Securities are classified as AFS on the consolidated balance sheets at the time of purchase. AFS securities include those securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity, and are carried at fair value on the consolidated balance sheets. Premiums and discounts on investment securities are amortized or accreted into interest income over the estimated life of the related securities using the effective interest method.


	June 30, 2026
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Securities AFS:
U.S. Treasury securities	$	288,288	$	492	$	4,078	$	284,702
U.S. government agency securities	27,121		—		344		26,777
State, county and municipals	367,314		471		17,559		350,226
Mortgage-backed securities	1,247,459		2,008		32,941		1,216,526
Corporate debt securities	127,865		2,231		1,364		128,732
Total securities AFS	$	2,058,047	$	5,202	$	56,286	$	2,006,963


	December 31, 2025
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Securities AFS:
U.S. Treasury securities	$	25,056	$	2	$	1,004	$	24,054
U.S. government agency securities	4,189		4		21		4,172
State, county and municipals	289,826		323		15,325		274,824
Mortgage-backed securities	513,715		3,898		20,832		496,781
Corporate debt securities	61,302		226		1,525		60,003
Total securities AFS	$	894,088	$	4,453	$	38,707	$	859,834


	Six Months Ended June 30,
(in thousands)	2026		2025
Securities AFS:
Gross gains	$	20	$	4
Gross losses	(56)		—
Gains (losses) on sales of securities AFS, net	$	(36)	$	4
Proceeds from sales of securities AFS *	$	282,219	$	1,250

* Includes proceeds of $220 million recognized on the sale of securities AFS upon acquisition of MidWestOne in 2026 for which no gain or loss was recognized in the income statement as the investment securities were marked to fair value through purchase accounting.

The majority of the mortgage-backed securities included in the securities portfolio were issued by U.S. government agencies and corporations. Investment securities with a carrying value of $511 million and $497 million, as of June 30, 2026 and December 31, 2025, respectively, were pledged as collateral to secure public deposits and borrowings, as applicable, and for liquidity or other purposes as required by regulation. Accrued interest on investment securities totaled $9 million and $5 million at June 30, 2026 and December 31, 2025, respectively, and is included in accrued interest receivable and other assets on the consolidated balance sheets.

The following table presents gross unrealized losses and the related estimated fair value of investment securities for which an allowance for credit losses has not been recorded, aggregated by investment category and length of time individual securities have been in a continuous unrealized loss position.


	June 30, 2026
	Less than 12 months				12 months or more				Total
($ in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Number of Securities
Securities AFS:
U.S. Treasury securities	$	235,186	$	3,017	$	14,446	$	1,061	$	249,632	$	4,078	14
U.S. government agency securities	24,520		327		2,220		17		26,740		344		11
State, county and municipals	108,977		2,710		204,041		14,849		313,018		17,559		427
Mortgage-backed securities	745,011		11,628		209,249		21,313		954,260		32,941		490
Corporate debt securities	42,508		467		20,653		897		63,161		1,364		43
Total	$	1,156,202	$	18,149	$	450,609	$	38,137	$	1,606,811	$	56,286	985


	December 31, 2025
	Less than 12 months				12 months or more				Total
($ in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Number of Securities
Securities AFS:
U.S. Treasury securities	$	—	$	—	$	14,598	$	1,004	$	14,598	$	1,004	1
U.S. government agency securities	411		—		2,825		21		3,236		21		8
State, county and municipals	7,002		38		229,648		15,287		236,650		15,325		388
Mortgage-backed securities	31,213		145		232,400		20,687		263,613		20,832		376
Corporate debt securities	2,332		20		40,093		1,505		42,425		1,525		30
Total	$	40,958	$	203	$	519,564	$	38,504	$	560,522	$	38,707	803

As of June 30, 2026 and December 31, 2025, no allowance for credit losses on AFS securities was recognized. The Company does not consider its securities AFS with unrealized losses to be attributable to credit-related factors, as the unrealized losses in each category have occurred as a result of changes in noncredit-related factors such as changes in interest rates, market spreads and market conditions subsequent to purchase, not credit deterioration. Furthermore, the Company does not have the intent to sell any of these AFS securities and believes that it is more likely than not that we will not have to sell any such securities before a recovery of cost.

The amortized cost and fair value of investment securities by contractual maturity are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties; as this is particularly inherent in mortgage-backed securities, these securities are not included in the maturity categories below.


As of June 30, 2026	Securities AFS
(in thousands)	Amortized Cost		Fair Value
Due in less than one year	$	65,181	$	64,748
Due in one year through five years	419,642		409,227
Due after five years through ten years	257,447		251,570
Due after ten years	68,318		64,892
	810,588		790,437
Mortgage-backed securities	1,247,459		1,216,526
Total investment securities	$	2,058,047	$	2,006,963

Other investments include “restricted” equity securities, equity securities with readily determinable fair values, and private company securities. As a member of the Federal Reserve Bank System and the Federal Home Loan Bank (“FHLB”) System, Nicolet is required to maintain an investment in the capital stock of these entities. These equity securities are “restricted” in that they can only be sold back to the respective institutions or another member institution at par. Therefore, they are less liquid than other exchange traded equity securities. As no ready market exists for these stocks, and they have no quoted market value, these investments are carried at cost. Also included are investments in other private companies that do not have quoted market prices, which are carried at cost less impairment charges, if any. The carrying value of other investments are summarized as follows.


(in thousands)	June 30, 2026		December 31, 2025
Federal Reserve Bank stock	$	67,009	$	33,541
Federal Home Loan Bank (“FHLB”) stock	13,359		7,735
Equity securities with readily determinable fair values	12,763		9,505
Other investments	23,444		12,466
Total other investments	$	116,575	$	63,247