Securities

3 Months Ended

Mar. 31, 2026

Investments, Debt and Equity Securities [Abstract]

5. Securities

Securities Available for Sale

This table provides detailed information about securities available for sale at March 31, 2026 and December 31, 2025 (in thousands):


March 31, 2026	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury	$	2,252,751	$	8,082	$	(3,120	)	$	2,257,713
U.S. Agencies		49,834		200		(66	)		49,968
Mortgage-backed		8,589,349		42,549		(344,025	)		8,287,873
State and political subdivisions		2,448,080		17,379		(94,003	)		2,371,456
Corporates		142,631		267		(3,217	)		139,681
Collateralized loan obligations		554,875		151		(831	)		554,195
Total	$	14,037,520	$	68,628	$	(445,262	)	$	13,660,886


December 31, 2025	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury	$	2,301,248	$	20,008	$	(441	)	$	2,320,815
U.S. Agencies		62,069		401		(100	)		62,370
Mortgage-backed		8,427,197		71,827		(331,151	)		8,167,873
State and political subdivisions		2,494,537		24,898		(72,847	)		2,446,588
Corporates		180,854		349		(4,088	)		177,115
Collateralized loan obligations		533,995		504		(119	)		534,380
Total	$	13,999,900	$	117,987	$	(408,746	)	$	13,709,141

The following table presents contractual maturity information for securities available for sale at March 31, 2026 (in thousands):


	Amortized		Fair
	Cost		Value
Due in 1 year or less	$	776,270	$	777,228
Due after 1 year through 5 years		2,284,188		2,279,354
Due after 5 years through 10 years		599,727		589,950
Due after 10 years		1,787,986		1,726,481
Total		5,448,171		5,373,013
Mortgage-backed securities		8,589,349		8,287,873
Total securities available for sale	$	14,037,520	$	13,660,886

Securities may be disposed of before contractual maturities due to sales by the Company or because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

The following table presents the sales of securities available for sale for the three months ended March 31, 2026 and 2025 (in thousands):


	Three Months Ended March 31,
	2026		2025
Proceeds from sales	$	51,771	$	611,423
Gross realized gains		403		390
Gross realized losses		—		—

There were $12.7 billion and $13.4 billion of securities pledged to secure U.S. Government deposits, other public deposits, certain trust deposits, derivative transactions, and repurchase agreements at March 31, 2026 and December 31, 2025, respectively.

Accrued interest on securities available for sale totaled $74.5 million and $82.9 million as of March 31, 2026 and December 31, 2025, respectively, and is included in the Accrued income line on the Company’s Consolidated Balance Sheets. The total amount of accrued interest is excluded from the amortized cost of available-for-sale securities presented above. Further, the Company has elected not to measure an ACL for accrued interest receivable.

The following table shows the Company’s available-for-sale investments’ gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at March 31, 2026 and December 31, 2025 (in thousands):


	Less than 12 months							12 months or more							Total
March 31, 2026	Count		Fair Value		Unrealized Losses			Count		Fair Value		Unrealized Losses			Count		Fair Value		Unrealized Losses
Description of Securities
U.S. Treasury		77	$	594,413	$	(2,942	)		1	$	14,815	$	(178	)		78	$	609,228	$	(3,120	)
U.S. Agencies		1		7,569		(66	)		—		—		—			1		7,569		(66	)
Mortgage-backed		212		1,987,192		(18,766	)		798		2,696,163		(325,259	)		1,010		4,683,355		(344,025	)
State and political subdivisions		474		631,510		(14,306	)		837		806,914		(79,697	)		1,311		1,438,424		(94,003	)
Corporates		—		—		—			89		120,650		(3,217	)		89		120,650		(3,217	)
Collateralized loan obligations		32		317,287		(788	)		2		12,963		(43	)		34		330,250		(831	)
Total		796	$	3,537,971	$	(36,868	)		1,727	$	3,651,505	$	(408,394	)		2,523	$	7,189,476	$	(445,262	)


	Less than 12 months							12 months or more							Total
December 31, 2025	Count		Fair Value		Unrealized Losses			Count		Fair Value		Unrealized Losses			Count		Fair Value		Unrealized Losses
Description of Securities
U.S. Treasury		8	$	72,013	$	(88	)		2	$	30,234	$	(353	)		10	$	102,247	$	(441	)
U.S. Agencies		1		7,855		(100	)		—		—		—			1		7,855		(100	)
Mortgage-backed		82		757,160		(5,682	)		817		2,871,729		(325,469	)		899		3,628,889		(331,151	)
State and political subdivisions		152		515,364		(11,181	)		1,142		809,113		(61,666	)		1,294		1,324,477		(72,847	)
Corporates		1		2,990		(10	)		134		164,108		(4,078	)		135		167,098		(4,088	)
Collateralized loan obligations		20		164,531		(112	)		1		2,999		(7	)		21		167,530		(119	)
Total		264	$	1,519,913	$	(17,173	)		2,096	$	3,878,183	$	(391,573	)		2,360	$	5,398,096	$	(408,746	)

The unrealized losses in the Company’s investments were caused by changes in interest rates, and not from a decline in credit of the underlying issuers. The U.S. Treasury, U.S. Agency, and GSE mortgage-backed securities are all considered to be agency-backed securities with no risk of loss as they are either explicitly or implicitly guaranteed by the U.S. government. The changes in fair value in the agency-backed portfolios are solely driven by change in interest rates caused by changing economic conditions. The Company has no knowledge of any underlying credit issues and the cash flows underlying the debt securities have not changed and are not expected to be impacted by changes in interest rates.

For the State and political subdivision portfolio, the majority of the Company’s holdings are in general obligation bonds, which have a very low historical default rate due to issuers generally having unlimited taxing authority to service the debt. For the State and political, Corporates, and Collateralized loan obligations portfolios, the Company has a robust process for monitoring credit risk, including both pre-purchase and ongoing post-purchase credit reviews and analysis. The Company monitors credit ratings of all bond issuers in these segments and reviews available financial data, including market and sector trends.

As of March 31, 2026 and December 31, 2025, there was no ACL related to the Company’s available-for-sale securities as the decline in fair value did not result from credit issues.

Securities Held to Maturity

The following table provides detailed information about securities held to maturity at March 31, 2026 and December 31, 2025, respectively (in thousands):


March 31, 2026	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Allowance for Credit Losses			Net Carrying Amount
U.S. Treasury	$	38,256	$	—	$	(298	)	$	37,958	$	—		$	38,256
Mortgage-backed		2,463,304		87		(307,694	)		2,155,697		—			2,463,304
State and political subdivisions		3,201,678		12,919		(235,688	)		2,978,909		(3,357	)		3,198,321
Total	$	5,703,238	$	13,006	$	(543,680	)	$	5,172,564	$	(3,357	)	$	5,699,881


December 31, 2025	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Allowance for Credit Losses			Net Carrying Amount
U.S. Treasury	$	38,253	$	27	$	(37	)	$	38,243	$	—		$	38,253
Mortgage-backed		2,513,667		335		(305,040	)		2,208,962		—			2,513,667
State and political subdivisions		3,172,307		26,713		(195,760	)		3,003,260		(1,684	)		3,170,623
Total	$	5,724,227	$	27,075	$	(500,837	)	$	5,250,465	$	(1,684	)	$	5,722,543

The following table presents contractual maturity information for securities held to maturity at March 31, 2026 (in thousands):


	Amortized		Fair
	Cost		Value
Due in 1 year or less	$	124,608	$	124,506
Due after 1 year through 5 years		420,999		410,094
Due after 5 years through 10 years		862,412		823,822
Due after 10 years		1,831,915		1,658,445
Total		3,239,934		3,016,867
Mortgage-backed securities		2,463,304		2,155,697
Total securities held to maturity	$	5,703,238	$	5,172,564

Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

There were no sales of securities held to maturity during three months ended March 31, 2026 or 2025.

During the year ended December 31, 2022, securities with an amortized cost of $4.1 billion and a fair value of $3.8 billion were transferred from the available-for-sale classification to the held-to-maturity classification as the Company has the positive intent and ability to hold these securities to maturity. The transfers of securities were made at fair value at the time of transfer. The unrealized holding gain or loss at the time of transfer is retained in AOCI and will be amortized over the remaining life of the securities, offsetting the related amortization of discount or premium on the transferred securities. No gains or losses were recognized at the time of the transfers. The amortized cost balance of securities held to maturity in the tables above includes a net unamortized unrealized loss of $132.1 million and $139.2 million at March 31, 2026 and December 31, 2025, respectively.

Accrued interest on securities held to maturity totaled $25.2 million and $28.0 million as of March 31, 2026 and December 31, 2025, respectively, and is included in the Accrued income line on the Company’s Consolidated Balance Sheets. The total amount of accrued interest is excluded from the amortized cost of held-to-maturity securities presented above. Further, the Company has elected not to measure an ACL for accrued interest receivable.

The following table shows the Company’s held-to-maturity investments’ gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at March 31, 2026 and December 31, 2025, respectively (in thousands):


	Less than 12 months							12 months or more							Total
March 31, 2026	Count		Fair Value		Unrealized Losses			Count		Fair Value		Unrealized Losses			Count		Fair Value		Unrealized Losses
U.S. Treasury		7	$	37,958	$	(298	)		—	$	—	$	—			7	$	37,958	$	(298	)
Mortgage-backed		14		172,121		(1,682	)		262		1,951,706		(306,012	)		276		2,123,827		(307,694	)
State and political subdivisions		260		949,911		(55,117	)		1,353		1,493,930		(180,571	)		1,613		2,443,841		(235,688	)
Total		281	$	1,159,990	$	(57,097	)		1,615	$	3,445,636	$	(486,583	)		1,896	$	4,605,626	$	(543,680	)


	Less than 12 months							12 months or more							Total
December 31, 2025	Count		Fair Value		Unrealized Losses			Count		Fair Value		Unrealized Losses			Count		Fair Value		Unrealized Losses
U.S. Treasury		3	$	15,913	$	(37	)		—	$	—	$	—			3	$	15,913	$	(37	)
Mortgage-backed		10		147,066		(918	)		262		1,998,984		(304,122	)		272		2,146,050		(305,040	)
State and political subdivisions		146		687,180		(41,122	)		1,354		1,480,709		(154,638	)		1,500		2,167,889		(195,760	)
Total		159	$	850,159	$	(42,077	)		1,616	$	3,479,693	$	(458,760	)		1,775	$	4,329,852	$	(500,837	)

The unrealized losses in the Company’s held-to-maturity portfolio were caused by changes in the interest rate environment. The U.S. Treasury and GSE mortgage-backed securities are considered to be agency-backed securities with no risk of loss as they are either explicitly or implicitly guaranteed by the U.S. government. Therefore, the Company’s expected lifetime loss for these portfolios is zero and there is no ACL recorded for these portfolios. The Company has no knowledge of any underlying credit issues and the cash flows underlying the debt securities have not changed and are not expected to be impacted by changes in interest rates.

For the State and political subdivision portfolio, the Company’s holdings are in general obligation bonds as well as private placement bonds, which have very low historical default rates due to issuers generally having unlimited taxing authority to service the debt. The Company has a robust process for monitoring credit risk, including both pre-purchase and ongoing post-purchase credit reviews and analysis. The Company monitors credit ratings of all bond issuers in these segments and reviews available financial data, including market and sector trends. The underlying bonds are evaluated for credit losses in conjunction with management’s estimate of the ACL based on credit rating.

The following tables show the amortized cost basis by credit rating of the Company’s held-to-maturity State and political subdivisions bond investments at March 31, 2026 and December 31, 2025 (in thousands):


	Amortized Cost Basis by Credit Rating - HTM Debt Securities
March 31, 2026	AAA		AA		A		BBB		BB		B		CCC-C		Total
State and political subdivisions:
Competitive	$	47,376	$	51,712	$	372,892	$	804,924	$	30,295	$	23,100	$	13,604	$	1,343,903
Utilities		827,336		902,260		110,407		15,316		2,456		—		—		1,857,775
Total state and political subdivisions	$	874,712	$	953,972	$	483,299	$	820,240	$	32,751	$	23,100	$	13,604	$	3,201,678


	Amortized Cost Basis by Credit Rating - HTM Debt Securities
December 31, 2025	AAA		AA		A		BBB		BB		B		CCC-C		Total
State and political subdivisions:
Competitive	$	46,933	$	51,390	$	379,973	$	812,061	$	34,105	$	23,326	$	14,424	$	1,362,212
Utilities		899,088		777,880		114,845		15,824		2,458		—		—		1,810,095
Total state and political subdivisions	$	946,021	$	829,270	$	494,818	$	827,885	$	36,563	$	23,326	$	14,424	$	3,172,307

Competitive held-to-maturity securities include not-for-profit enterprises that provide public functions such as housing, higher education or healthcare, but do so in a competitive environment. It also includes project financings that can have relatively high enterprise risk, such as deals backed by revenues from sports or convention facilities or start-up transportation revenues.

Utilities are public enterprises providing essential services with a monopoly or near-monopoly over the service area. This includes environmental utilities (water, sewer, solid waste), power utilities (electric distribution and generation, gas), and transportation utilities (airports, parking, toll roads, mass transit, ports).

The following table presents the aging of past due held-to-maturity securities at March 31, 2026 (in thousands):


March 31, 2026	30-89 Days Past Due and Accruing		Greater than 90 Days Past Due and Accruing		Non- Accrual		Total Past Due		Current		Total
State and political subdivisions:
Competitive	$	131	$	16,470	$	—	$	16,601	$	1,327,302	$	1,343,903
Utilities		—		—		—		—		1,857,775		1,857,775
Total state and political subdivisions	$	131	$	16,470	$	—	$	16,601	$	3,185,077	$	3,201,678

All held-to-maturity securities were current and not past due at December 31, 2025.

Trading Securities

There were net unrealized losses of $6 thousand and $15 thousand on trading securities at March 31, 2026 and 2025, respectively. Net unrealized gains and losses are included in trading and investment banking income on the Company’s Consolidated Statements of Income. Securities sold not yet purchased totaled $8.3 million and $4.1

million at March 31, 2026 and December 31, 2025, respectively, and are classified within the Other liabilities line of the Company’s Consolidated Balance Sheets.

Other Securities

The table below provides detailed information for Other securities at March 31, 2026 and December 31, 2025 (in thousands):


	March 31, 2026		December 31, 2025
FRB and FHLB stock	$	137,660	$	137,498
Equity securities with readily determinable fair values		12,604		14,690
Equity securities without readily determinable fair values		535,326		524,112
Total	$	685,590	$	676,300

Investment in FRB stock is based on the capital structure of the investing bank, and investment in FHLB stock is mainly tied to the level of borrowings from the FHLB. These holdings are carried at cost. Equity securities with readily determinable fair values are generally traded on an exchange and market prices are readily available. Equity securities without readily determinable fair values include equity investments which are held by a subsidiary qualified as a Small Business Investment Company, as well as investments in low-income housing partnerships within the areas the Company serves. Unrealized gains or losses on equity securities with and without readily determinable fair values are recognized in the Investment securities gains, net line of the Company’s Consolidated Statements of Income.

The table below presents the changes in equity securities without readily determinable fair values for the three months ended March 31, 2026 and 2025 (in thousands):


	Three Months Ended March 31,
	2026			2025
Beginning balance	$	524,112		$	416,750
Acquisition of HTLF		—			121,769
Purchases of securities		33,664			24,003
Observable upward price adjustments		3,568			1,022
Observable downward price adjustments		(636	)		(6,273	)
Sales of securities and other activity		(25,382	)		(17,341	)
Ending balance	$	535,326		$	539,930

Investment Securities Gains, Net

The following table presents the components of Investment securities gains (losses), net for the three months ended March 31, 2026 and March 31, 2025 (in thousands):


	Three Months Ended March 31,
	2026			2025
Investment securities gains (losses), net
Available-for-sale debt securities:
Gains realized on sales	$	403		$	390
Equity securities with readily determinable fair values:
Fair value adjustments, net		(287	)		144
Equity securities without readily determinable fair values:
Fair value adjustments, net		315			(5,243	)
Sales		2,615			(73	)
Total investment securities gains (losses), net	$	3,046		$	(4,782	)