Investment securities (Tables)

9 Months Ended

Sep. 30, 2024

Investments, Debt and Equity Securities [Abstract]

Amortized Cost and Estimated Fair Value of Investment Securities

The amortized cost and estimated fair value of investment securities were as follows:

(Dollars in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
September 30, 2024
Investment securities available for sale:
U.S. Treasury and federal agencies	$	7,824	$	62	$	26	$	7,860
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	3,125		55		3		3,177
Residential	5,606		60		77		5,589
Other debt securities	103		—		2		101
	16,658		177		108		16,727
Investment securities held to maturity:
U.S. Treasury and federal agencies	1,013		—		14		999
Obligations of states and political subdivisions	2,397		—		71		2,326
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	2,038		—		81		1,957
Residential	9,016		13		646		8,383
Privately issued	38		8		3		43
Other debt securities	1		—		—		1
	14,503		21		815		13,709
Total debt securities	$	31,161	$	198	$	923	$	30,436
Equity and other securities:
Readily marketable equity — at fair value	$	250	$	9	$	2	$	257
Other — at cost	840		—		—		840
Total equity and other securities	$	1,090	$	9	$	2	$	1,097
December 31, 2023
Investment securities available for sale:
U.S. Treasury and federal agencies	$	7,818	$	—	$	113	$	7,705
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	425		—		9		416
Residential	2,272		—		118		2,154
Other debt securities	176		—		11		165
	10,691		—		251		10,440
Investment securities held to maturity:
U.S. Treasury and federal agencies	1,005		—		31		974
Obligations of states and political subdivisions	2,501		—		67		2,434
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	2,033		—		130		1,903
Residential	9,747		4		802		8,949
Privately issued	42		9		5		46
Other debt securities	2		—		—		2
	15,330		13		1,035		14,308
Total debt securities	$	26,021	$	13	$	1,286	$	24,748
Equity and other securities:
Readily marketable equity — at fair value	$	266	$	5	$	3	$	268
Other — at cost	859		—		—		859
Total equity and other securities	$	1,125	$	5	$	3	$	1,127

Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity

At September 30, 2024, the amortized cost and estimated fair value of debt securities by contractual maturity were as follows:

(Dollars in millions)	Amortized Cost		Estimated Fair Value
Debt securities available for sale:
Due in one year or less	$	3,206	$	3,187
Due after one year through five years	4,721		4,774
Due after five years through ten years	—		—
Due after ten years	—		—
	7,927		7,961
Mortgage-backed securities	8,731		8,766
	$	16,658	$	16,727
Debt securities held to maturity:
Due in one year or less	$	589	$	585
Due after one year through five years	654		643
Due after five years through ten years	1,463		1,429
Due after ten years	705		669
	3,411		3,326
Mortgage-backed securities	11,092		10,383
	$	14,503	$	13,709

Investment Securities in Continuous Unrealized Loss Position

A summary of investment securities that as of September 30, 2024 and December 31, 2023 had been in a continuous unrealized loss position for less than twelve months and those that had been in a continuous unrealized loss position for twelve months or longer follows:

	Less Than 12 Months				12 Months or More
(Dollars in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
September 30, 2024
Investment securities available for sale:
U.S. Treasury and federal agencies	$	125	$	—	$	3,069	$	26
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	395		2		128		1
Residential	227		—		1,760		77
Other debt securities	—		—		64		2
	747		2		5,021		106
Investment securities held to maturity:
U.S. Treasury and federal agencies	—		—		949		14
Obligations of states and political subdivisions	26		—		2,192		71
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	—		—		1,957		81
Residential	—		—		7,318		646
Privately issued	—		—		31		3
	26		—		12,447		815
Total	$	773	$	2	$	17,468	$	921
December 31, 2023
Investment securities available for sale:
U.S. Treasury and federal agencies	$	229	$	1	$	7,474	$	112
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	74		1		330		8
Residential	151		2		1,959		116
Other debt securities	6		—		154		11
	460		4		9,917		247
Investment securities held to maturity:
U.S. Treasury and federal agencies	50		—		924		31
Obligations of states and political subdivisions	218		3		2,172		64
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	328		9		1,575		121
Residential	955		11		7,139		791
Privately issued	—		—		34		5
	1,551		23		11,844		1,012
Total	$	2,011	$	27	$	21,761	$	1,259