

(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value
AFS investment securities:
March 31, 2024
U.S. Treasury	$	565,128	$	4	$	(193)	$	564,939
Agency	1,734		—		(64)		1,670
Corporate	471,426		243		(32,787)		438,882

Collateralized mortgage obligations	149,765		—		(1,235)		148,530

Total AFS investment securities	$	1,188,053	$	247	$	(34,279)	$	1,154,021





December 31, 2023
U.S. Treasury	$	538,899	$	381	$	(24)	$	539,256
Agency	1,941		—		(73)		1,868
Corporate	481,499		52		(35,208)		446,343

Collateralized mortgage obligations	153,701		—		(1,097)		152,604

Total AFS investment securities	$	1,176,040	$	433	$	(36,402)	$	1,140,071



(Dollars in thousands)	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrecognized Gain		Gross Unrecognized Loss		Estimated Fair Value
HTM investment securities:
March 31, 2024

Municipal bonds	$	1,145,902	$	(115)	$	1,145,787	$	264	$	(228,193)	$	917,858
Collateralized mortgage obligations	329,837		—		329,837		1,288		(10,867)		320,258
Mortgage-backed securities	228,611		—		228,611		146		(35,422)		193,335
Other	16,246		—		16,246		—		—		16,246
Total HTM investment securities	$	1,720,596	$	(115)	$	1,720,481	$	1,698	$	(274,482)	$	1,447,697





December 31, 2023
Municipal bonds	$	1,146,244	$	(126)	$	1,146,118	$	819	$	(206,361)	$	940,576
Collateralized mortgage obligations	334,997		—		334,997		1,565		(9,570)		326,992
Mortgage-backed securities	232,157		—		232,157		310		(30,798)		201,669
Other	16,269		—		16,269		—		—		16,269
Total HTM investment securities	$	1,729,667	$	(126)	$	1,729,541	$	2,694	$	(246,729)	$	1,485,506

During the first quarter of 2023, the Company transferred $410.7 million of AFS collateralized mortgage obligations to HTM securities. The Company intends and has the ability to hold the securities transferred to maturity. The transfer of these securities was accounted for at fair value on the transfer date. The collateralized mortgage obligations had a net carrying amount of $360.3 million with a pre-tax unrealized loss of $50.4 million, which are accreted into interest income as yield adjustments through earnings over the remaining term of the securities. The amortization of the related net after-tax unrealized losses reported in accumulated other comprehensive loss offsets the effect on interest income for the accretion of the unrealized losses associated with the transferred securities. No gains or losses were recorded at the time of transfer.

Investment securities with carrying values of $2.36 billion and $2.80 billion as of March 31, 2024 and December 31, 2023, respectively, were pledged to other borrowings, secure public deposits, and for other purposes as required or permitted by law. Investment securities with carrying values of $2.17 billion and $1.41 billion as of March 31, 2024 and December 31, 2023, respectively, were pledged to the Federal Reserve's discount window to increase the Company’s access to funding and provide liquidity.

Unrealized gains and losses on AFS investment securities, net of tax, are recognized in stockholders’ equity as accumulated other comprehensive income or loss. At March 31, 2024, the Company had a net unrealized loss on AFS investment securities of $34.0 million, or $24.4 million net of tax in accumulated other comprehensive loss, compared to a net unrealized loss of $36.0 million, or $25.8 million net of tax in accumulated other comprehensive loss, at December 31, 2023.

For investment securities transferred from AFS to HTM, the net after-tax unrealized gains and losses at the date of transfer continue to be reported in stockholders’ equity as accumulated other comprehensive loss and are amortized over the remaining lives of the securities with an offsetting entry to interest income as an adjustment of yield in a manner consistent with the amortization of a premium or discount, with an offsetting entry to interest income for the accretion of the unrealized loss associated with the transferred securities. At March 31, 2024, the unrealized loss on investment securities transferred from AFS to HTM was $99.4 million, or $71.3 million net of tax. At December 31, 2023, the unrealized loss on investment securities transferred from AFS to HTM was $102.9 million, or $73.9 million net of tax.

The table below summarizes the number, fair value, and gross unrealized holding losses of the Company’s AFS investment securities in an unrealized loss position for which an allowance for credit losses has not been recorded as of the dates indicated, aggregated by investment category and length of time in a continuous loss position.


	March 31, 2024
	Less than 12 Months					12 Months or Longer					Total
(Dollars in thousands)	Number	Fair Value		Gross Unrealized Losses		Number	Fair Value		Gross Unrealized Losses		Number	Fair Value		Gross Unrealized Losses
AFS investment securities:
U.S. Treasury	21	$	515,076	$	(193)	—	$	—	$	—	21	$	515,076	$	(193)
Agency	—	—		—		4	1,670		(64)		4	1,670		(64)
Corporate	—	—		—		41	365,603		(32,787)		41	365,603		(32,787)

Collateralized mortgage obligations	—	—		—		28	148,530		(1,235)		28	148,530		(1,235)

Total AFS investment securities	21	$	515,076	$	(193)	73	$	515,803	$	(34,086)	94	$	1,030,879	$	(34,279)


	December 31, 2023
	Less than 12 Months					12 Months or Longer					Total
(Dollars in thousands)	Number	Fair Value		Gross Unrealized Losses		Number	Fair Value		Gross Unrealized Losses		Number	Fair Value		Gross Unrealized Losses
AFS investment securities:
U.S. Treasury	4	$	98,622	$	(24)	—	$	—	$	—	4	$	98,622	$	(24)
Agency	—	—		—		4	1,868		(73)		4	1,868		(73)
Corporate	1	4,989		(3)		47	431,353		(35,205)		48	436,342		(35,208)

Collateralized mortgage obligations	—	—		—		28	152,604		(1,097)		28	152,604		(1,097)

Total AFS investment securities	5	$	103,611	$	(27)	79	$	585,825	$	(36,375)	84	$	689,436	$	(36,402)

The Company reviews individual securities classified as AFS to determine whether unrealized losses are deemed credit related or due to other factors such as changes in interest rates and general market conditions. An ACL on AFS investment securities is recorded when unrealized losses have been deemed, through the Company’s qualitative assessment, to be credit related. Non-credit related unrealized losses on AFS investment securities, which may be attributed to changes in interest rates and other market-related factors, are not recorded through an ACL. Such declines are recorded as an adjustment to accumulated other comprehensive loss, net of tax. In the event the Company is required to sell or has the intent to sell an AFS security that has experienced a decline in fair value below its amortized cost, the Company writes the amortized cost of the security down to fair value in the current period.

The ACL for HTM investment securities is estimated on a collective basis, based on shared risk characteristics, and is determined at the individual security level when the Company deems a security to no longer possess shared risk characteristics. Credit losses on HTM investment securities are representative of the amount needed to reduce the amortized cost basis to reflect the net amount expected to be collected.

The Company determines credit losses on both AFS and HTM investment securities through the use of a discounted cash flow approach using the security’s effective interest rate. The ACL is measured as the amount by which an investment security’s amortized cost exceeds the net present value of expected future cash flows. However, the amount of credit losses for AFS investment securities is limited to the amount of a security’s unrealized loss. The ACL is established through a charge to provision for credit losses in current period earnings.

At March 31, 2024 and December 31, 2023, the Company had an ACL of $115,000 and $126,000, respectively, for HTM investment securities classified as municipal bonds. The following table presents a rollforward by major security type of the ACL on the Company's HTM debt securities as of and for the periods indicated:

The Company had no ACL for AFS investment securities at March 31, 2024 and December 31, 2023. The Company performed a qualitative assessment of these investments as of March 31, 2024 and determined that unrealized losses during the first quarter of 2024 were the result of general market conditions, including changes in interest rates, and does not believe the declines in fair value were credit related. As of March 31, 2024, the Company had not recorded credit losses on AFS securities that were in an unrealized loss position due to the high quality of the investments, with investment grade ratings, and many of them issued by U.S. government agencies. As of March 31, 2024, 62% of our AFS securities were U.S. Treasury, U.S. government agency, and U.S. government-sponsored enterprise securities. Additionally, the Company continues to receive contractual principal and interest payments in a timely manner. It is more likely than not that the Company will not be required to sell the securities prior to their anticipated recoveries, and at this time the Company does not intend to sell these securities. There was no provision for credit losses recognized for AFS investment securities during the three months ended March 31, 2024 and 2023.

At March 31, 2024 and December 31, 2023, there were no AFS or HTM securities in nonaccrual status. All securities in the portfolio were current with their contractual principal and interest payments. At March 31, 2024 and December 31, 2023, there were no securities purchased with deterioration in credit quality since their origination. At March 31, 2024 and December 31, 2023, there were no collateral dependent AFS or HTM securities.


	Three Months Ended
	March 31,		March 31,
(Dollars in thousands)	2024		2023
Amortized cost of AFS investment securities sold	$	—	$	304,182

Gross realized gains	$	—	$	986
Gross realized (losses)	—		(848)
Net realized gains on sales of AFS investment securities	$	—	$	138


	Due in One Year or Less				Due after One Year through Five Years				Due after Five Years through Ten Years				Due after Ten Years				Total
(Dollars in thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value
AFS investment securities:
U.S. Treasury	$	565,128	$	564,939	$	—	$	—	$	—	$	—	$	—	$	—	$	565,128	$	564,939
Agency	—		—		257		250		786		758		691		662		1,734		1,670
Corporate	33,006		32,995		233,484		231,709		204,936		174,178		—		—		471,426		438,882

Collateralized mortgage obligations	49		49		40,793		40,660		60,925		60,378		47,998		47,443		149,765		148,530

Total AFS investment securities	598,183		597,983		274,534		272,619		266,647		235,314		48,689		48,105		1,188,053		1,154,021
HTM investment securities:

Municipal bonds	—		—		26,337		24,621		38,068		34,154		1,081,497		859,083		1,145,902		917,858
Collateralized mortgage obligations	—		—		86		86		—		—		329,751		320,172		329,837		320,258
Mortgage-backed securities	—		—		1,918		1,977		3,476		3,527		223,217		187,831		228,611		193,335
Other	—		—		—		—		—		—		16,246		16,246		16,246		16,246
Total HTM investment securities	—		—		28,341		26,684		41,544		37,681		1,650,711		1,383,332		1,720,596		1,447,697
Total investment securities	$	598,183	$	597,983	$	302,875	$	299,303	$	308,191	$	272,995	$	1,699,400	$	1,431,437	$	2,908,649	$	2,601,718