Securities are classified as AFS or HTM 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. HTM securities include those securities which the Company has both the positive intent and ability to hold to maturity, and are carried at amortized cost 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.


	March 31, 2023
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Securities AFS:
U.S. Treasury securities	$	192,166	$	—	$	6,058	$	186,108
U.S. government agency securities	9,959		36		25		9,970
State, county and municipals	428,643		692		31,887		397,448
Mortgage-backed securities	350,712		—		39,091		311,621
Corporate debt securities	125,349		—		7,320		118,029
Total securities AFS	$	1,106,829	$	728	$	84,381	$	1,023,176


	December 31, 2022
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Securities AFS:
U.S. Treasury securities	$	192,116	$	—	$	8,286	$	183,830
U.S. government agency securities	2,133		—		33		2,100
State, county and municipals	433,733		123		35,668		398,188
Mortgage-backed securities	227,650		10		26,728		200,932
Corporate debt securities	140,712		3		8,147		132,568
Total securities AFS	$	996,344	$	136	$	78,862	$	917,618
Securities HTM:
U.S. Treasury securities	$	497,648	$	—	$	35,722	$	461,926
U.S. government agency securities	8,744		46		—		8,790
State, county and municipals	34,874		—		3,349		31,525
Mortgage-backed securities	137,862		—		16,751		121,111
Total securities HTM	$	679,128	$	46	$	55,822	$	623,352

On March 7, 2023, Nicolet executed the sale of $500 million (par value) U.S. Treasury held to maturity securities for a pre-tax loss of $38 million or an after-tax loss of $28 million. Proceeds from the sale were used to reduce existing FHLB borrowings with the remainder held in investable cash. As a result of the sale of securities previously classified as held to maturity, the remaining unsold portfolio of held to maturity securities, with a book value of $177 million, was reclassified to available for sale with a carrying value of approximately $157 million. The unrealized loss on this portfolio of $20 million increased the balance of accumulated other comprehensive loss $15 million, net of the deferred tax effect, and is subject to future market changes.


	Three Months Ended March 31,
(in thousands)	2023		2022
Securities AFS:
Gross gains	$	126	$	20
Gross losses	(339)		(5)
Gains (losses) on sales of securities AFS, net	$	(213)	$	15
Proceeds from sales of securities AFS	$	22,565	$	3,400
Securities HTM:
Gross gains	$	—	$	—
Gross losses	(37,723)		—
Gains (losses) on sales of securities HTM, net	$	(37,723)	$	—
Proceeds from sales of securities HTM	$	460,051	$	—

All mortgage-backed securities included in the tables above were issued by U.S. government agencies and corporations. Investment securities with a carrying value of $414 million and $883 million, as of March 31, 2023 and December 31, 2022, 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 $6 million at both March 31, 2023 and December 31, 2022, 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.


	March 31, 2023
	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	$	456	$	8	$	185,640	$	6,050	$	186,096	$	6,058	9
U.S. government agency securities	2,718		20		107		5		2,825		25		9
State, county and municipals	79,617		1,826		247,397		30,061		327,014		31,887		608
Mortgage-backed securities	35,724		2,158		275,897		36,933		311,621		39,091		464
Corporate debt securities	68,654		2,583		44,995		4,737		113,649		7,320		75
Total	$	187,169	$	6,595	$	754,036	$	77,786	$	941,205	$	84,381	1,165


	December 31, 2022
	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	$	448	$	14	$	183,382	$	8,272	$	183,830	$	8,286	9
U.S. government agency securities	2,083		32		17		1		2,100		33		9
State, county and municipals	277,546		18,041		86,569		17,627		364,115		35,668		812
Mortgage-backed securities	102,108		11,320		95,614		15,408		197,722		26,728		376
Corporate debt securities	114,887		6,186		12,938		1,961		127,825		8,147		90
Total	$	497,072	$	35,593	$	378,520	$	43,269	$	875,592	$	78,862	1,296
Securities HTM:
U.S. Treasury securities	$	—	$	—	$	461,926	$	35,722	$	461,926	$	35,722	6

State, county and municipals	17,591		1,594		11,654		1,755		29,245		3,349		58
Mortgage-backed securities	68,108		8,029		53,003		8,722		121,111		16,751		106
Total	$	85,699	$	9,623	$	526,583	$	46,199	$	612,282	$	55,822	170

During first quarter 2023, the Company recognized provision expense of $2.3 million related to the expected credit loss on its Signature Bank sub debt investment (acquired in an acquisition), and immediately charged-off the full investment. The Company does not consider its remaining 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. As of March 31, 2023 and December 31, 2022, no allowance for credit losses on AFS securities was recognized.

The Company evaluated the HTM securities and determined no allowance for credit losses was necessary at December 31, 2022. The U.S. Treasury and U.S. government agency securities are guaranteed by the U.S. government. For the state, county and municipal securities, management considered issuer bond ratings, historical loss rates by bond ratings, whether issuers continue to make timely principal and interest payments per the contractual terms of the investment securities, internal forecasts, and whether or not such investment securities provide insurance, other credit enhancement, or are pre-refunded by the issuers. For the mortgage-backed securities, all such securities were issued by U.S. government agencies and corporations, which are currently explicitly or implicitly guaranteed by the U.S. government and have a long history of no credit losses.

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 March 31, 2023	Securities AFS
(in thousands)	Amortized Cost		Fair Value
Due in less than one year	$	225,921	$	223,243
Due in one year through five years	173,794		163,788
Due after five years through ten years	223,776		201,296
Due after ten years	132,626		123,228
	756,117		711,555
Mortgage-backed securities	350,712		311,621
Total investment securities	$	1,106,829	$	1,023,176

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.


	March 31, 2023		December 31, 2022
(in thousands)	Amount		Amount
Federal Reserve Bank stock	$	32,708	$	32,219
Federal Home Loan Bank (“FHLB”) stock	10,174		18,625
Equity securities with readily determinable fair values	3,912		4,376
Other investments	10,688		10,066
Total other investments	$	57,482	$	65,286