Investment securities (Tables)

12 Months Ended

Dec. 31, 2025

Investments, Debt and Equity Securities [Abstract]

Amortized Cost and Estimated Fair Value of Investment Securities

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


(Dollars in millions)	Amortized Cost (a)		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
December 31, 2025
Investment securities available for sale:
U.S. Treasury	$	6,302	$	43	$	2	$	6,343
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	4,738		79		1		4,816
Residential	11,953		148		59		12,042
Other	1		—		—		1
	22,994		270		62		23,202
Investment securities held to maturity:
U.S. Treasury	445		—		4		441
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	2,007		—		74		1,933
Residential	7,816		10		619		7,207
Privately issued	32		12		—		44
State and political subdivisions	2,129		—		40		2,089
Other	1		—		—		1
	12,430		22		737		11,715
Total debt securities	$	35,424	$	292	$	799	$	34,917
Equity and other securities:
Readily marketable equity — at fair value	$	280	$	3	$	2	$	281
Other — at cost	736		—		—		736
Total equity and other securities	$	1,016	$	3	$	2	$	1,017

December 31, 2024
Investment securities available for sale:
U.S. Treasury	$	7,945	$	13	$	27	$	7,931
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	3,739		8		45		3,702
Residential	7,368		13		167		7,214
Other	2		—		—		2
	19,054		34		239		18,849
Investment securities held to maturity:
U.S. Treasury	1,015		—		14		1,001
Mortgage-backed securities:
Government issued or guaranteed:
Commercial	2,034		—		157		1,877
Residential	8,773		—		961		7,812
Privately issued	37		9		—		46
State and political subdivisions	2,335		—		117		2,218
Other	1		—		—		1
	14,195		9		1,249		12,955
Total debt securities	$	33,249	$	43	$	1,488	$	31,804
Equity and other securities:
Readily marketable equity — at fair value	$	235	$	3	$	3	$	235
Other — at cost	772		—		—		772
Total equity and other securities	$	1,007	$	3	$	3	$	1,007

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(a)Amortized cost balances of debt securities exclude accrued interest receivable of $187 million and $176 million at December 31, 2025 and 2024, respectively, which is included in Accrued interest and other assets in the Company's Consolidated Balance Sheet.

Debt Securities, Held-to-Maturity, Credit Quality Indicator

As of December 31, 2025, the latest available investment ratings of obligations of states and political subdivisions, privately issued mortgage-backed securities and other debt securities were as follows:


					Average Credit Rating of Fair Value Amount
(Dollars in millions)	Amortized Cost		Fair Value		A or Better		Not Rated
State and political subdivisions	$	2,129	$	2,089	$	2,079	$	10
Privately issued mortgage-backed securities	32		44		—		44
Other	2		2		—		2

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

At December 31, 2025, the amortized cost and fair value of debt securities by contractual maturity were as follows:


(Dollars in millions)	Amortized Cost		Fair Value
Debt securities available for sale:
Due in one year or less	$	3,076	$	3,085
Due after one year through five years	3,227		3,259
Due after five years through ten years	—		—
Due after ten years	—		—
	6,303		6,344
Mortgage-backed securities	16,691		16,858
	$	22,994	$	23,202
Debt securities held to maturity:
Due in one year or less	$	408	$	405
Due after one year through five years	377		375
Due after five years through ten years	1,326		1,313
Due after ten years	464		438
	2,575		2,531
Mortgage-backed securities	9,855		9,184
	$	12,430	$	11,715

There were no significant gross realized gains or losses from sales of investment securities in 2025 and 2023. Gross realized gains and losses from the sales of investment securities totaled $27 million and $15 million in 2024, respectively.

At December 31, 2025 and 2024, investment securities with carrying values of $5.3 billion (including $67 million related to repurchase transactions) and $6.2 billion (including $71 million related to repurchase transactions), respectively, were pledged to secure borrowings, lines of credit and governmental deposits as described in note 8.

M&T BANK CORP 10-K