
(dollars in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Allowance for Credit Losses		Estimated Fair Value
December 31, 2023
Investment securities available-for-sale:
U.S. treasury bonds	$	49,894	$	—	$	(1,993)	$	—	$	47,901
U.S. agency securities	729,090		—		(57,693)		—		671,397
Residential mortgage-backed securities	823,992		45		(96,684)		—		727,353
Commercial mortgage-backed securities	54,557		—		(4,993)		—		49,564
Municipal bonds	8,783		—		(293)		—		8,490
Corporate bonds	2,000		—		(300)		(17)		1,683
Total	$	1,668,316	$	45	$	(161,956)	$	(17)	$	1,506,388


(dollars in thousands)	Amortized Cost		Gross Unrecognized Gains		Gross Unrecognized Losses		Estimated Fair Value
December 31, 2023
Investment securities held-to-maturity:


Residential mortgage-backed securities	$	670,043	$	—	$	(79,980)	$	590,063
Commercial mortgage-backed securities	90,227		—		(12,867)		77,360
Municipal bonds	125,114		5		(8,540)		116,579
Corporate bonds	132,309		—		(14,729)		117,580
Total	1,017,693		$	5	$	(116,116)	$	901,582
Less: allowance for credit losses	(1,956)
Total amortized cost, net of allowance for credit losses	$	1,015,737


(dollars in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Allowance for Credit Losses		Estimated Fair Value
December 31, 2022
Investment securities available-for-sale:
U.S. treasury bonds	$	49,793	$	—	$	(3,466)	$	—	$	46,327
U.S. agency securities	747,777		—		(78,049)		—		669,728
Residential mortgage-backed securities	937,557		18		(117,072)		—		820,503
Commercial mortgage-backed securities	56,071		—		(5,858)		—		50,213
Municipal bonds	10,700		45		(658)		—		10,087
Corporate bonds	2,000		—		(175)		(17)		1,808
Total	$	1,803,898	$	63	$	(205,278)	$	(17)	$	1,598,666


(dollars in thousands)	Amortized Cost		Gross Unrecognized Gains		Gross Unrecognized Losses		Estimated Fair Value
December 31, 2022
Investment securities held-to-maturity:


Residential mortgage-backed securities	$	741,057	$	—	$	(88,390)	$	652,667
Commercial mortgage-backed securities	92,557		—		(11,993)		80,564
Municipal bonds	128,273		—		(12,092)		116,181
Corporate bonds	132,253		—		(12,958)		119,295
Total	1,094,140		$	—	$	(125,433)	$	968,707
Less: allowance for credit losses	(766)
Total amortized cost, net of allowance for credit losses	$	1,093,374

In addition, at December 31, 2023 and December 31, 2022, the Company held $25.7 million and $65.1 million in non marketable equity securities, respectively, in a combination of Federal Reserve System ("Federal Reserve Board," "Federal Reserve" or "FRB") and FHLB stocks, which are required to be held for regulatory purposes. The securities are carried at cost, classified as restricted securities, and periodically evaluated for impairment based on ultimate recovery of par value.

The Company reassessed classification of certain investments in the first quarter of 2022 and, effective March 31, 2022, it transferred a total of $1.1 billion of MBS, municipal bonds and corporate bonds from available-for-sale to held-to-maturity securities, including $237.0 million of securities acquired in the first quarter of 2022 for which its intention to hold to maturity was finalized. At the time of transfer, the Company reversed the allowance for credit losses associated with the available-for-sale securities through the provision for credit losses. The securities were transferred at their amortized cost basis, net of any remaining unrealized gain or loss reported in accumulated other comprehensive income. The related unrealized loss of $66.2 million was included in other comprehensive loss at the time of transfer and, as of December 31, 2023, $51.7 million remains in accumulated other comprehensive loss, to be amortized out through interest income as a yield adjustment over the remaining term of the securities. No gain or loss was recorded at the time of transfer. Subsequent to transfer, the allowance for credit losses on these securities was evaluated under the accounting policy for held-to-maturity securities.

Accrued interest receivable on investment securities totaled $7.6 million and $7.8 million at December 31, 2023 and December 31, 2022, respectively. The accrued interest on investment securities is excluded from the amortized cost of the securities and is reported in other assets in the Consolidated Balance Sheets.

The following tables summarize, by length of time, the Company's investment securities available-for-sale that have been in a continuous unrealized loss position and investment securities held-to-maturity that have been in a continuous unrecognized loss position:


		Less than 12 Months				12 Months or Greater				Total
(dollars in thousands)	Number of Securities	Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses
December 31, 2023
Investment securities available-for-sale:
U.S. treasury bonds	2	$	—	$	—	$	47,901	$	(1,993)	$	47,901	$	(1,993)
U.S. agency securities	78	3,084		(4)		668,313		(57,689)		671,397		(57,693)
Residential mortgage-backed securities	149	—		—		718,042		(96,684)		718,042		(96,684)
Commercial mortgage-backed securities	13	—		—		49,564		(4,993)		49,564		(4,993)
Municipal bonds	1	—		—		8,490		(293)		8,490		(293)
Corporate bonds	1	—		—		1,683		(300)		1,683		(300)
Total	244	$	3,084	$	(4)	$	1,493,993	$	(161,952)	$	1,497,077	$	(161,956)


		Less than 12 Months				12 Months or Greater				Total
(dollars in thousands)	Number of Securities	Estimated Fair Value		Unrecognized Losses		Estimated Fair Value		Unrecognized Losses		Estimated Fair Value		Unrecognized Losses
December 31, 2023
Investment securities held-to-maturity:


Residential mortgage-backed securities	142	$	—	$	—	$	590,063	$	(79,980)	$	590,063	$	(79,980)
Commercial mortgage-backed securities	16	—		—		77,360		(12,867)		77,360		(12,867)
Municipal bonds	40	—		—		113,031		(8,540)		113,031		(8,540)
Corporate bonds	30	—		—		105,523		(14,729)		105,523		(14,729)
Total	228	$	—	$	—	$	885,977	$	(116,116)	$	885,977	$	(116,116)


		Less than 12 Months				12 Months or Greater				Total
(dollars in thousands)	Number of Securities	Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses
December 31, 2022
Investment securities available-for-sale:
U.S. treasury bonds	2	$	—	$	—	$	46,327	$	(3,466)	$	46,327	$	(3,466)
U.S. agency securities	85	490,699		(58,437)		179,029		(19,612)		669,728		(78,049)
Residential mortgage-backed securities	157	3,994		—		808,697		(117,072)		812,691		(117,072)
Commercial mortgage-backed securities	14	471		(2)		49,742		(5,856)		50,213		(5,858)
Municipal bonds	1	—		—		8,299		(658)		8,299		(658)
Corporate bonds	1	—		—		1,825		(175)		1,825		(175)
Total	260	$	495,164	$	(58,439)	$	1,093,919	$	(146,839)	$	1,589,083	$	(205,278)


		Less than 12 Months				12 Months or Greater				Total
(dollars in thousands)	Number of Securities	Estimated Fair Value		Unrecognized Losses		Estimated Fair Value		Unrecognized Losses		Estimated Fair Value		Unrecognized Losses
December 31, 2022
Investment securities held-to-maturity:


Residential mortgage-backed securities	143	$	—	$	—	$	652,667	$	(88,390)	$	652,667	$	(88,390)
Commercial mortgage-backed securities	16	—		—		80,564		(11,993)		80,564		(11,993)
Municipal bonds	43	3,110		(45)		113,071		(12,047)		116,181		(12,092)
Corporate bonds	30	20,771		(3,183)		86,451		(9,775)		107,222		(12,958)
Total	232	$	23,881	$	(3,228)	$	932,753	$	(122,205)	$	956,634	$	(125,433)

Unrealized losses at December 31, 2023 were generally attributable to changes in market interest rates and interest spread relationships subsequent to the dates the investment securities were originally purchased, and not due to credit quality concerns on the investment securities. The Company measures its available-for-sale and held-to-maturity security portfolios for current expected credit losses as part of its allowance for credit losses analysis. There was no provision for credit losses recorded during the year ended December 31, 2023 and a reversal of credit losses of $603 thousand was recorded for the year ended December 31, 2022 on the available-for-sale securities portfolio. During the years ended December 31, 2023 and 2022, the Company recorded a provision for credit losses of $1.2 million and $766 thousand, respectively, on its investment securities held-to-maturity. As of December 31, 2023 and 2022, the Company had an allowance for credit losses outstanding of $17 thousand and $17 thousand, respectively, on its AFS securities and $2.0 million and $766 thousand, respectively, on its HTM securities.

The following table summarizes the Company's investment securities available-for-sale and investment securities held-to-maturity by contractual maturity. Expected maturities for MBS will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.


	December 31, 2023
(dollars in thousands)	Amortized Cost		Estimated Fair Value
Investment securities available-for-sale:
Within one year	$	141,266	$	137,159
One to five years	491,268		454,697
Five to ten years	136,583		119,582
Beyond ten years	20,650		18,050
Residential mortgage-backed securities	823,992		727,353
Commercial mortgage-backed securities	54,557		49,564

Less: allowance for credit losses	—		(17)
Total investment securities available-for-sale	1,668,316		1,506,388

Investment securities held-to-maturity:
Within one year	4,307		4,258
One to five years	56,444		54,589
Five to ten years	121,107		105,719
Beyond ten years	75,565		69,593
Residential mortgage-backed securities:	670,043		590,063
Commercial mortgage-backed securities	90,227		77,360

Less: allowance for credit losses	(1,956)		—
Total investment securities held-to-maturity	1,015,737		901,582
Total	$	2,684,053	$	2,407,970

During the years ended December 31, 2023, 2022 and 2021, proceeds from the sale or call of investment securities were $11.2 million, $14.6 million and $201.0 million, respectively. During the year ended December 31, 2023, gross realized gains on sales and calls of investment securities were $129 thousand and gross realized losses on sales of investment securities were $140 thousand. During the year ended December 31, 2022, gross realized gains on sales of investment securities were $18 thousand and gross realized losses on sales of investment securities were $187 thousand. During the year ended December 31, 2021, gross realized gains on sales of investment securities were $3.2 million and gross realized losses on sales of investment securities were $187 thousand.

At December 31, 2023 and 2022, the book value of securities pledged as collateral for certain government deposits, securities sold under agreements to repurchase and certain lines of credit with correspondent banks was $2.1 billion and $220.1 million, respectively, which were well in excess of required amounts in order to operationally provide significant reserve amounts for new business. As of December 31, 2023 and 2022, there were no holdings of securities of any one issuer, other than the U.S. Government and U.S. agency securities, which exceeded ten percent of shareholders’ equity.