Our investment securities portfolio consists of: (i) an available-for-sale securities portfolio and a held-to-maturity securities portfolio, both of which represent interest-earning investment securities, and (ii) a non-marketable and other equity securities portfolio, which primarily represents investments managed as part of our funds management business, investments in qualified affordable housing projects, as well as public equity securities held as a result of equity warrant assets exercised.


	March 31, 2021
(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Carrying Value
Available-for-sale securities, at fair value:
U.S. Treasury securities	$	4,244,175	$	195,444	$	(1,223)	$	4,438,396
U.S. agency debentures	230,375		1,155		(5,435)		226,095
Foreign government debt securities	23,454		—		(4)		23,450
Residential mortgage-backed securities:
Agency-issued mortgage-backed securities	12,663,089		85,210		(233,388)		12,514,911
Agency-issued collateralized mortgage obligations—fixed rate	7,471,566		19,567		(234,507)		7,256,626

Agency-issued commercial mortgage-backed securities	1,526,502		24,283		(23,792)		1,526,993

Total available-for-sale securities	$	26,159,161	$	325,659	$	(498,349)	$	25,986,471


	December 31, 2020
(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Carrying Value
Available-for-sale securities, at fair value:
U.S. Treasury securities	$	4,197,858	$	271,977	$	(107)	$	4,469,728
U.S. agency debentures	233,727		4,165		(585)		237,307
Foreign government debt securities	24,491		1		—		24,492
Residential mortgage-backed securities:
Agency-issued mortgage-backed securities	13,271,482		232,850		(651)		13,503,681
Agency-issued collateralized mortgage obligations—fixed rate	8,076,832		40,010		(10,278)		8,106,564

Agency-issued commercial mortgage-backed securities	4,440,506		133,527		(3,367)		4,570,666

Total available-for-sale securities	$	30,244,896	$	682,530	$	(14,988)	$	30,912,438

The following tables summarize our available-for-sale securities in an unrealized loss position for which an allowance for credit losses has not been recorded and summarized into categories of less than 12 months, or 12 months or longer, as of March 31, 2021 and December 31, 2020:


	March 31, 2021
	Less than 12 months				12 months or longer (1)				Total
(Dollars in thousands)	Fair Value of Investments		Unrealized Losses		Fair Value of Investments		Unrealized Losses		Fair Value of Investments		Unrealized Losses
Available-for-sale securities:
U.S. Treasury securities	$	301,607	$	(1,223)	$	—	$	—	$	301,607	$	(1,223)
U.S. agency debentures	128,228		(5,435)		—		—		128,228		(5,435)
Foreign government debt securities	23,450		(4)		—		—		23,450		(4)
Residential mortgage-backed securities:
Agency-issued mortgage-backed securities	9,608,598		(233,388)		—		—		9,608,598		(233,388)
Agency-issued collateralized mortgage obligations—fixed rate	5,248,844		(234,507)		—		—		5,248,844		(234,507)

Agency-issued commercial mortgage-backed securities	751,263		(23,792)		—		—		751,263		(23,792)
Total available-for-sale securities (1)	$	16,061,990	$	(498,349)	$	—	$	—	$	16,061,990	$	(498,349)

(1)As of March 31, 2021, we identified a total of 400 investments that were in unrealized loss positions with no investments in an unrealized loss position for a period of time greater than 12 months. Based on our analysis of the securities in an unrealized loss position as of March 31, 2021, the decline in value is unrelated to credit loss and is related to changes in market interest rates since purchase and therefore changes in value for securities are included in other comprehensive income. Market valuations and credit loss analyses on assets in the available-for-sale securities portfolio are reviewed and monitored on a quarterly basis. As of March 31, 2021, we do not intend to sell any of our securities in an unrealized loss position prior to recovery of our amortized cost basis, and it is more likely than not that we will not be required to sell any of our securities prior to recovery of our amortized cost basis. None of the investments in our available-for-sale securities portfolio were past due as of March 31, 2021.


	December 31, 2020
	Less than 12 months				12 months or longer (1)				Total
(Dollars in thousands)	Fair Value of Investments		Unrealized Losses		Fair Value of Investments		Unrealized Losses		Fair Value of Investments		Unrealized Losses
Available-for-sale securities:
U.S. Treasury securities	$	59,929	$	(107)	$	—	$	—	$	59,929	$	(107)
U.S. agency debentures	133,143		(585)		—		—		133,143		(585)

Residential mortgage-backed securities:
Agency-issued mortgage-backed securities	903,767		(651)		—		—		903,767		(651)
Agency-issued collateralized mortgage obligations—fixed rate	2,199,207		(10,278)		—		—		2,199,207		(10,278)

Agency-issued commercial mortgage-backed securities	989,389		(3,367)		—		—		989,389		(3,367)

Total available-for-sale securities (1)	$	4,285,435	$	(14,988)	$	—	$	—	$	4,285,435	$	(14,988)

(1)As of December 31, 2020, we identified a total of 93 investments that were in unrealized loss positions, of which no investments are in an unrealized loss position for a period of time greater than 12 months. None of the investments in our available-for-sale securities portfolio were past due as of December 31, 2020.

The following table summarizes the fixed income securities, carried at fair value, classified as available-for-sale as of March 31, 2021 by the remaining contractual principal maturities. For U.S. Treasury securities, U.S. agency debentures and foreign government debt securities, the expected maturity is the actual contractual maturity of the notes. Expected maturities for mortgage-backed securities may differ significantly from their contractual maturities because mortgage borrowers have the right to prepay outstanding loan obligations with or without penalties. Mortgage-backed securities classified as available-for-sale typically have original contractual maturities from 10 to 30 years whereas expected average lives of these securities tend to be significantly shorter and vary based upon structure and prepayments in lower interest rate environments.


	March 31, 2021
(Dollars in thousands)	Total		One Year or Less		After One Year to Five Years		After Five Years to Ten Years		After Ten Years
U.S. Treasury securities	$	4,438,396	$	40,481	$	3,844,128	$	553,787	$	—
U.S. agency debentures	226,095		—		—		226,095		—
Foreign government debt securities	23,450		23,450		—		—		—
Residential mortgage-backed securities:
Agency-issued mortgage-backed securities	12,514,911		—		—		—		12,514,911
Agency-issued collateralized mortgage obligations—fixed rate	7,256,626		—		—		—		7,256,626

Agency-issued commercial mortgage-backed securities	1,526,993		—		—		1,526,993		—
Total	$	25,986,471	$	63,931	$	3,844,128	$	2,306,875	$	19,771,537

During the first quarter of 2021, we re-designated certain securities from the classification of “available-for-sale” to “held-to-maturity." The securities re-designated consisted of agency-issued commercial mortgage-backed securities with a total carrying value of $2.9 billion at March 31, 2021. At the time of re-designation the securities included $8.7 million of pretax unrealized gains in other comprehensive income and are being amortized over the life of the securities in a manner consistent with the amortization of a premium or discount. Our decision to re-designate the securities was based on our ability and intent to hold these securities to maturity. Factors used in assessing the ability to hold these securities to maturity were future liquidity needs and sources of funding. Held-to-maturity securities are carried on the balance sheet at amortized cost and the changes in the value of these securities, other than an allowance for credit losses, are not reported on the financial statements.


	March 31, 2021
(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value		Allowance for Credit Losses
Held-to-maturity securities, at cost:
U.S. agency debentures (1)	$	404,571	$	11,618	$	—	$	416,189	$	—
Residential mortgage-backed securities:
Agency-issued mortgage-backed securities	23,525,681		184,691		(296,061)		23,414,311		—
Agency-issued collateralized mortgage obligations —fixed rate	2,425,024		23,807		(5,593)		2,443,238		—
Agency-issued collateralized mortgage obligations—variable rate	128,370		667		—		129,037		—
Agency-issued commercial mortgage-backed securities	10,075,165		81,135		(85,801)		10,070,499		—
Municipal bonds and notes	4,555,237		150,919		(43,935)		4,662,221		531
Corporate bonds	51,684		—		(444)		51,240		581
Total held-to-maturity securities	$	41,165,732	$	452,837	$	(431,834)	$	41,186,735	$	1,112


	December 31, 2020
(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value		Allowance for Credit Losses
Held-to-maturity securities, at amortized cost:
U.S. agency debentures (1)	$	402,265	$	18,961	$	—	$	421,226	$	—
Residential mortgage-backed securities:
Agency-issued mortgage-backed securities	7,739,763		240,121		(2,211)		7,977,673		—
Agency-issued collateralized mortgage obligations—fixed rate	1,735,451		23,227		(296)		1,758,382		—
Agency-issued collateralized mortgage obligations—variable rate	136,913		317		—		137,230		—
Agency-issued commercial mortgage-backed securities	2,942,959		123,846		—		3,066,805		—
Municipal bonds and notes	3,635,194		220,866		(505)		3,855,555		392
Total held-to-maturity securities	$	16,592,545	$	627,338	$	(3,012)	$	17,216,871	$	392


Three months ended March 31, 2021	Beginning Balance December 31, 2020		Provision for Credit Losses		Ending Balance March 31, 2021
(Dollars in thousands)
Municipal bonds and notes	$	392	$	139	$	531
Corporate bonds	—		581		581
Total allowance for credit losses	$	392	$	720	$	1,112


Three months ended March 31, 2020	Beginning Balance December 31, 2019		Day One Impact of Adopting ASC 326		Provision for Credit Losses		Ending Balance March 31, 2020
(Dollars in thousands)
Municipal bonds and notes	$	—	$	174	$	56	$	230
Total allowance for credit losses	$	—	$	174	$	56	$	230

Accrued interest receivable ("AIR") from HTM securities totaled $96.1 million at March 31, 2021 and $55.0 million at December 31, 2020 and is reported in "Accrued interest receivable and other assets" in our unaudited interim consolidated balance sheets.


(Dollars in thousands)	March 31, 2021		December 31, 2020
Municipal bonds and notes:
Aaa	$	2,519,992	$	2,070,311
Aa1	1,329,903		1,144,500
Aa2	568,423		420,383
Aa3	124,724		—
A1	12,195		—
Total municipal bonds and notes	$	4,555,237	$	3,635,194
Corporate bonds:


Aa2	$	27,583	$	—
Aa3	24,101		—
Total corporate bonds	$	51,684	$	—

The following table summarizes the remaining contractual principal maturities on fixed income investment securities classified as held-to-maturity as of March 31, 2021. For U.S. agency debentures, the expected maturity is the actual contractual maturity of the notes. Expected remaining maturities for certain U.S. agency debentures may occur earlier than their contractual maturities because the note issuers have the right to call outstanding amounts ahead of their contractual maturity. Expected maturities for mortgage-backed securities may differ significantly from their contractual maturities because mortgage borrowers have the right to prepay outstanding loan obligations with or without penalties. Mortgage-backed securities classified as held-to-maturity typically have original contractual maturities from 10 to 30 years whereas expected average lives of these securities tend to be significantly shorter and vary based upon structure and prepayments in lower interest rate environments.


	March 31, 2021
	Total				One Year or Less				After One Year to Five Years				After Five Years to Ten Years				After Ten Years
(Dollars in thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value
U.S. agency debentures	$	404,571	$	416,189	$	4,066	$	4,117	$	141,117	$	145,321	$	259,388	$	266,751	$	—	$	—
Residential mortgage-backed securities:
Agency-issued mortgage-backed securities	23,525,681		23,414,311		6,319		6,564		11,663		11,983		494,951		510,743		23,012,748		22,885,021
Agency-issued collateralized mortgage obligations—fixed rate	2,425,024		2,443,238		—		—		5,356		5,482		447,781		458,314		1,971,887		1,979,442
Agency-issued collateralized mortgage obligations—variable rate	128,370		129,037		—		—		—		—		—		—		128,370		129,037
Agency-issued commercial mortgage-backed securities	10,075,165		10,070,499		—		—		—		—		536,203		542,183		9,538,962		9,528,316
Municipal bonds and notes	4,555,237		4,662,221		48,536		49,209		130,482		136,075		756,078		795,055		3,620,141		3,681,882
Corporate bonds	51,684		51,240		—		—		—		—		51,684		51,240		—		—
Total	$	41,165,732	$	41,186,735	$	58,921	$	59,890	$	288,618	$	298,861	$	2,546,085	$	2,624,286	$	38,272,108	$	38,203,698


(Dollars in thousands)	March 31, 2021		December 31, 2020
Non-marketable and other equity securities:
Non-marketable securities (fair value accounting):
Consolidated venture capital and private equity fund investments (1)	$	96,016	$	88,937
Unconsolidated venture capital and private equity fund investments (2)	178,407		184,886
Other investments without a readily determinable fair value (3)	200,367		60,975
Other equity securities in public companies (fair value accounting) (4)	160,810		280,804
Non-marketable securities (equity method accounting) (5):
Venture capital and private equity fund investments	394,349		362,192
Debt funds	5,813		5,444
Other investments	205,002		202,809
Investments in qualified affordable housing projects, net (6)	616,997		616,188
Total non-marketable and other equity securities	$	1,857,761	$	1,802,235


	March 31, 2021				December 31, 2020
(Dollars in thousands)	Amount		Ownership %		Amount		Ownership %
Strategic Investors Fund, LP	$	5,165	12.6	%	$	4,850	12.6	%
Capital Preferred Return Fund, LP	48,572		20.0		49,574		20.0
Growth Partners, LP	42,279		33.0		34,513		33.0
Total consolidated venture capital and private equity fund investments	$	96,016			$	88,937

(2)The carrying value represents investments in 161 and 162 funds (primarily venture capital funds) at March 31, 2021 and December 31, 2020, respectively, where our ownership interest is typically less than 5% of the voting interests of each such fund and in which we do not have the ability to exercise significant influence over the partnerships operating activities and financial policies. We carry our unconsolidated venture capital and private equity fund investments at fair value based on the fund investments' net asset values per share as obtained from the general partners of the investments. For each fund investment, we adjust the net asset value per share for differences between our measurement date and the date of the fund investment’s net asset value by using the most recently available financial information from the investee general partner, for example December 31st for our March 31st consolidated financial statements, adjusted for any contributions paid, distributions received from the investment, and significant fund transactions or market events during the reporting period.

(3)These investments include direct equity investments in private companies. The carrying value is based on the price at which the investment was acquired plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments. We consider a range of factors when adjusting the fair value of these investments, including, but not limited to, the term and nature of the investment, local market conditions, values for comparable securities, current and projected operating performance, exit strategies, financing transactions subsequent to the acquisition of the investment and a discount for certain investments that have lock-up restrictions or other features that indicate a discount to fair value is warranted.


(Dollars in thousands)	Three months ended March 31, 2021		Cumulative Adjustments
Measurement alternative:
Carrying value at March 31, 2021	$	200,367
Carrying value adjustments:
Impairment	$	—	$	(947)
Upward changes for observable prices	13,762		17,121
Downward changes for observable prices	(456)		(4,327)

(4)Investments classified as other equity securities (fair value accounting) represent shares held in public companies as a result of exercising public equity warrant assets and direct equity investments in public companies held by our consolidated funds. Changes in equity securities measured at fair value are recognized through net income.


	March 31, 2021				December 31, 2020
(Dollars in thousands)	Amount		Ownership %		Amount		Ownership %
Venture capital and private equity fund investments:
Strategic Investors Fund II, LP	$	4,624	8.6	%	$	3,705	8.6	%
Strategic Investors Fund III, LP	21,281		5.9		16,110		5.9
Strategic Investors Fund IV, LP	29,681		5.0		25,169		5.0
Strategic Investors Fund V funds	60,992		Various		67,052		Various
CP II, LP (i)	8,954		5.1		7,887		5.1
Other venture capital and private equity fund investments	268,817		Various		242,269		Various
Total venture capital and private equity fund investments	$	394,349			$	362,192
Debt funds:
Gold Hill Capital 2008, LP (ii)	$	4,380	15.5	%	$	3,941	15.5	%
Other debt funds	1,433		Various		1,503		Various
Total debt funds	$	5,813			$	5,444
Other investments:
SPD Silicon Valley Bank Co., Ltd.	$	111,838	50.0	%	$	115,232	50.0	%
Other investments	93,164		Various		87,577		Various
Total other investments	$	205,002			$	202,809

(6)The following table presents the balances of our investments in qualified affordable housing projects and related unfunded commitments included as a component of “Other liabilities” on our consolidated balance sheets at March 31, 2021 and December 31, 2020:

The following table presents the net gains and losses on non-marketable and other equity securities for the three months ended March 31, 2021 and 2020 as recorded in the line item “Gains on investment securities, net," a component of noninterest income:


	Three months ended March 31,
(Dollars in thousands)	2021		2020
Net gains (losses) on non-marketable and other equity securities:
Non-marketable securities (fair value accounting):
Consolidated venture capital and private equity fund investments	$	17,211	$	3,113
Unconsolidated venture capital and private equity fund investments	12,510		1,252
Other investments without a readily determinable fair value	13,769		(2,943)
Other equity securities in public companies (fair value accounting)	77,561		(7,504)
Non-marketable securities (equity method accounting):
Venture capital and private equity fund investments	45,385		(8,046)
Debt funds	414		(362)
Other investments	228		(620)
Total net gains (losses) on non-marketable and other equity securities	$	167,078	$	(15,110)


Less: realized net gains (losses) on sales of non-marketable and other equity securities	69,775		(49)
Net gains (losses) on non-marketable and other equity securities still held	$	97,303	$	(15,061)