
(in thousands)	Amortized Cost(1)		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
September 30, 2024
Available-for-sale debt securities:
U.S. Treasury securities	$	278,200	$	—	$	(2,396)	$	275,804

Residential mortgage-backed securities	3,323,351		19,768		(112,263)		3,230,856


CRT securities	12,791		—		(789)		12,002
Total available-for-sale debt securities	3,614,342		19,768		(115,448)		3,518,662
Held-to-maturity debt securities:
Residential mortgage-backed securities	812,432		—		(84,689)		727,743
Total held-to-maturity debt securities	812,432		—		(84,689)		727,743
Equity securities							74,426
Total investment securities(2)							$	4,405,520
December 31, 2023
Available-for-sale debt securities:
U.S. Treasury securities	$	651,112	$	—	$	(14,639)	$	636,473
U.S. government agency securities	125,000		—		(18,408)		106,592
Residential mortgage-backed securities	2,782,734		540		(312,442)		2,470,832


CRT securities	13,636		—		(1,641)		11,995
Total available-for-sale debt securities	3,572,482		540		(347,130)		3,225,892
Held-to-maturity securities:
Residential mortgage-backed securities	865,477		—		(101,633)		763,844
Total held-to-maturity securities	865,477		—		(101,633)		763,844
Equity securities							51,825
Total investment securities(2)							$	4,143,194

(1) Excludes accrued interest receivable of $13.9 million and $9.5 million at September 30, 2024 and December 31, 2023, respectively, related to available-for-sale debt securities and $1.3 million and $1.4 million at September 30, 2024 and December 31, 2023, respectively, related to held-to-maturity debt securities that is recorded in accrued interest receivable and other assets on the consolidated balance sheets.

During the third quarter of 2024, the Company sold available-for-sale debt securities with an amortized cost basis of $1.2 billion, realizing a loss of $179.6 million, and repositioned the proceeds into a purchase of available-for-sale residential mortgage-backed securities with an amortized cost basis of $1.1 billion. In the first quarter of 2023, the Company sold available-for-sale U.S. Treasury securities with an amortized cost of $56.4 million and realized a gain of $489,000.

The amortized cost and estimated fair value as of September 30, 2024, excluding accrued interest receivable, of available-for-sale and held-to-maturity debt securities are presented below by contractual maturity. Actual maturities may differ from contractual maturities of mortgage-backed securities because borrowers may have the right to call or prepay obligations with or without prepayment penalties.


	Available-for-sale				Held-to-maturity
(in thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value

Due within one year	$	58,784	$	58,315	$	—	$	—
Due after one year through five years	219,416		217,489		—		—
Due after five years through ten years	13,774		13,001		—		—
Due after ten years	3,322,368		3,229,857		812,432		727,743
Total	$	3,614,342	$	3,518,662	$	812,432	$	727,743

The table below presents the weighted average yields for the Company’s available-for-sale debt securities for the nine months ended September 30, 2024. Weighted average yields are calculated based on amortized cost on a tax-exempt basis assuming a 21% federal tax rate, where applicable.


	U.S. Treasury securities		U.S. government agency securities		Residential mortgage-backed securities		CRT securities
Due within one year	3.15	%	—	%	—	%	—	%
Due after one year through five years	3.12		—		—		—
Due after five years through ten years	—		—		3.91		4.95
Due after ten years	—		—		4.68		—
Total	3.13	%	—	%	4.68	%	4.95	%

The following table discloses the Company’s available-for-sale debt securities that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 or more months:


	Less Than 12 Months				12 Months or Longer				Total
(in thousands)	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
September 30, 2024
U.S. Treasury securities	$	—	$	—	$	275,804	$	(2,396)	$	275,804	$	(2,396)
U.S. government agency securities	—		—		—		—		—		—
Residential mortgage-backed securities	458,752		(873)		1,404,200		(111,390)		1,862,952		(112,263)
CRT securities	—		—		12,002		(789)		12,002		(789)
Total	$	458,752	$	(873)	$	1,692,006	$	(114,575)	$	2,150,758	$	(115,448)
December 31, 2023
U.S. Treasury securities	$	—	$	—	$	636,473	$	(14,639)	$	636,473	$	(14,639)
U.S. government agency securities	—		—		106,592		(18,408)		106,592		(18,408)
Residential mortgage-backed securities	910,999		(19,751)		1,501,340		(292,691)		2,412,339		(312,442)
CRT securities	—		—		11,995		(1,641)		11,995		(1,641)
Total	$	910,999	$	(19,751)	$	2,256,400	$	(327,379)	$	3,167,399	$	(347,130)

At September 30, 2024, the Company had 43 available-for-sale debt securities in an unrealized loss position, comprised of 6 U.S. Treasury securities, 35 residential mortgage-backed securities and two CRT securities. The unrealized losses on the available-for-sale debt securities were the result of changes in market interest rates compared to the date the securities were acquired rather than the credit quality of the issuers or underlying loans. The Company does not currently intend to sell and based on current conditions it does not believe it is likely that the Company will be required to sell these available-for-sale debt securities before recovery of the amortized cost of such securities in an unrealized loss position and has therefore recorded the unrealized losses related to this portfolio in accumulated other comprehensive income/(loss), net (“AOCI”). Held-to-maturity securities consist of government guaranteed securities for which no loss is expected. At September 30, 2024 and December 31, 2023, no allowance for credit losses was established for available-for-sale or held-to-maturity debt securities.

Equity securities consist of investments that qualify for consideration under the regulations implementing the Community Reinvestment Act and investments in exchange traded funds. The following is a summary of unrealized and realized gains/(losses) recognized on equity securities included in other non-interest income on the consolidated statements of income and other comprehensive income:



	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2024		2023		2024		2023
Net gains/(losses) recognized during the period	$	2,752	$	(1,262)	$	6,727	$	934
Less: Realized net gains/(losses) recognized on securities sold	482		(70)		853		(676)
Unrealized net gains/(losses) recognized on securities still held	$	2,270	$	(1,192)	$	5,874	$	1,610