	3,831	$	12,231
Investment expenses	(65)		(203)
Net investment income (excluding net realized capital losses)	3,766		12,028
Net realized capital losses	—		(39)
Net investment income	$	3,766	$	11,989

The Company had no investment income during the three and nine months ended September 30, 2022.

We utilize the specific identification method in computing realized gains and losses. The proceeds from the sale of available-for-sale debt securities and the related gross realized capital losses for the three and nine months ended September 30, 2023 were as follows:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2023		2023
Proceeds from sales	$	—	$	4,920

Gross realized capital losses	—		$	39

The Company had no proceeds from the sale of available-for-sale debt securities and the related gross realized capital gains and losses for the three and nine months ended September 30, 2022.