The following tables summarize the amortized cost, gross unrealized gains and losses and approximate fair value of investment securities available for sale as of September 30, 2026 and December 31, 2025.


	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available for sale at September 30, 2026

U.S. Government-sponsored agency securities	$	81,543	$	—	$	(14,347)	$	67,196
State and municipal	982,812		—		(192,870)		789,942
U.S. Government-sponsored mortgage-backed securities	469,402		7		(83,370)		386,039
Foreign investment	1,500		—		(9)		1,491
Corporate obligations	7,017		11		(156)		6,872

Total available for sale	$	1,542,274	$	18	$	(290,752)	$	1,251,540


	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 September 30, 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 September 30, 2026
U.S. Government-sponsored agency securities	$	308,998	$	—	$	308,998	$	—	$	(52,277)	$	256,721
State and municipal	1,043,391		(245)		1,043,146		2		(237,783)		805,610
U.S. Government-sponsored mortgage-backed securities	520,807		—		520,807		—		(87,661)		433,146

Total held to maturity	$	1,873,196	$	(245)	$	1,872,951	$	2	$	(377,721)	$	1,495,477


	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 September 30, 2026 and December 31, 2025 of $18.6 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 evaluates available-for-sale debt securities in an unrealized loss position to determine whether credit loss allowance is required. In making this assessment, the Corporation considers the severity of the decline in fair value, changes in credit ratings, and other security-specific factors. Unrealized losses are recognized in other comprehensive income (loss). At September 30, 2026, management concluded that unrealized losses on available-for-sale securities were primarily attributable to changes in market interest rates and, therefore, no allowance for credit losses was recorded.

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.

The allowance for credit losses on investment securities held to maturity is a contra asset-valuation account. The Corporation estimates expected credit losses on investment securities held to maturity by major security type using historical loss information, current conditions, and reasonable and supportable forecasts. The Corporation elected to exclude accrued interest receivable on investment securities held to maturity from the estimate of credit losses.

No allowance for credit losses has been recorded for U.S. Government-sponsored agency and mortgage-backed securities due to the expectation of full collection of contractual cash flows.

With regard to securities issued by states and municipalities and other investment securities held to maturity, management considers credit ratings, issuer financial condition, and payment performance when evaluating expected credit losses. Furthermore, as of September 30, 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 September 30, 2026 and December 31, 2025 based on applying the long-term historical credit rate, as published by Moody's, for similarly rated securities.

On a quarterly basis, the Corporation monitors the credit quality of investment securities held to maturity through the use of issuer financial information and credit ratings. The following tables summarize the amortized cost of investment securities held to maturity at September 30, 2026 and December 31, 2025, aggregated by credit quality indicator.


	September 30, 2026
	U.S. Government-sponsored agency securities (1)		State and municipal		U.S. Government-sponsored mortgage-backed securities (1)		Total
Credit Rating:
Aaa	$	308,998	$	73,549	$	520,807	$	903,354
Aa1	—		216,863		—		216,863
Aa2	—		148,671		—		148,671
Aa3	—		187,732		—		187,732
A1	—		59,622		—		59,622
A2	—		10,192		—		10,192
A3	—		10,156		—		10,156

Non-rated	—		336,606		—		336,606
Total	$	308,998	$	1,043,391	$	520,807	$	1,873,196

(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.


	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

The following tables summarize, as of September 30, 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 September 30, 2026

U.S. Government-sponsored agency securities	$	30	$	(1)	$	67,166	$	(14,346)	$	67,196	$	(14,347)
State and municipal	96,818		(10,760)		693,124		(182,110)		789,942		(192,870)
U.S. Government-sponsored mortgage-backed securities	107,153		(4,070)		276,098		(79,300)		383,251		(83,370)
Foreign investment	1,491		(9)		—		—		1,491		(9)
Corporate obligations	982		(17)		5,319		(139)		6,301		(156)
Total investment securities available for sale	$	206,474	$	(14,857)	$	1,041,707	$	(275,895)	$	1,248,181	$	(290,752)


	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 September 30, 2026

U.S. Government-sponsored agency securities	$	(14,347)	13
State and municipal	(192,870)		617
U.S. Government-sponsored mortgage-backed securities	(83,370)		135
Foreign investment	(9)		1
Corporate obligations	(156)		4
Total investment securities available for sale	$	(290,752)	770


	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 at maturity.

Certain investment securities available for sale are reported in the financial statements at an amount less than their historical cost as indicated in the table below.


	September 30, 2026			December 31, 2025
Investment securities available for sale reported at less than historical cost:
Historical cost	$	1,538,933		$	1,436,638
Fair value	1,248,181			1,267,891
Gross unrealized losses	$	(290,752)		$	(168,747)
Percentage of the Corporation's investment securities available for sale in an unrealized loss position	99.7		%	90.1		%

The amortized cost and fair value of investment securities available for sale and held to maturity at September 30, 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 September 30, 2026
Due in one year or less	$	748	$	741	$	35,613	$	34,981
Due after one through five years	23,922		22,675		120,348		112,583
Due after five through ten years	329,137		277,575		265,174		216,934
Due after ten years	719,065		564,510		931,254		697,833
	1,072,872		865,501		1,352,389		1,062,331
U.S. Government-sponsored mortgage-backed securities	469,402		386,039		520,807		433,146

Total investment securities	$	1,542,274	$	1,251,540	$	1,873,196	$	1,495,477


	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 $3.1 billion and $3.3 billion were pledged at September 30, 2026 and December 31, 2025, respectively, primarily to secure borrowing capacity at the Federal Reserve Discount Window, as well as certain deposits, securities sold under agreements to repurchase, and for other purposes as permitted or required by law.

The book value of securities pledged and available under agreements to repurchase amounted to $122.5 million at September 30, 2026 and $119.8 million at December 31, 2025.

There were no sales of investment securities available for sale during the three and nine months ended September 30, 2026 and during the three months ended September 30, 2025. Gross gains and losses on the sales of investment securities available for sale for the nine months ended September 30, 2025 is shown below.


	Nine Months Ended September 30,
		2025
Sales of investment securities available for sale:
Gross gains		$	—
Gross losses		(8)

Net losses on sales of investment securities available for sale		$	(8)