The following table summarizes the Company’s marketable securities held at December 31, 2023 (in thousands):


	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial paper	$	285,054	$	250	$	(15	)	$	285,289
Corporate notes		23,462		63		—			23,525
U.S. Treasury securities		151,805		436		(94	)		152,147
U.S. Government securities		271,181		328		(364	)		271,145
Corporate equity securities		21,875		—		—			21,875
Total	$	753,377	$	1,077	$	(473	)	$	753,981

The following table summarizes the Company’s marketable securities held at December 31, 2022 (in thousands):


	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial paper	$	578,813	$	72	$	(1,157	)	$	577,728
Corporate notes		19,033		—		(37	)		18,996
U.S. Treasury securities		146,270		—		(958	)		145,312
U.S. Government securities		63,214		13		(363	)		62,864
Corporate equity securities		40,467		—		—			40,467
Total	$	847,797	$	85	$	(2,515	)	$	845,367

The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity. At December 31, 2023 and 2022, the balance in accumulated other comprehensive (loss) income was comprised solely of activity related to marketable securities. There were no realized gains or losses recognized on the sale or maturity of marketable securities for the years ended December 31, 2023, 2022 and 2021 and, as a result, the Company did not reclassify any amounts out of accumulated other comprehensive (loss) income for the same periods.

The Company holds debt securities of companies with high credit quality and has determined that there was no material change in the credit risk of any of its debt securities. The contractual maturity dates of all the investments are less than one year.