
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available for sale at March 31, 2026

U.S. Government-sponsored agency securities	$	86,447	$	—	$	(11,094)	$	75,353
State and municipal	993,176		62		(115,858)		877,380
U.S. Government-sponsored mortgage-backed securities	473,939		1,136		(64,620)		410,455
Foreign investment	1,500		—		—		1,500
Corporate obligations	7,985		—		(256)		7,729

Total available for sale	$	1,563,047	$	1,198	$	(191,828)	$	1,372,417


	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available for sale at December 31, 2025

U.S. Government-sponsored agency securities	$	87,936	$	—	$	(11,837)	$	76,099
State and municipal	993,911		225		(91,842)		902,294
U.S. Government-sponsored mortgage-backed securities	482,702		1,600		(64,792)		419,510
Foreign investment	1,500		—		—		1,500
Corporate obligations	7,974		1		(276)		7,699

Total available for sale	$	1,574,023	$	1,826	$	(168,747)	$	1,407,102

The following tables summarize the amortized cost, gross unrealized gains and losses, approximate fair value and allowance for credit losses on investment securities held to maturity as of March 31, 2026 and December 31, 2025.


	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Held to maturity at March 31, 2026
U.S. Government-sponsored agency securities	$	319,475	$	—	$	319,475	$	—	$	(44,709)	$	274,766
State and municipal	1,066,149		(245)		1,065,904		424		(162,047)		904,526
U.S. Government-sponsored mortgage-backed securities	552,106		—		552,106		—		(70,463)		481,643

Total held to maturity	$	1,937,730	$	(245)	$	1,937,485	$	424	$	(277,219)	$	1,660,935


	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Held to maturity at December 31, 2025
U.S. Government-sponsored agency securities	$	324,643	$	—	$	324,643	$	—	$	(46,693)	$	277,950
State and municipal	1,069,653		(245)		1,069,408		868		(137,706)		932,815
U.S. Government-sponsored mortgage-backed securities	577,488		—		577,488		—		(69,966)		507,522

Total held to maturity	$	1,971,784	$	(245)	$	1,971,539	$	868	$	(254,365)	$	1,718,287

Accrued interest on investment securities available for sale and held to maturity at March 31, 2026 and December 31, 2025 of $19.2 million and $21.9 million, respectively, is included in the "Interest receivable" line on the Corporation's Consolidated Condensed Balance Sheets. The total amount of accrued interest is excluded from the amortized cost of available for sale and held to maturity securities presented above.

In determining the allowance for credit losses on investment securities available for sale that are in an unrealized loss position, the Corporation first assesses whether it intends to sell, or it is more likely than not that it will be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through the income statement.

For investment securities available for sale that do not meet the aforementioned criteria, the Corporation evaluates whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, the Corporation considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded for the credit loss, limited by the amount that the fair value is less than the amortized cost basis. Unrealized losses that have not been recorded through an allowance for credit losses are recognized in other comprehensive income (loss).

Adjustments to the allowance are reported in the income statement as a component of the provision for credit losses. The Corporation has made the accounting policy election to exclude accrued interest receivable on investment securities available for sale from the estimate of credit losses.

Investment securities available for sale are charged off against the allowance or, in the absence of any allowance, written down through the income statement when deemed uncollectible or when either of the aforementioned criteria regarding intent or requirement to sell is met. The Corporation did not record an allowance for credit losses on its investment securities available for sale as the unrealized losses were attributable to changes in interest rates, not credit quality.

The allowance for credit losses on investment securities held to maturity is a contra asset-valuation account that is deducted from the amortized cost basis of investment securities held to maturity to present the net amount expected to be collected. Investment securities held to maturity are charged off against the allowance when deemed uncollectible. Adjustments to the allowance are reported in the income statement as a component of the provision for credit losses.

The Corporation measures expected credit losses on investment securities held to maturity on a collective basis by major security type with each type sharing similar risk characteristics, and considers historical credit loss information that is adjusted for current conditions and reasonable and supportable forecasts. The Corporation has made the accounting policy election to exclude accrued interest receivable on investment securities held to maturity from the estimate of credit losses.

With regard to U.S. Government-sponsored agency and U.S. Government-sponsored mortgage-backed securities, all of these securities are issued by a U.S. Government-sponsored entity and have an implicit or explicit government guarantee; therefore, no allowance for credit losses has been recorded for these securities.

With regard to securities issued by states and municipalities and other investment securities held to maturity, management considers (1) issuer bond ratings, (2) historical loss rates for given bond ratings, (3) the financial condition of the issuer, and (4) whether issuers continue to make timely principal and interest payments under the contractual terms of the securities. Historical loss rates associated with securities having similar grades as those in the Corporation's portfolio have been insignificant. Furthermore, as of March 31, 2026, there were no past due principal and interest payments associated with these securities.

The balance of the allowance for credit losses on investment securities held to maturity remained unchanged at $245,000 as of March 31, 2026 and December 31, 2025 based on applying the long-term historical credit rate, as published by Moody's, for similar rated securities.

On a quarterly basis, the Corporation monitors the credit quality of investment securities held to maturity through the use of credit ratings. The following tables summarize the amortized cost of investment securities held to maturity at March 31, 2026 and December 31, 2025, aggregated by credit quality indicator.


	March 31, 2026
	U.S. Government-sponsored agency securities (1)		State and municipal		U.S. Government-sponsored mortgage-backed securities (1)		Total
Credit Rating:
Aaa	$	319,475	$	73,681	$	552,106	$	945,262
Aa1	—		206,513		—		206,513
Aa2	—		161,553		—		161,553
Aa3	—		196,583		—		196,583
A1	—		59,628		—		59,628
A2	—		10,188		—		10,188
A3	—		10,150		—		10,150

Non-rated	—		347,853		—		347,853
Total	$	319,475	$	1,066,149	$	552,106	$	1,937,730


	December 31, 2025
	U.S. Government-sponsored agency securities (1)		State and municipal		U.S. Government-sponsored mortgage-backed securities (1)		Total
Credit Rating:
Aaa	$	324,643	$	75,598	$	577,488	$	977,729
Aa1	—		200,189		—		200,189
Aa2	—		172,127		—		172,127
Aa3	—		192,682		—		192,682
A1	—		59,631		—		59,631
A2	—		13,664		—		13,664
A3	—		6,670		—		6,670

Non-rated	—		349,092		—		349,092
Total	$	324,643	$	1,069,653	$	577,488	$	1,971,784

(1) U.S. Government-sponsored agency securities and U.S. Government-sponsored mortgage-backed securities are included within the Aaa credit rating category due to their explicit or implicit government guarantees, which provide a high level of assurance regarding the timely collection of principal and interest payments.

The following tables summarize, as of March 31, 2026 and December 31, 2025, investment securities available for sale in an unrealized loss position for which an allowance for credit losses has not been recorded, aggregated by security type and length of time in a continuous unrealized loss position.


	Less than 12 Months				12 Months or Longer				Total
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Investment securities available for sale at March 31, 2026

U.S. Government-sponsored agency securities	$	31	$	(1)	$	75,322	$	(11,093)	$	75,353	$	(11,094)
State and municipal	98,417		(2,912)		772,574		(112,946)		870,991		(115,858)
U.S. Government-sponsored mortgage-backed securities	12,325		(73)		305,646		(64,547)		317,971		(64,620)
Corporate obligations	990		(10)		6,709		(246)		7,699		(256)
Total investment securities available for sale	$	111,763	$	(2,996)	$	1,160,251	$	(188,832)	$	1,272,014	$	(191,828)


	Less than 12 Months				12 Months or Longer				Total
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Investment securities available for sale at December 31, 2025

U.S. Government-sponsored agency securities	$	—	$	—	$	76,099	$	(11,837)	$	76,099	$	(11,837)
State and municipal	5,468		(11)		861,410		(91,830)		866,878		(91,841)
U.S. Government-sponsored mortgage-backed securities	4,885		(10)		313,353		(64,783)		318,238		(64,793)
Corporate obligations	—		—		6,676		(276)		6,676		(276)
Total investment securities available for sale	$	10,353	$	(21)	$	1,257,538	$	(168,726)	$	1,267,891	$	(168,747)

The following tables summarize investment securities available for sale in an unrealized loss position for which an allowance for credit losses has not been recorded, aggregated by security type and the number of securities in the portfolio as of the dates indicated.


	Gross Unrealized Losses		Number of Securities
Investment securities available for sale at March 31, 2026

U.S. Government-sponsored agency securities	$	(11,094)	13
State and municipal	(115,858)		609
U.S. Government-sponsored mortgage-backed securities	(64,620)		92
Corporate obligations	(256)		6
Total investment securities available for sale	$	(191,828)	720


	Gross Unrealized Losses		Number of Securities
Investment securities available for sale at December 31, 2025

U.S. Government-sponsored agency securities	$	(11,837)	12
State and municipal	(91,841)		587
U.S. Government-sponsored mortgage-backed securities	(64,793)		89
Corporate obligations	(276)		5
Total investment securities available for sale	$	(168,747)	693

The unrealized losses in the Corporation’s investment portfolio were the result of changes in interest rates and not credit quality. As a result, the Corporation expects to recover the amortized cost basis over the term of the securities. The Corporation does not intend to sell the investments and it is not more likely than not that the Corporation will be required to sell the investments before recovery of their amortized cost basis, which may be maturity.


	March 31, 2026			December 31, 2025
Investment securities available for sale reported at less than historical cost:
Historical cost	$	1,463,842		$	1,436,638
Fair value	1,272,014			1,267,891
Gross unrealized losses	$	(191,828)		$	(168,747)
Percentage of the Corporation's investment securities available for sale in an unrealized loss position	88.1		%	90.1		%

In determining the fair value of the investment securities portfolio, the Corporation utilizes a third party for portfolio accounting services, including market value input, for those securities classified as Level 1 and Level 2 in the fair value hierarchy. The Corporation has obtained an understanding of what inputs are being used by the vendor in pricing the portfolio and how the vendor classified these securities based upon these inputs. From these discussions, the Corporation’s management is comfortable that the classifications are proper. The Corporation has gained trust in the data for two reasons: (a) independent spot testing of the data is conducted by the Corporation through obtaining market quotes from various brokers on a periodic basis; and (b) actual gains or losses resulting from the sale of certain securities has proven the data to be accurate over time. Fair value of securities classified as Level 3 in the valuation hierarchy was determined using a discounted cash flow model that incorporated market estimates of interest rates and volatility in markets that have not been active.

The amortized cost and fair value of investment securities available for sale and held to maturity at March 31, 2026 and December 31, 2025, by contractual maturity are shown below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity are shown separately.


	Available for Sale				Held to Maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Maturity Distribution at March 31, 2026
Due in one year or less	$	—	$	—	$	7,921	$	7,933
Due after one through five years	19,822		19,439		123,606		120,700
Due after five through ten years	257,933		237,111		233,917		210,251
Due after ten years	811,353		705,412		1,020,180		840,408
	1,089,108		961,962		1,385,624		1,179,292
U.S. Government-sponsored mortgage-backed securities	473,939		410,455		552,106		481,643

Total investment securities	$	1,563,047	$	1,372,417	$	1,937,730	$	1,660,935


	Available for Sale				Held to Maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Maturity Distribution at December 31, 2025
Due in one year or less	$	—	$	—	$	7,014	$	7,024
Due after one through five years	16,877		16,577		118,912		115,973
Due after five through ten years	241,803		227,493		228,224		210,125
Due after ten years	832,641		743,522		1,040,146		877,643
	1,091,321		987,592		1,394,296		1,210,765
U.S. Government-sponsored mortgage-backed securities	482,702		419,510		577,488		507,522

Total investment securities	$	1,574,023	$	1,407,102	$	1,971,784	$	1,718,287

Securities with a carrying value of approximately $3.2 billion and $3.3 billion were pledged at March 31, 2026 and December 31, 2025, respectively, to secure certain deposits and securities sold under repurchase agreements, and for other purposes as permitted or required by law.