Investment securities classified as available-for-sale consisted of the following as of December 31, 2024 and 2023 (in thousands):


	December 31, 2024
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value


U.S. government and agency securities	$	235,509	$	261	$	(25)	$	235,745
Total available-for-sale investment securities	$	235,509	$	261	$	(25)	$	235,745


	December 31, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value


U.S. government and agency securities	162,062		193		(59)		162,196
Total available-for-sale investment securities	$	162,062	$	193	$	(59)	$	162,196

As of December 31, 2024, the decline in fair value below amortized cost basis was not considered other than temporary as it is more likely than not we will hold the securities until maturity or recovery of the cost basis. No allowance for credit losses for available-for-sale investment securities was recorded as of December 31, 2024 or 2023.

The fair values of available-for-sale investment securities, by remaining contractual maturity, are as follows (in thousands):


	December 31, 2024				December 31, 2023
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Due in one year or less	$	235,509	$	235,745	$	162,062	$	162,196

Total available-for-sale investment securities	$	235,509	$	235,745	$	162,062	$	162,196

During the years ended December 31, 2024 and 2023, we had sales and maturities (which include calls) of investment securities, as follows (in thousands):


	Year Ended December 31, 2024
	Gross Realized Gains		Gross Realized Losses		Gross Proceeds from Sales		Gross Proceeds from Maturities
U.S. government and agency securities	4		(1)		9,984		240,035
	$	4	$	(1)	$	9,984	$	240,035


	Year Ended December 31, 2023
	Gross Realized Gains		Gross Realized Losses		Gross Proceeds from Sales		Gross Proceeds from Maturities
Corporate bonds	$	3	$	—	$	1,013	$	16,497
U.S. government and agency securities	—		—		—		135,885
	$	3	$	—	$	1,013	$	152,382

The tables above do not include our non-marketable equity securities of $2.0 million, which are recorded in Other long term assets in the Consolidated Balance Sheet as of December 31, 2024.

The following tables present our financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2024 and 2023 by level within the fair value hierarchy (in thousands):


	December 31, 2024
	Level 1		Level 2		Total Fair Value
Cash equivalents:
Money market funds	$	25,167	$	—	$	25,167

Available-for-sale investment securities:



U.S. government and agency securities	—		235,745		235,745
Total	$	25,167	$	235,745	$	260,912


	December 31, 2023
	Level 1		Level 2		Total Fair Value
Cash equivalents:
Money market funds	$	37,100	$	—	$	37,100

Available-for-sale investment securities:

U.S. government and agency securities	—		162,196		162,196


Total	$	37,100	$	162,196	$	199,296

The carrying amounts of cash and cash equivalents, restricted cash, accounts receivable, accounts payable and accrued liabilities approximate their fair value because of the short maturity of these items.

There were no changes to our valuation techniques used to measure asset and liability fair values on a recurring basis during the year ended December 31, 2024. The valuation techniques for the financial assets in the tables above are as follows:

As of December 31, 2024 and 2023, cash equivalents include cash invested in money market funds with a maturity of three months or less. Fair value is based on market prices for identical assets.

Fair value for our Level 1 investment securities is based on market prices for identical assets. Our Level 2 securities were priced by a pricing vendor. The pricing vendor utilizes the most recent observable market information in pricing these securities or, if specific prices are not available for these securities, other observable inputs like market transactions involving comparable securities are used.