Marketable Securities

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

The Company’s marketable securities, which consist of highly liquid marketable debt securities, are classified as available-for-sale and are stated at fair value. The following tables summarize the Company’s marketable securities (in thousands):


As of September 30, 2023	Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury securities	1 or less	$	318,419	$	1	$	(1,142)	$	317,278
U.S. Government agency securities	1 or less	5,000		—		(10)		4,990
Negotiable certificates of deposit	1 or less	5,880		—		(21)		5,859
Corporate debt securities	1 or less	1,256		—		(11)		1,245
U.S. Treasury securities	1 - 2	126,786		—		(679)		126,107
Negotiable certificates of deposit	1 - 2	1,470		—		(16)		1,454

Total		$	458,811	$	1	$	(1,879)	$	456,933


As of December 31, 2022	Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury securities	1 or less	$	230,349	$	1	$	(2,283)	$	228,067
U.S. Government agency securities	1 or less	5,000		—		(34)		4,966
Negotiable certificates of deposit	1 or less	3,911		1		(57)		3,855
Corporate debt securities	1 or less	16,360		—		(286)		16,074
U.S. Treasury securities	1 - 2	16,919		—		(41)		16,878
Negotiable certificates of deposit	1 - 2	490		1		—		491
Total		$	273,029	$	3	$	(2,701)	$	270,331

The unrealized losses on the Company’s marketable securities of $1.9 million as of September 30, 2023, $0.2 million of which were in a continuous unrealized loss position of greater than 12 months, were caused by interest rate increases which resulted in the decrease in market value of these securities. Because the decline in fair value is attributable to changes in interest rates and not credit quality, and because the Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be maturity, there were no allowances for credit losses at September 30, 2023 and December 31, 2022.

Accrued interest receivable on available-for-sale securities was $2.3 million and $1.3 million at September 30, 2023 and December 31, 2022, respectively. We have not written off any accrued interest receivable for the three or nine months ended September 30, 2023 and 2022.