
	March 31, 2025
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale debt securities:
Commercial paper	$	254	$	—	$	—	$	254
Corporate notes and bonds	5,265		24		(1)		5,288
Certificates of deposit	48		—		—		48
U.S. government and agency securities	1,882		5		(1)		1,886
Mortgage-backed and asset-backed securities	103		—		(16)		87

Total available-for-sale debt securities	$	7,552	$	29	$	(18)	$	7,563


	December 31, 2024
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale debt securities:
Commercial paper	$	336	$	—	$	—	$	336
Corporate notes and bonds	4,966		15		(5)		4,976
Certificates of deposit	67		—		—		67
U.S. government and agency securities	2,103		3		(2)		2,104
Mortgage-backed and asset-backed securities	104		—		(18)		86

Total available-for-sale debt securities	$	7,576	$	18	$	(25)	$	7,569

As of March 31, 2025, the contractual maturities of our available-for-sale debt securities, excluding those securities classified within cash and cash equivalents on the condensed consolidated balance sheet and mortgage-backed and asset-backed securities that do not have a single maturity, did not exceed 37 months. The fair values of available-for-sale debt securities, by remaining contractual maturity, are as follows (in millions):

As of March 31, 2025 and December 31, 2024, unrealized losses of $16 million and $18 million, respectively, are from available-for-sale debt securities in a continuous unrealized loss position greater than 12 months. As of March 31, 2025 and December 31, 2024, the fair value of available-for-sale debt securities in a continuous unrealized loss position totaled $1,329 million and $2,419 million, respectively, the majority of which has been in a continuous unrealized loss position for less than 12 months.

For all available-for-sale debt securities that were in unrealized loss positions, we have determined that it is more likely than not we will hold the securities until maturity or a recovery of the cost basis. Unrealized losses on available-for-sale debt securities were due primarily to changes in market interest rates, and credit-related impairment losses were immaterial as of March 31, 2025.

As of March 31, 2025 and December 31, 2024, the total amount of non-marketable equity investments in privately held companies included in other assets on our condensed consolidated balance sheets was $473 million and $469 million, respectively. Our non-marketable equity investments are primarily accounted for using the measurement alternative, which measures the investments at cost, minus impairment, if any, plus or minus changes resulting from qualifying observable price changes resulting from the issuance of similar or identical securities in an orderly transaction by the same issuer. Determining whether an observed transaction is similar to a security within our portfolio requires judgment based on the rights and preferences of the securities. Recording upward and downward adjustments to the carrying value of our non-marketable equity investments as a result of observable price changes requires quantitative assessments of the fair value of our non-marketable equity investments using various valuation methodologies and involves the use of estimates. The adjustments made during the three months ended March 31, 2025 and 2024 were immaterial. We classify these fair value measurements as Level 3 within the fair value hierarchy.