Available-for sale securities are classified as short-term versus long-term investments based on whether they represent the investment of funds available for current operations. Currently, all available-for-sale securities are considered short-term in nature. Held-to-maturity securities are classified as short-term versus long-term investments based on their maturity dates. The amortized cost, gross unrealized holding gains and losses, and estimated fair value of long-term and short-term investments by major security type and class of security were as follows as of June 30, 2025 and December 31, 2024 (in thousands):


	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
As of June 30, 2025
Long-term investments:



Held-to-maturity investments
U.S. treasury securities	$	167	$	—	$	—	$	167
	$	167	$	—	$	—	$	167
Short-term investments:
Available-for-sale investments
U.S. treasury securities	$	87,965	$	436	$	(30)	$	88,371
Mortgage-backed securities and collateralized mortgage obligations	19,316		141		(22)		19,435
Other asset-backed securities	21,131		129		(3)		21,257

Corporate bonds	48,802		567		—		49,369
	$	177,214	$	1,273	$	(55)	$	178,432
Held-to-maturity investments
U.S. treasury securities	$	10,547	$	1	$	(9)	$	10,539
Certificates of deposit	7,875		—		—		7,875

	$	18,422	$	1	$	(9)	$	18,414


	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
As of December 31, 2024
Long-term investments:



Held-to-maturity investments
U.S. treasury securities	$	373	$	—	$	(1)	$	372
	$	373	$	—	$	(1)	$	372
Short-term investments:
Available-for-sale investments
U.S. treasury securities	$	70,175	$	318	$	(202)	$	70,291
Mortgage-backed securities and collateralized mortgage obligations	12,576		80		(60)		12,596
Other asset-backed securities	15,830		134		(8)		15,956

Corporate bonds	35,382		284		(43)		35,623
	$	133,963	$	816	$	(313)	$	134,466
Held-to-maturity investments
U.S. treasury securities	$	10,591	$	16	$	(1)	$	10,606
Certificates of deposit	2,032		—		—		2,032

	$	12,623	$	16	$	(1)	$	12,638


	As of June 30, 2025
	Amortized Cost		Fair Value
Available-for-sale:
Due under one year	$	—	$	—
Due after one year through five years	136,767		137,740
Due after five years through ten years	—		—
Due after ten years	—		—
	$	136,767	$	137,740
Available-for-sale collateralized:
Due under one year	$	4,099	$	4,114
Due after one year through five years	26,687		26,879
Due after five years through ten years	9,410		9,437
Due after ten years	251		262
	$	40,447	$	40,692
Held-to-maturity:
Due under one year	$	18,422	$	18,414
Due after one year through five years	167		167
	$	18,589	$	18,581

The following tables present the gross unrealized losses and related fair values for the Company's investment in available-for-sale securities, grouped by duration of time in a continuous unrealized loss position as of June 30, 2025 and December 31, 2024 (in thousands):


	Less than 12 Months				12 Months or More				Total
	Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss
As of June 30, 2025
U.S. Treasury securities	$	19,962	$	(30)	$	—	$	—	$	19,962	$	(30)
Mortgage-backed securities and collateralized mortgage obligations	908		(3)		1,151		(19)		2,059		(22)
Other asset-backed securities	1,918		(1)		1,293		(2)		3,211		(3)
Corporate bonds	—		—		—		—		—		—
Total	$	22,788	$	(34)	$	2,444	$	(21)	$	25,232	$	(55)


	Less than 12 Months				12 Months or More				Total
	Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss
As of December 31, 2024
U.S. Treasury securities	$	27,769	$	(202)	$	—	$	—	$	27,769	$	(202)
Mortgage-backed securities and collateralized mortgage obligations	1,538		(20)		1,359		(40)		2,897		(60)
Other asset-backed securities	186		(1)		1,737		(7)		1,923		(8)
Corporate bonds	6,461		(40)		736		(3)		7,197		(43)
Total	$	35,954	$	(263)	$	3,832	$	(50)	$	39,786	$	(313)

Unrealized losses on available-for-sale investments relate to interest rate changes. The Company does not expect material credit losses from its available-for-sale investments, considering the composition of the investment portfolio and the credit rating of these investments. The Company determined it is not likely to, and does not intend to, sell securities currently in a loss position prior to a potential recovery of their cost basis. The Company does not expect material credit losses from its held-to-maturity investments, considering the composition of the investment portfolio and the credit loss history of these investments.