We have investments in certain debt and equity securities, which we record at fair value and primarily include in Other assets in the Consolidated Statement of Financial Position.

We classify debt securities primarily as available-for-sale. We include the unrealized gains and losses arising from the revaluation of available-for-sale debt securities, net of applicable deferred income taxes, in equity (AOCI in the Consolidated Statement of Financial Position). We include the unrealized gains and losses arising from the revaluation of the equity securities in Other income (expense) in the Consolidated Statement of Results of Operations. We generally determine realized gains and losses on sales of investments using the specific identification method for available-for-sale debt and equity securities and include them in Other income (expense) in the Consolidated Statement of Results of Operations.

The cost basis and fair value of available-for-sale debt securities with unrealized gains and losses included in equity (AOCI in the Consolidated Statement of Financial Position) were as follows:


Available-for-sale debt securities	September 30, 2023						December 31, 2022
(Millions of dollars)	Cost Basis		Unrealized Pretax Net Gains (Losses)		Fair Value		Cost Basis		Unrealized Pretax Net Gains (Losses)		Fair Value
Government debt securities
U.S. treasury bonds	$	9	$	—	$	9	$	9	$	—	$	9
Other U.S. and non-U.S. government bonds	57		(4)		53		60		(5)		55

Corporate debt securities
Corporate bonds and other debt securities	2,823		(93)		2,730		2,561		(95)		2,466
Asset-backed securities	193		(4)		189		187		(5)		182

Mortgage-backed debt securities
U.S. governmental agency	429		(45)		384		364		(31)		333
Residential	3		(1)		2		3		(1)		2
Commercial	137		(11)		126		127		(10)		117
Total available-for-sale debt securities	$	3,651	$	(158)	$	3,493	$	3,311	$	(147)	$	3,164


Available-for-sale debt securities in an unrealized loss position:

	September 30, 2023
	Less than 12 months 1				12 months or more 1				Total
(Millions of dollars)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Government debt securities
Other U.S. and non-U.S. government bonds	$	19	$	—	$	25	$	4	$	44	$	4


Corporate debt securities
Corporate bonds	1,660		29		972		64		2,632		93
Asset-backed securities	35		—		88		4		123		4

Mortgage-backed debt securities
U.S. governmental agency	102		4		281		41		383		45
Residential	—		—		2		1		2		1
Commercial	18		1		108		10		126		11
Total	$	1,834	$	34	$	1,476	$	124	$	3,310	$	158


	December 31, 2022
	Less than 12 months 1				12 months or more 1				Total
(Millions of dollars)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Government debt securities

Other U.S. and non-U.S. government bonds	$	19	$	1	$	20	$	4	$	39	$	5
Corporate debt securities
Corporate bonds	1,815		46		357		50		2,172		96
Asset-backed securities	75		2		55		3		130		5

Mortgage-backed debt securities
U.S. governmental agency	229		16		98		15		327		31
Residential	2		—		1		1		3		1
Commercial	63		5		54		5		117		10
Total	$	2,203	$	70	$	585	$	78	$	2,788	$	148

1 Indicates the length of time that individual securities have been in a continuous unrealized loss position.

The unrealized losses on our investments in government debt securities, corporate debt securities, and mortgage-backed debt securities relate to changes in underlying interest rates and credit spreads since time of purchase. We do not intend to sell the investments, and it is not likely that we will be required to sell the investments before recovery of their respective amortized cost basis. In addition, we did not expect credit-related losses on these investments as of September 30, 2023.

The cost basis and fair value of available-for-sale debt securities at September 30, 2023, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to prepay and creditors may have the right to call obligations.


	September 30, 2023
(Millions of dollars)	Cost Basis		Fair Value
Due in one year or less	$	940	$	929
Due after one year through five years	1,812		1,737
Due after five years through ten years	262		248
Due after ten years	68		67
U.S. governmental agency mortgage-backed securities	429		384
Residential mortgage-backed securities	3		2
Commercial mortgage-backed securities	137		126
Total debt securities – available-for-sale	$	3,651	$	3,493


Sales of available-for-sale debt securities:
	Three Months Ended September 30,				Nine Months Ended September 30,
(Millions of dollars)	2023		2022		2023		2022
Proceeds from the sale of available-for-sale securities	$	271	$	204	$	710	$	474
Gross gains from the sale of available-for-sale securities	—		—		—		1
Gross losses from the sale of available-for-sale securities	1		—		1		1

In addition, we had $2,550 million of investments in time deposits classified as held-to-maturity debt securities as of September 30, 2023. We did not have any investments classified as held-to-maturity debt securities as of December 31, 2022. All these investments mature within one year and we include them in Prepaid expenses and other current assets in the Consolidated Statement of Financial Position. We record held-to-maturity debt securities at amortized cost, which approximates fair value.

For the three months ended September 30, 2023 and 2022, the net unrealized gains (losses) for equity securities held at September 30, 2023 and 2022 were $(11) million and $(12) million, respectively. For the nine months ended September 30, 2023 and 2022, the net unrealized gains (losses) for equity securities held at September 30, 2023 and 2022 were $(25) million and $(97) million, respectively.