The Company’s equity and debt securities consisted of the following:


	March 31, 2023
	Amortized Cost Basis			Unrealized Gains		Unrealized Losses			Aggregate Fair Value
	(in thousands)
Equity securities:
Long-term
Preferred stock of privately held company	$	15,000		$	—	$	—		$	15,000
Total equity securities		15,000			—		—			15,000
Available-for-sale debt securities
Short-term
U.S. government debt securities		176,704			—		(3,233	)		173,471
Corporate debt securities		119,175			—		(2,383	)		116,792
U.S. agency debt securities		87,707			67		(476	)		87,298
U.S. treasury bills		67,944			1		(62	)		67,883
Money market accounts		11,902			—		—			11,902
Municipal bonds		7,885			—		(72	)		7,813
Less: Cash equivalents		(26,846	)		—		—			(26,846	)
Total debt securities due within 1 year		444,471			68		(6,226	)		438,313
After 1 year through 5 years
U.S. government debt securities		185,378			725		(3,838	)		182,265
U.S. agency debt securities		123,823			229		(2,456	)		121,596
Corporate debt securities		51,058			—		(2,717	)		48,341
Municipal bonds		10,553			2		(121	)		10,434
Yankee debt securities		753			—		(81	)		672
Redeemable preferred stock investment		20,000			—		(7,018	)		12,982
Total debt securities due after 1 year through 5 years		391,565			956		(16,231	)		376,290
After 5 years through 10 years
Municipal bonds		3,580			—		(55	)		3,525
Total debt securities due after 5 years through 10 years		3,580			—		(55	)		3,525
Total available-for-sale debt securities		839,616			1,024		(22,512	)		818,128
Total equity and debt securities	$	854,616		$	1,024	$	(22,512	)	$	833,128


	December 31, 2022
	Amortized Cost Basis			Unrealized Gains		Unrealized Losses			Aggregate Fair Value
	(in thousands)
Equity securities:
Long-term
Preferred stock of privately held company	$	15,000		$	—	$	—		$	15,000
Total equity securities		15,000			—		—			15,000
Available-for-sale debt securities
Short-term
U.S. government debt securities		189,333			—		(3,373	)		185,960
Corporate debt securities		120,480			—		(2,222	)		118,258
U.S. treasury bills		69,991			—		(193	)		69,798
U.S. agency debt securities		68,411			—		(342	)		68,069
Money market accounts		27,455			—		—			27,455
Municipal bonds		7,371			—		(80	)		7,291
Yankee debt securities		2,347			—		(5	)		2,342
Less: Cash equivalents		(32,444	)		—		—			(32,444	)
Total debt securities due within 1 year		452,944			—		(6,215	)		446,729
After 1 year through 5 years
U.S. government debt securities		152,435			2		(6,349	)		146,088
U.S. agency debt securities		92,054			—		(3,435	)		88,619
Corporate debt securities		80,647			—		(4,756	)		75,891
Municipal bonds		12,065			—		(217	)		11,848
Yankee debt securities		753			—		(85	)		668
Redeemable preferred stock investment		20,000			—		(7,615	)		12,385
Total debt securities due after 1 year through 5 years		357,954			2		(22,457	)		335,499
After 5 years through 10 years
Municipal bonds		3,617			—		(83	)		3,534
Total debt securities due after 5 years through 10 years		3,617			—		(83	)		3,534
Total available-for-sale debt securities		814,515			2		(28,755	)		785,762
Total equity and debt securities	$	829,515		$	2	$	(28,755	)	$	800,762

Gross unrealized losses on the Company’s equity and debt securities were $22.5 million and $28.8 million as of March 31, 2023 and December 31, 2022, respectively. The Company did not recognize any credit losses for its available-for-sale debt securities during the first quarters of 2023 and 2022.

The Company’s marketable securities of $478.0 million, managed by the custodian of the Company’s marketable debt security investment account, of which the Company has an outstanding margin loan, is used as collateral for the margin account borrowing. See Note 8, Debt, Commitments and Contingencies, for more information on the margin loan.