
	September 30, 2023								December 31, 2022
(in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury securities	$	430	$	—	$	(3)	$	428	$	415	$	—	$	(5)	$	410
U.S. government agencies securities	153		—		(1)		152		36		—		—		35
Non-U.S. government securities	10		—		—		10		34		—		—		34
Certificates of deposit	97		—		—		97		54		—		—		54
Corporate debt securities	1,351		—		(17)		1,334		1,452		—		(26)		1,427
Residential mortgage and asset-backed securities	362		—		(1)		361		335		—		(3)		333
Total	$	2,403	$	—	$	(21)	$	2,382	$	2,325	$	1	$	(34)	$	2,293

The following table summarizes information related to available-for-sale debt securities that have been in a continuous unrealized loss position, classified by length of time:


	September 30, 2023
	Less Than 12 Months				12 Months or Longer				Total
(in millions)	Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury securities	$	(1)	$	261	$	(1)	$	71	$	(3)	$	332
U.S. government agencies securities	(1)		150		—		2		(1)		152
Non-U.S. government securities	—		5		—		5		—		10
Corporate debt securities	(4)		549		(13)		642		(17)		1,191
Residential mortgage and asset-backed securities	(1)		273		—		42		(1)		315
Total	$	(7)	$	1,238	$	(14)	$	761	$	(21)	$	2,000


	December 31, 2022
	Less Than 12 Months				12 Months or Longer				Total
(in millions)	Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury securities	$	(2)	$	174	$	(3)	$	206	$	(5)	$	379
U.S. government agencies securities	—		21		—		—		—		21
Non-U.S. government securities	—		31		—		3		—		34
Corporate debt securities	(17)		774		(8)		439		(26)		1,213
Residential mortgage and asset-backed securities	(2)		205		(1)		56		(3)		261
Total	$	(22)	$	1,204	$	(12)	$	705	$	(34)	$	1,908

No allowance for credit losses was recognized for investments with unrealized losses as of September 30, 2023, as the unrealized losses were primarily driven by broader change in interest rates with no adverse conditions identified that would prevent the issuer from making scheduled principal and interest payments. We do not currently intend to sell, and it is not more likely than not that we will be required to sell, such investments before recovery of their amortized cost bases.

The following table summarizes the classification of our available-for-sale debt securities in our Condensed Consolidated Balance Sheets:


(in millions)	September 30, 2023		December 31, 2022
Cash and cash equivalents	$	67	$	75
Short-term marketable debt securities	1,159		973
Long-term marketable debt securities	1,156		1,245
Total	$	2,382	$	2,293


	September 30, 2023
(in millions)	Amortized Cost		Fair Value
Within one year	$	1,233	$	1,226
After one year through five years	1,161		1,147
After five years through ten years	6		6
After ten years	3		3
Total	$	2,403	$	2,382

The following table summarizes the classification of our equity securities measured at fair value on a recurring basis, on our Condensed Consolidated Balance Sheets:


(in millions)	September 30, 2023		December 31, 2022
Cash and cash equivalents	$	4,240	$	3,831
Prepaid and other current assets(1)	1,110		473
Other long-term assets(1)	244		943
Total	$	5,594	$	5,248

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(1) Includes our equity method investments in Arcus and Galapagos, for which we elected and applied the fair value option as we believe it best reflects the underlying economics of these investments. Our investment in Arcus was classified in Prepaid and other current assets as of September 30, 2023 and December 31, 2022. Our investment in Galapagos is subject to certain lock-up provisions until August 2024 and was classified in Prepaid and other current assets and in Other long-term assets as of September 30, 2023 and December 31, 2022, respectively.

Equity method investments and other equity investments without readily determinable fair values were $337 million and $423 million as of September 30, 2023 and December 31, 2022, respectively, and were excluded from the table above. These amounts were included in Other long-term assets on our Condensed Consolidated Balance Sheets.

We recognized $168 million and $356 million net unrealized losses on equity securities for the three and nine months ended September 30, 2023, respectively, and $197 million and $596 million net unrealized losses on equity securities for the three and nine months ended September 30, 2022, respectively, which were included in Other income (expense), net on our Condensed Consolidated Statements of Income.

During the nine months ended September 30, 2022, Gilead donated certain equity securities at fair value to the Gilead Foundation, a California nonprofit public benefit corporation (the “Foundation”). The Foundation is a related party as certain of our officers also serve as directors of the Foundation. The donation expense of $85 million was recorded within Selling, general and administrative expenses on our Condensed Consolidated Statements of Income during the nine months ended September 30, 2022.