The following tables present amortized cost and fair values of investments at June 30, 2023 and December 31, 2022, respectively:


June 30, 2023	Amortized cost		Accumulated unrealized gains		Accumulated unrealized losses		Fair value
	(in thousands)
Investment securities, held-to-maturity
U.S. government and government agencies and authorities	$	7,665	$	—	$	(365)	$	7,300
Investment securities, available-for-sale
U.S. government and government agencies and authorities	178,186		—		(5,993)		172,193
Corporate debt securities	93,636		11		(733)		92,914

Total held-to-maturity and available-for-sale investment securities	$	279,487	$	11	$	(7,091)	$	272,407


December 31, 2022	Amortized cost		Accumulated unrealized gains		Accumulated unrealized losses		Fair value
	(in thousands)
Investment securities, held-to-maturity
U.S. government and government agencies and authorities	$	757	$	—	$	(106)	$	651
Investment securities, available-for-sale
U.S. government and government agencies and authorities	237,457		10		(9,000)		228,467
Corporate debt	98,783		38		(422)		98,399

Total held-to-maturity and available-for-sale investment securities	$	336,997	$	48	$	(9,528)	$	327,517

The following table presents the amortized cost and fair value of debt securities at June 30, 2023, by contractual maturity:


June 30, 2023	Held-to-maturity				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
	(in thousands)
Due within one year	$	3,680	$	3,511	$	184,424	$	182,600
Due after one year through five years	3,875		3,694		87,398		82,507
Due after five years through ten years	—		—		—		—
Due after ten years	110		95		—		—
Total	$	7,665	$	7,300	$	271,822	$	265,107

For the three and six months ended June 30, 2023 and 2022, respectively, net investment income, which is included within Other income within the Condensed Consolidated Statements of Operations and Comprehensive Loss, was derived from the following sources:


	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
	(in thousands)				(in thousands)
Cash and cash equivalents	$	2,405	$	136	$	4,034	$	138
Short-term investments	823		50		1,315		121
Investment securities	1,668		277		3,482		514
Investment income, net	$	4,896	$	463	$	8,831	$	773

Gross unrealized losses and fair values aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position were as follows at June 30, 2023, and December 31, 2022, respectively:


June 30, 2023	Less than 12 months				Greater than 12 months				Total
	Fair value		Unrealized loss		Fair value		Unrealized loss		Fair value		Unrealized loss
	(in thousands, except number of positions)
U.S. government and government agencies and authorities	$	21,726	$	(187)	$	155,695	$	(6,170)	$	177,421	$	(6,357)
Corporate debt securities	86,128		(721)		—		(13)		86,128		(734)
Total	$	107,854	$	(908)	$	155,695	$	(6,183)	$	263,549	$	(7,091)
Number of positions	94				29				123


December 31, 2022	Less than 12 months				Greater than 12 months				Total
	Fair value		Unrealized loss		Fair value		Unrealized loss		Fair value		Unrealized loss
	(in thousands, except number of positions)
U.S. government and government agencies and authorities	$	64,261	$	(958)	$	147,757	$	(8,148)	$	212,018	$	(9,106)
Corporate debt securities	78,292		(422)		—		—		78,292		(422)
Total	$	142,553	$	(1,380)	$	147,757	$	(8,148)	$	290,310	$	(9,528)
Number of positions	92				24				116

The Company did not record any credit allowances for debt securities that were in an unrealized loss position at June 30, 2023 and December 31, 2022.

At June 30, 2023, all securities were investment grade, with credit ratings of BBB+ or higher by S&P Global or as determined by other credit rating agencies within the Company's investment policy. Unrealized losses on investment grade securities are principally related to changes in interest rates or changes in issuer or sector related credit spreads since the securities were acquired. The gross unrealized investment losses at June 30, 2023, were assessed, based on, among other things:

•The relative magnitude to which fair values of these securities have been below their amortized cost was not indicative of an impairment loss;

•The absence of compelling evidence that would cause the Company to call into question the financial condition or near-term prospects of the issuer of the applicable security; and

•The Company's ability and intent to hold the applicable security for a period of time sufficient to allow for any anticipated recovery.

Proceeds from sales and maturities of investment securities, inclusive of Short-term investments, and related gross realized gains (losses) which are included within Other income within the Condensed Consolidated Statements of Operations and Comprehensive Loss, were as follows for the three and six months ended June 30, 2023 and 2022, respectively:


	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
	(in thousands)				(in thousands)
Proceeds from sales of investment securities	$	45,435	$	5,881	$	60,436	$	5,881
Proceeds from maturities of investment securities	27,673		140,455		90,997		290,455

Gross realized gains	38		5		38		5
Gross realized losses	(19)		(21)		(19)		(21)
Net realized losses	$	19	$	(16)	$	19	$	(16)

At June 30, 2023 and December 31, 2022, the Company had $14.5 million and $14.3 million, respectively, in deposits with various states and regulatory bodies that are included as part of the Company's investment balances.