
	As of December 31,
	2025		2024
Current marketable investment securities:
Equity securities	$	5,555	$	3,555
Debt securities - AFS	171,631		169,866
Debt securities - HTM(1)	5,590		—
Total current marketable investment securities	$	182,776	$	173,421

The portion of unrealized gains related to equity securities still held during the period is as follows (in thousands):


	Years Ended December 31,
	2025		2024		2023
Net gains on equity securities	$	1,466	$	555	$	—
Less: Net gain recognized on equity securities sold	484		—		—
Net unrealized gains recognized on equity securities still held	$	982	$	555	$	—


	December 31, 2025
	Amortized Cost		Unrealized				Estimated Fair Value
			Gains		Losses
U.S. government securities - AFS	$	171,364	$	269	$	(2)	$	171,631
U.S. government securities - HTM	5,590		11		—		5,601
Total debt securities	$	176,954	$	280	$	(2)	$	177,232


	December 31, 2024
	Amortized Cost		Unrealized				Estimated Fair Value
			Gains		Losses
U.S. government securities - AFS	$	169,636	$	244	$	(14)	$	169,866
U.S. government securities - HTM(1)	—		—		—		—
Total debt securities	$	169,636	$	244	$	(14)	$	169,866

Our U.S. government securities includes both AFS and HTM securities. The AFS securities are available to be sold to meet operating needs or otherwise, but are generally held through maturity. We classify all AFS investments as current assets, as these are readily available for use in current operations. As of December 31, 2025 and 2024, all of our AFS securities had contractual maturities of one year or less.

We classify our HTM investments as current assets, as we have the positive intent and ability to hold these investments to maturity, and all such maturities are less than one year from the balance sheet date.

We evaluated our U.S. government securities under the AFS and HTM impairment model guidance, respectively, and determined our investment portfolio is comprised of low-risk, investment grade securities.

For the years ended December 31, 2025, 2024 and 2023, the unrealized losses on our AFS and HTM U.S. government securities are not attributed to credit risk. We believe that an allowance for credit losses is unnecessary because the unrealized losses on certain of our marketable investment securities are due to market factors. The allowance for credit losses was zero as of December 31, 2025 and 2024.

There were no realized gains or losses on sales of debt securities for the years ended December 31, 2025, 2024 and 2023. In addition, there were no credit-related or noncredit-related impairment losses recognized for the years ended December 31, 2025, 2024 and 2023.

Accrued interest receivable for our AFS and HTM U.S. government securities is included in prepaid expenses and other current assets in the consolidated balance sheets. As of December 31, 2025 and 2024, the accrued interest receivable related to AFS securities was $1.1 million and $0.6 million, respectively. As of December 31, 2025, the accrued interest receivable related to HTM securities was immaterial. There were no amounts accrued as of December 31, 2024, as no securities were classified as HTM at that time.

Additional information relating to the fair value of marketable investment securities can be found in Note 11.