
	June 30, 2021
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value
Investment securities available-for-sale:
U.S. Treasury	$	109,847	$	2,008	$	(47)	$	111,808
Agency	554,342		6,335		(5,510)		555,167
Corporate	355,101		5,957		(2,676)		358,382
Municipal bonds	1,348,346		36,296		(5,169)		1,379,473
Collateralized mortgage obligations	617,596		287		(3,145)		614,738
Mortgage-backed securities	1,465,117		11,216		(8,454)		1,467,879
Total investment securities available-for-sale	4,450,349		62,099		(25,001)		4,487,447
Investment securities held-to-maturity:
Mortgage-backed securities	17,378		887		—		18,265
Other	1,555		—		—		1,555
Total investment securities held-to-maturity	18,933		887		—		19,820
Total investment securities	$	4,469,282	$	62,986	$	(25,001)	$	4,507,267


	December 31, 2020
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value
Investment securities available-for-sale:
U.S. Treasury	$	30,153	$	2,380	$	—	$	32,533
Agency	666,702		24,292		(608)		690,386
Corporate	412,223		3,591		(506)		415,308
Municipal bonds	1,412,012		37,260		(3,253)		1,446,019
Collateralized mortgage obligations	513,259		819		(712)		513,366
Mortgage-backed securities	812,384		21,662		(543)		833,503
Total investment securities available-for-sale	3,846,733		90,004		(5,622)		3,931,115
Investment securities held-to-maturity:
Mortgage-backed securities	22,124		1,281		—		23,405
Other	1,608		—		—		1,608
Total investment securities held-to-maturity	23,732		1,281		—		25,013
Total investment securities	$	3,870,465	$	91,285	$	(5,622)	$	3,956,128

Unrealized gains and losses on investment securities available-for-sale are recognized in stockholders’ equity as accumulated other comprehensive income or loss. At June 30, 2021, the Company had accumulated other comprehensive income of $37.1 million, or $26.5 million net of tax, compared to an accumulated other comprehensive income of $84.4 million, or $60.3 million net of tax, at December 31, 2020.


	June 30, 2021
	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
Investment securities available-for-sale:
U.S. Treasury	2	$	38,568	$	(47)	—	$	—	$	—	2	$	38,568	$	(47)
Agency	24	358,145		(5,244)		9	9,355		(266)		33	367,500		(5,510)
Corporate	11	91,496		(2,676)		—	—		—		11	91,496		(2,676)
Municipal bonds	68	375,132		(5,169)		—	—		—		68	375,132		(5,169)
Collateralized mortgage obligations	35	373,224		(3,145)		1	351		—		36	373,575		(3,145)
Mortgage-backed securities.	68	838,125		(8,454)		—	—		—		68	838,125		(8,454)
Total investment securities available-for-sale	208	$	2,074,690	$	(24,735)	10	$	9,706	$	(266)	218	$	2,084,396	$	(25,001)


	December 31, 2020
	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
Investment securities available-for-sale:

Agency	4	$	74,194	$	(307)	9	$	10,434	$	(301)	13	$	84,628	$	(608)
Corporate	9	71,226		(506)		—	—		—		9	71,226		(506)
Municipal bonds	56	312,894		(3,253)		—	—		—		56	312,894		(3,253)
Collateralized mortgage obligations	21	215,603		(710)		1	431		(2)		22	216,034		(712)
Mortgage-backed securities	16	139,071		(543)		—	—		—		16	139,071		(543)
Total investment securities available-for-sale	106	$	812,988	$	(5,319)	10	$	10,865	$	(303)	116	$	823,853	$	(5,622)

The Company reviews individual securities classified as available-for-sale to determine whether a decline in fair value below the amortized cost basis is deemed credit related or due to other factors such as changes in interest rates and general market conditions. An ACL on available-for-sale investment securities is recorded when the fair value of the investment is below its amortized cost and the decline in fair value has been deemed to be credit related through the Company’s qualitative assessment. Non-credit related declines in fair value of available-for-sale 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 income, net of tax. In the event the Company is required to sell or has the intent to sell an available-for-sale 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.

Credit losses on held-to-maturity investment securities are recorded at the time of purchase or acquisition and when the Company has designated securities as held-to-maturity. Credit losses on held-to-maturity investment securities are representative of current expected credit losses that may be incurred over the life of the investment.

The Company determines credit losses on both available-for-sale and held-to-maturity 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 available-for-sale 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.

During the second quarter of 2020, the Company acquired $829.9 million of available-for-sale securities in connection with the acquisition of Opus. Such securities were evaluated and it was determined that there were no investment securities classified as purchase credit deteriorated upon acquisition and, as a result, no allowance for credit losses was recorded.

The Company has no ACL for held-to maturity investment securities as of June 30, 2021 and December 31, 2020 because the likelihood of non-repayment is remote. The Company has no ACL for available-for-sale or investment securities June 30, 2021 and December 31, 2020. As of June 30, 2021, the Company has not recorded credit losses on certain available-for-sale securities that were in an unrealized loss position due to the high quality of the investments, with investment grade ratings, and many of them are issued by U.S. government agencies. Additionally, the Company continues to receive contractual principal and interest payments in a timely manner. The Company performed a qualitative assessment of these investments as of June 30, 2021, and does not believe the declines in fair value are credit related. There was no provision for credit losses recognized for available-for-sale or held-to-maturity investment securities investment securities during the three months ended June 30, 2021, March 31, 2021, and June 30, 2020, and the six months ended June 30, 2021 and June 30, 2020.

At June 30, 2021 and December 31, 2020, there were no available-for-sale or held-to-maturity securities in nonaccrual status. All securities in the portfolio were current with their contractual principal and interest payments. At June 30, 2021 and December 31, 2020, there were no securities purchased with deterioration in credit quality since their origination. At June 30, 2021 and December 31, 2020, there were no collateral dependent available-for-sale or held-to-maturity securities.


	Vintage
(Dollars in thousands)	2021		2020		2019		2018		2017		Prior		Total
Investment securities available-for-sale:
U.S. Treasury
Aaa - Aa3	$	33,148	$	26,266	$	20,481	$	21,408	$	10,505	$	—	$	111,808


Agency
Aaa - Aa3	9,572		349,992		55,601		83,752		—		56,250		555,167


Corporate debt

A1 - A3	—		58,502		—		—		—		60,573		119,075
Baa1 - Baa3	36,553		100,494		70,721		—		17,925		13,614		239,307
Municipal bonds
Aaa - Aa3	40,975		907,667		297,852		32,830		60,376		36,124		1,375,824
A1 - A3	—		—		—		—		—		2,309		2,309
Baa1 - Baa3	—		—		—		—		—		1,340		1,340
Collateralized mortgage obligations
Aaa - Aa3	142,912		232,492		91,915		20,786		14,443		112,190		614,738


Mortgage-backed securities
Aaa - Aa3	834,439		437,746		96,261		12,600		40,338		46,495		1,467,879


Total investment securities available-for-sale	1,097,599		2,113,159		632,831		171,376		143,587		328,895		4,487,447
Investment securities held-to-maturity:
Mortgage-backed securities
Aaa - Aa3	—		—		—		5,029		4,481		7,868		17,378


Other


Baa1 - Baa3	—		—		—		608		—		947		1,555
Total investment securities held-to-maturity	—		—		—		5,637		4,481		8,815		18,933
Total investment securities	$	1,097,599	$	2,113,159	$	632,831	$	177,013	$	148,068	$	337,710	$	4,506,380

During the three months ended June 30, 2021, March 31, 2021, and June 30, 2020, the Company recognized gross gains on sales of available-for-sale securities in the amount of $10.0 million, $4.2 million, and $1.3 million, respectively. During the three months ended June 30, 2021, March 31, 2021, and June 30, 2020, the Company recognized gross losses on sales of available-for-sale securities in the amount of $5.0 million, $191,000, and $1.3 million, respectively. The Company had net proceeds from the sales of available-for-sale securities of $285.3 million, $179.4 million, and $191.1 million, of which $6.5 million were receivables on unsettled securities sales, during the three months ended June 30, 2021, March 31, 2021, and June 30, 2020, respectively.

During the six months ended June 30, 2021 and 2020, the Company recognized gross gains on sales of available-for-sale securities in the amount of $14.3 million and $9.2 million, respectively. During the six months ended June 30, 2021 and 2020, the Company recognized gross losses on the sales of available-for sale securities in the amount of $5.1 million and $1.5 million, respectively. The Company had net proceeds from the sales of available-for-sale securities of $464.7 million and $346.4 million, of which $6.5 million were receivables on unsettled security sales, during the six months ended June 30, 2021 and 2020, respectively.


	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
Investment securities available-for-sale:
U.S. Treasury	$	—	$	—	$	30,135	$	31,913	$	79,712	$	79,895	$	—	$	—	$	109,847	$	111,808
Agency	—		—		312,054		314,952		184,783		184,414		57,505		55,801		554,342		555,167
Corporate	54,024		54,074		9,670		9,714		291,407		294,594		—		—		355,101		358,382
Municipal bonds	12,830		12,830		4,619		4,918		77,533		80,607		1,253,364		1,281,118		1,348,346		1,379,473
Collateralized mortgage obligations	—		—		26,394		26,357		229,519		226,997		361,683		361,384		617,596		614,738
Mortgage-backed securities	—		—		2,121		2,252		479,885		486,001		983,111		979,626		1,465,117		1,467,879
Total investment securities available-for-sale	66,854		66,904		384,993		390,106		1,342,839		1,352,508		2,655,663		2,677,929		4,450,349		4,487,447
Investment securities held-to-maturity:
Mortgage-backed securities	—		—		—		—		—		—		17,378		18,265		17,378		18,265
Other	—		—		—		—		—		—		1,555		1,555		1,555		1,555
Total investment securities held-to-maturity	—		—		—		—		—		—		18,933		19,820		18,933		19,820
Total investment securities	$	66,854	$	66,904	$	384,993	$	390,106	$	1,342,839	$	1,352,508	$	2,674,596	$	2,697,749	$	4,469,282	$	4,507,267

The Company’s equity securities primarily consist of FHLB and Federal Reserve Bank of San Francisco (“FRB”) stock, which are considered restricted securities and held as a condition of membership of the FHLB and the Board of Governors of the Federal Reserve System. These equity securities without readily determinable fair values are carried at cost less impairment. At June 30, 2021, the Company had $17.3 million in FHLB stock, $74.4 million in FRB stock, and $26.3 million in other stock, all carried at cost. During the three months ended June 30, 2021 and March 31, 2021, the FHLB did not repurchase any of the Company’s excess FHLB stock through its stock repurchase program. During the three months ended June 30, 2020, the FHLB repurchased $17.3 million of the company’s excess FHLB stock through its stock repurchase program.