The Company’s investment policy is designed primarily to provide and maintain liquidity, generate a favorable return on assets without incurring undue interest rate and credit risk, and complement the Bank’s lending activities.

The following tables present the amortized cost and fair value of investment securities, and the corresponding amounts of gross unrealized and unrecognized gains and losses including the corresponding amounts of gross unrealized gains and losses on investment securities available for sale recognized in AOCI, at the dates indicated:


	March 31, 2024
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(Dollars in thousands)
Investment securities available for sale:
U.S. government and agency securities	$	16,001	$	—	$	(2,584)	$	13,417
Municipal securities	83,788		6		(11,839)		71,955
Residential CMO and MBS(1)	519,152		1,128		(43,538)		476,742
Commercial CMO and MBS(1)	443,537		111		(34,180)		409,468
Corporate obligations	11,658		27		(494)		11,191
Other asset-backed securities	13,653		94		(10)		13,737
Total	$	1,087,789	$	1,366	$	(92,645)	$	996,510


	March 31, 2024
	Amortized Cost		Gross Unrecognized Gains		Gross Unrecognized Losses		Fair Value
	(Dollars in thousands)
Investment securities held to maturity:
U.S. government and agency securities	$	151,110	$	—	$	(29,980)	$	121,130
Residential CMO and MBS(1)	262,359		—		(17,439)		244,920
Commercial CMO and MBS(1)	320,537		—		(37,586)		282,951
Total	$	734,006	$	—	$	(85,005)	$	649,001


	December 31, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(Dollars in thousands)
Investment securities available for sale:
U.S. government and agency securities	$	16,047	$	—	$	(2,297)	$	13,750
Municipal securities	92,231		9		(12,715)		79,525
Residential CMO and MBS(1)	555,518		2,656		(46,125)		512,049
Commercial CMO and MBS(1)	538,910		88		(34,740)		504,258
Corporate obligations	7,745		2		(134)		7,613
Other asset-backed securities	17,336		31		(209)		17,158
Total	$	1,227,787	$	2,786	$	(96,220)	$	1,134,353


	December 31, 2023
	Amortized Cost		Gross Unrecognized Gains		Gross Unrecognized Losses		Fair Value
	(Dollars in thousands)
Investment securities held to maturity:
U.S. government and agency securities	$	151,075	$	—	$	(27,701)	$	123,374
Residential CMO and MBS(1)	267,204		—		(14,101)		253,103
Commercial CMO and MBS(1)	321,163		—		(35,190)		285,973
Total	$	739,442	$	—	$	(76,992)	$	662,450

The following table presents the amortized cost and fair value of investment securities by contractual maturity at the date indicated. Actual maturities may differ from contractual maturities because certain borrowers have the right to call or prepay obligations with or without call or prepayment penalties.


	March 31, 2024
	Securities Available for Sale				Securities Held to Maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	3,211	$	3,185	$	—	$	—
Due after one year through five years	5,296		5,033		—		—
Due after five years through ten years	39,359		35,988		93,269		77,426
Due after ten years	63,581		52,357		57,841		43,704
Total investment securities due at a single maturity date	111,447		96,563		151,110		121,130
MBS(1)	976,342		899,947		582,896		527,871
Total investment securities	$	1,087,789	$	996,510	$	734,006	$	649,001

There were no holdings of investment securities of any one issuer, other than the U.S. government and its agencies, in an amount greater than 10% of stockholders’ equity at March 31, 2024 and December 31, 2023.

The following tables present the gross unrealized losses and fair value of the Company’s investment securities available for sale for which an ACL on investment securities available for sale has not been recorded, aggregated by investment category and length of time the individual securities have been in a continuous unrealized loss position at the dates indicated:


	March 31, 2024
	Less than 12 Months				12 Months or Longer				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
	(Dollars in thousands)
U.S. government and agency securities	$	—	$	—	$	13,417	$	(2,584)	$	13,417	$	(2,584)
Municipal securities	2,981		(20)		64,458		(11,819)		67,439		(11,839)
Residential CMO and MBS(1)	57,366		(97)		301,367		(43,441)		358,733		(43,538)
Commercial CMO and MBS(1)	6,392		(68)		380,815		(34,112)		387,207		(34,180)
Corporate obligations	6,376		(348)		3,854		(146)		10,230		(494)
Other asset-backed securities	—		—		2,144		(10)		2,144		(10)
Total	$	73,115	$	(533)	$	766,055	$	(92,112)	$	839,170	$	(92,645)


	December 31, 2023
	Less than 12 Months				12 Months or Longer				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
	(Dollars in thousands)
U.S. government and agency securities	$	—	$	—	$	13,750	$	(2,297)	$	13,750	$	(2,297)
Municipal securities	3,548		(18)		71,458		(12,697)		75,006		(12,715)
Residential CMO and MBS(1)	—		—		358,316		(46,125)		358,316		(46,125)
Commercial CMO and MBS(1)	37,899		(228)		448,197		(34,512)		486,096		(34,740)
Corporate obligations	911		(20)		3,887		(114)		4,798		(134)
Other asset-backed securities	4,338		(22)		7,291		(187)		11,629		(209)
Total	$	46,696	$	(288)	$	902,899	$	(95,932)	$	949,595	$	(96,220)

The Company evaluated investment securities available for sale as of March 31, 2024 and December 31, 2023, and determined that any declines in fair value were attributable to changes in interest rates relative to where these investments fall within the yield curve and individual characteristics. Management monitors published credit ratings for adverse changes for all rated investment securities and none of these securities had a below investment grade credit rating as of either March 31, 2024 or December 31, 2023. In addition, the Company does not intend to sell these securities nor does the Company consider it more likely than not that it will be required to sell these securities before the recovery of the amortized cost basis, which may be upon maturity. Therefore, no ACL on investment securities available for sale was recorded as of March 31, 2024 and December 31, 2023.

The Company also evaluated investment securities held to maturity for current expected credit losses as of March 31, 2024 and December 31, 2023. There were no investment securities held to maturity classified as nonaccrual or past due as of March 31, 2024 and December 31, 2023, and all were issued by the U.S. government and its agencies and either explicitly or implicitly guaranteed by the U.S. government, highly rated by major credit rating agencies and had a long history of no credit losses. Accordingly, the Company did not measure expected credit losses on investment securities held to maturity since the historical credit loss information adjusted for current conditions and reasonable and supportable forecasts results in an expectation that nonpayment of the amortized cost basis is zero. Therefore, no ACL on investment securities held to maturity was recorded as of March 31, 2024 and December 31, 2023.

The following table presents the gross realized gains and losses on the sale of investment securities available for sale determined using the specific identification method for the dates indicated:


	March 31, 2024				December 31, 2023
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
State and local governments public deposits	$	235,829	$	219,951	$	238,060	$	224,879
FRB	619,972		520,685		845,098		742,197
Other securities pledged	54,376		48,457		54,636		49,032
Total	$	910,177	$	789,093	$	1,137,794	$	1,016,108

Accrued interest receivable excluded from the amortized cost of investment securities available for sale totaled $3.6 million and $3.8 million at March 31, 2024 and December 31, 2023, respectively. Accrued interest receivable excluded from the amortized cost on investment securities held to maturity totaled $2.2 million and $2.3 million at March 31, 2024 and December 31, 2023, respectively.

No amounts of accrued interest receivable on investment securities available for sale or held to maturity were reversed against interest income on investment securities during the three months ended March 31, 2024 and 2023.