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Investment securities (Tables) | 6 Months Ended
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Jun. 30, 2026
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
June 30, 2026 |  |  |  |  |  |  |
Investment securities available for sale: |  |  |  |  |  |  |
U.S. Treasury | $ | 3,227 |  |  | $ | 4 |  |  | $ | 4 |  |  | $ | 3,227 |
Mortgage-backed securities: |  |  |  |  |  |  |
Government issued or guaranteed: |  |  |  |  |  |  |
Commercial | 4,744 |  |  | 22 |  |  | 11 |  |  | 4,755 |
Residential (b) | 17,523 |  |  | 61 |  |  | 197 |  |  | 17,387 |
Other | 1 |  |  | — |  |  | — |  |  | 1 |
| 25,495 |  |  | 87 |  |  | 212 |  |  | 25,370 |
Investment securities held to maturity: |  |  |  |  |  |  |
U.S. Treasury | 398 |  |  | — |  |  | 3 |  |  | 395 |
Mortgage-backed securities: |  |  |  |  |  |  |
Government issued or guaranteed: |  |  |  |  |  |  |
Commercial | 1,996 |  |  | — |  |  | 92 |  |  | 1,904 |
Residential | 7,463 |  |  | 1 |  |  | 663 |  |  | 6,801 |
Privately issued | 28 |  |  | 11 |  |  | — |  |  | 39 |
State and political subdivisions | 2,022 |  |  | — |  |  | 43 |  |  | 1,979 |
Other | 1 |  |  | — |  |  | — |  |  | 1 |
| 11,908 |  |  | 12 |  |  | 801 |  |  | 11,119 |
Total debt securities | $ | 37,403 |  |  | $ | 99 |  |  | $ | 1,013 |  |  | $ | 36,489 |
Equity and other securities: |  |  |  |  |  |  |
Readily marketable equity — at fair value | $ | 242 |  |  | $ | 5 |  |  | $ | 2 |  |  | $ | 245 |
Other — at cost | 851 |  |  | — |  |  | — |  |  | 851 |
Total equity and other securities | $ | 1,093 |  |  | $ | 5 |  |  | $ | 2 |  |  | $ | 1,096 |
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 |
__________________________________________________________________________________ (a)Amortized cost balances of debt securities exclude accrued interest receivable of $173 million and $187 million at June 30, 2026 and December 31, 2025, respectively, which is included in Accrued interest and other assets in the Company's Consolidated Balance Sheet. (b)In July 2026, the Company transferred $8.3 billion of residential mortgage-backed securities from the available-for-sale portfolio to the held-to-maturity portfolio with gross unrealized gains of $32 million and gross unrealized losses of $24 million at the time of transfer.
Investment Securities in Continuous Unrealized Loss Position | A summary of debt investment securities that as of June 30, 2026 and December 31, 2025 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 |  | Total
(Dollars in millions) | Fair Value |  | Unrealized Losses |  | Fair Value |  | Unrealized Losses |  | Fair Value |  | Unrealized Losses
June 30, 2026 |  |  |  |  |  |  |  |  |  |  |
Investment securities available for sale: |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury | $ | 1,388 |  |  | $ | 4 |  |  | $ | — |  |  | $ | — |  |  | $ | 1,388 |  |  | $ | 4 |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |
Government issued or guaranteed: |  |  |  |  |  |  |  |  |  |  |
Commercial | 1,961 |  |  | 11 |  |  | 1 |  |  | — |  |  | 1,962 |  |  | 11 |
Residential | 9,794 |  |  | 135 |  |  | 1,091 |  |  | 62 |  |  | 10,885 |  |  | 197 |
Other | — |  |  | — |  |  | 1 |  |  | — |  |  | 1 |  |  | — |
| 13,143 |  |  | 150 |  |  | 1,093 |  |  | 62 |  |  | 14,236 |  |  | 212 |
Investment securities held to maturity: |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury | — |  |  | — |  |  | 395 |  |  | 3 |  |  | 395 |  |  | 3 |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |
Government issued or guaranteed: |  |  |  |  |  |  |  |  |  |  |
Commercial | 272 |  |  | 6 |  |  | 1,632 |  |  | 86 |  |  | 1,904 |  |  | 92 |
Residential | 1,231 |  |  | 19 |  |  | 5,110 |  |  | 644 |  |  | 6,341 |  |  | 663 |
Privately issued | — |  |  | — |  |  | 1 |  |  | — |  |  | 1 |  |  | — |
State and political subdivisions | 508 |  |  | 5 |  |  | 1,248 |  |  | 38 |  |  | 1,756 |  |  | 43 |
| 2,011 |  |  | 30 |  |  | 8,386 |  |  | 771 |  |  | 10,397 |  |  | 801 |
Total | $ | 15,154 |  |  | $ | 180 |  |  | $ | 9,479 |  |  | $ | 833 |  |  | $ | 24,633 |  |  | $ | 1,013 |
December 31, 2025 |  |  |  |  |  |  |  |  |  |  |
Investment securities available for sale: |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury | $ | — |  |  | $ | — |  |  | $ | 185 |  |  | $ | 2 |  |  | $ | 185 |  |  | $ | 2 |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |
Government issued or guaranteed: |  |  |  |  |  |  |  |  |  |  |
Commercial | 174 |  |  | 1 |  |  | 65 |  |  | — |  |  | 239 |  |  | 1 |
Residential | 488 |  |  | 2 |  |  | 1,303 |  |  | 57 |  |  | 1,791 |  |  | 59 |
Other | — |  |  | — |  |  | 1 |  |  | — |  |  | 1 |  |  | — |
| 662 |  |  | 3 |  |  | 1,554 |  |  | 59 |  |  | 2,216 |  |  | 62 |
Investment securities held to maturity: |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury | — |  |  | — |  |  | 391 |  |  | 4 |  |  | 391 |  |  | 4 |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |
Government issued or guaranteed: |  |  |  |  |  |  |  |  |  |  |
Commercial | 28 |  |  | — |  |  | 1,840 |  |  | 74 |  |  | 1,868 |  |  | 74 |
Residential | 139 |  |  | 1 |  |  | 6,287 |  |  | 618 |  |  | 6,426 |  |  | 619 |
Privately issued | 2 |  |  | — |  |  | — |  |  | — |  |  | 2 |  |  | — |
State and political subdivisions | 13 |  |  | — |  |  | 1,866 |  |  | 40 |  |  | 1,879 |  |  | 40 |
| 182 |  |  | 1 |  |  | 10,384 |  |  | 736 |  |  | 10,566 |  |  | 737 |
Total | $ | 844 |  |  | $ | 4 |  |  | $ | 11,938 |  |  | $ | 795 |  |  | $ | 12,782 |  |  | $ | 799 |
Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity | At June 30, 2026, 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 | $ | 1,356 |  |  | $ | 1,359 |
Due after one year through five years | 1,872 |  |  | 1,869 |
Due after five years through ten years | — |  |  | — |
Due after ten years | — |  |  | — |
| 3,228 |  |  | 3,228 |
Mortgage-backed securities | 22,267 |  |  | 22,142 |
| $ | 25,495 |  |  | $ | 25,370 |
Debt securities held to maturity: |  |  |
Due in one year or less | $ | 407 |  |  | $ | 404 |
Due after one year through five years | 392 |  |  | 391 |
Due after five years through ten years | 1,202 |  |  | 1,186 |
Due after ten years | 420 |  |  | 394 |
| 2,421 |  |  | 2,375 |
Mortgage-backed securities | 9,487 |  |  | 8,744 |
| $ | 11,908 |  |  | $ | 11,119 |
Realized Gain (Loss) on Investments | A summary of gross realized gains and gross realized losses from the sale of available-for-sale investment securities for the three-month and six-month periods ended June 30, 2026 and 2025 follows.
| Three Months Ended June 30, |  | Six Months Ended June 30,
(Dollars in millions) | 2026 |  | 2025 |  | 2026 |  | 2025
Gross realized gains | $ | — |  |  | $ | — |  |  | $ | 6 |  |  | $ | — |
Gross realized losses | — |  |  | — |  |  | (2) |  |  | — |
Net realized gains | $ | — |  |  | $ | — |  |  | $ | 4 |  |  | $ | — |

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