Investment Securities (Tables)

6 Months Ended

Jun. 30, 2024

Investment Securities

Summary of available-for-sale securities

Available-for-sale securities are summarized as follows as of the dates indicated:

	June 30, 2024
	Amortized		Gross		Gross
	cost		unrealized gains		unrealized losses		Fair value
U.S. Treasury securities	$	74,518	$	3	$	(1,333)	$	73,188
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		230,597		131		(33,668)		197,060
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		486,723		91		(68,685)		418,129
Municipal securities		80		—		—		80
Corporate debt		2,000		—		(112)		1,888
Other securities		731		—		—		731
Total investment securities available-for-sale	$	794,649	$	225	$	(103,798)	$	691,076

	December 31, 2023
	Amortized		Gross		Gross
	cost		unrealized gains		unrealized losses		Fair value
U.S. Treasury securities	$	74,508	$	—	$	(1,464)	$	73,044
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		233,264		57		(31,512)		201,809
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		417,155		—		(65,913)		351,242
Municipal securities		80		—		(1)		79
Corporate debt		2,000		—		(157)		1,843
Other securities		812		—		—		812
Total investment securities available-for-sale	$	727,819	$	57	$	(99,047)	$	628,829

Summary of unrealized losses for available-for-sale securities

The tables below summarize the available-for-sale securities with unrealized losses as of the dates shown, along with the length of the impairment period:

	June 30, 2024
	Less than 12 months				12 months or more				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	value		losses		value		losses		value		losses
U.S. Treasury securities	$	—	$	—	$	48,351	$	(1,333)	$	48,351	$	(1,333)
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		—		—		181,312		(33,668)		181,312		(33,668)
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		65,761		(445)		323,031		(68,240)		388,792		(68,685)
Municipal securities		—		—		80		—		80		—
Corporate debt		—		—		1,888		(112)		1,888		(112)
Total	$	65,761	$	(445)	$	554,662	$	(103,353)	$	620,423	$	(103,798)

	December 31, 2023
	Less than 12 months				12 months or more				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	value		losses		value		losses		value		losses
U.S. Treasury securities	$	—	$	—	$	73,044	$	(1,464)	$	73,044	$	(1,464)
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		9		—		199,000		(31,512)		199,009		(31,512)
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		138		(1)		351,104		(65,912)		351,242		(65,913)
Municipal securities		—		—		79		(1)		79		(1)
Corporate debt		—		—		1,843		(157)		1,843		(157)
Total	$	147	$	(1)	$	625,070	$	(99,046)	$	625,217	$	(99,047)

Summary of credit quality indicators, by fair value, of available-for-sale securities

The tables below summarize the credit quality indicators, by fair value, of available-for-sale securities as of the dates shown:

	June 30, 2024
	AA+		Not rated		Total
U.S. Treasury securities	$	73,188	$	—	$	73,188
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		197,060		—		197,060
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		418,129		—		418,129
Municipal securities		—		80		80
Corporate debt		—		1,888		1,888
Other securities		—		731		731
Total investment securities available-for-sale	$	688,377	$	2,699	$	691,076

	December 31, 2023
	AAA		Not rated		Total
U.S. Treasury securities	$	73,044	$	—	$	73,044
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		201,809		—		201,809
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		351,242		—		351,242
Municipal securities		—		79		79
Corporate debt		—		1,843		1,843
Other securities		—		812		812
Total investment securities available-for-sale	$	626,095	$	2,734	$	628,829

Summary of available-for-sale and held-to-maturity securities by maturity

A summary of the available-for-sale securities by maturity is shown in the following table as of June 30, 2024. Mortgage-backed securities may have actual maturities that differ from contractual maturities depending on the repayment characteristics and experience of the underlying financial instruments and are therefore not included in the table below. Additionally, the Company holds other available-for-sale securities with an amortized cost and fair value of $0.7 million as of June 30, 2024 that have no stated contractual maturity date.

	June 30, 2024
					Weighted
	Amortized Cost		Fair Value		Average Yield
U.S. Treasury securities
Within one year	$	49,693	$	49,235	3.94%
After one but within five years		24,825		23,953	2.77%
Total U.S. Treasury securities		74,518		73,188	3.55%
Municipal securities
Within one year		80		80	3.16%
Corporate debt
After five but within ten years		2,000		1,888	5.87%
Total	$	76,598	$	75,156

A summary of the held-to-maturity securities by maturity is shown in the following table as of June 30, 2024. Actual maturities of mortgage-backed securities may differ from scheduled maturities depending on the repayment characteristics and experience of the underlying financial instruments and are therefore not included in the table below.

	June 30, 2024
					Weighted
	Amortized Cost		Fair Value		Average Yield
U.S. Treasury securities
Within one year	$	24,937	$	24,534	3.18%
After one but within five years		24,550		23,808	3.10%
Total	$	49,487	$	48,342

Summary of held-to-maturity securities

Held-to-maturity investment securities are summarized as follows as of the dates indicated:

	June 30, 2024
			Gross		Gross
	Amortized		unrealized		unrealized
	cost		gains		losses		Fair value
U.S. Treasury securities	$	49,487	$	—	$	(1,145)	$	48,342
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		279,941		31		(37,427)		242,545
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		225,258		—		(47,256)		178,002
Total investment securities held-to-maturity	$	554,686	$	31	$	(85,828)	$	468,889

	December 31, 2023
			Gross		Gross
	Amortized		unrealized		unrealized
	cost		gains		losses		Fair value
U.S. Treasury securities	$	49,338	$	—	$	(1,004)	$	48,334
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		299,337		226		(34,552)		265,011
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		236,377		2		(45,396)		190,983
Total investment securities held-to-maturity	$	585,052	$	228	$	(80,952)	$	504,328

Summary of unrealized losses for held-to-maturity securities

The held-to-maturity portfolio included 155 securities which were in an unrealized loss position as of June 30, 2024, compared to 123 securities at December 31, 2023. The tables below summarize the held-to-maturity securities with unrealized losses as of the dates shown, along with the length of the impairment period:

	June 30, 2024
	Less than 12 months				12 months or more				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	value		losses		value		losses		value		losses
U.S. Treasury securities	$	—	$	—	$	48,342	$	(1,145)	$	48,342	$	(1,145)
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		32,855		(579)		205,990		(36,848)		238,845		(37,427)
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		1,636		(36)		176,367		(47,220)		178,003		(47,256)
Total	$	34,491	$	(615)	$	430,699	$	(85,213)	$	465,190	$	(85,828)

	December 31, 2023
	Less than 12 months				12 months or more				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	value		losses		value		losses		value		losses
U.S. Treasury securities	$	—	$	—	$	48,334	$	(1,004)	$	48,334	$	(1,004)
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		14,689		(72)		217,467		(34,480)		232,156		(34,552)
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		2,289		(37)		187,021		(45,359)		189,310		(45,396)
Total	$	16,978	$	(109)	$	452,822	$	(80,843)	$	469,800	$	(80,952)

Summary of credit quality indicators, by amortized cost, of held-to-maturity securities

The tables below summarize the credit quality indicators, by amortized cost, of held-to-maturity securities as of the dates shown:

	June 30, 2024		December 31, 2023
	AA+		AAA
U.S. Treasury securities	$	49,487	$	49,338
Mortgage-backed securities:
Residential mortgage pass-through securities issued or guaranteed by U.S. government agencies or sponsored enterprises		279,941		299,337
Other residential MBS issued or guaranteed by U.S. government agencies or sponsored enterprises		225,258		236,377
Total investment securities held-to-maturity	$	554,686	$	585,052