
(In thousands)	March 31, 2020		December 31, 2019
Available for sale debt securities	$	8,678,586	$	8,571,626
Trading debt securities	24,291		28,161
Equity securities:
Readily determinable fair value	2,633		2,929
No readily determinable fair value	1,405		1,280
Other:
Federal Reserve Bank stock	33,915		33,770
Federal Home Loan Bank stock	40,000		10,000
Private equity investments	81,159		94,122
Total investment securities⁽¹⁾	$	8,861,989	$	8,741,888

The Company has elected to measure equity securities with no readily determinable fair value at cost minus impairment, if any, plus or minus changes resulting from observable price changes for the identical or similar investment of the same issuer. This portfolio includes the Company's holdings of Visa Class B shares, which have a carrying value of zero, as there have not been observable price changes in orderly transactions for identical or similar investments of the same issuer. During the period, the Company did not record any impairment or other adjustments to the carrying amount of these equity securities without a readily determinable fair value.

Other investment securities include Federal Reserve Bank (FRB) stock, Federal Home Loan Bank (FHLB) stock, and investments in portfolio concerns held by the Company's private equity subsidiaries. FRB stock and FHLB stock are held for debt and regulatory purposes. Investment in FRB stock is based on the capital structure of the investing bank, and investment in FHLB stock is tied to the level of borrowings from the FHLB. These holdings are carried at cost. The private equity investments, in the absence of readily ascertainable market values, are carried at estimated fair value.

The majority of the Company’s investment portfolio is comprised of available for sale debt securities, which are carried at fair value with changes in fair value reported in accumulated other comprehensive income (AOCI). A summary of the available for sale debt securities by maturity groupings as of March 31, 2020 is shown below. The investment portfolio includes agency mortgage-backed securities, which are guaranteed by agencies such as the FHLMC, FNMA, and GNMA, in addition to non-agency mortgage-backed securities, which have no guarantee but are collateralized by commercial and residential mortgages.

Also included are certain other asset-backed securities, which are primarily collateralized by credit cards, automobiles, student loans, and commercial loans. These securities differ from traditional debt securities primarily in that they may have uncertain maturity dates and are priced based on estimated prepayment rates on the underlying collateral.


(In thousands)	Amortized Cost		Fair Value
U.S. government and federal agency obligations:
Within 1 year	$	86,714	$	86,079
After 1 but within 5 years	487,114		517,959
After 5 but within 10 years	225,372		236,409

Total U.S. government and federal agency obligations	799,200		840,447
Government-sponsored enterprise obligations:
Within 1 year	70,167		70,749


After 10 years	37,674		42,121
Total government-sponsored enterprise obligations	107,841		112,870
State and municipal obligations:
Within 1 year	55,673		55,911
After 1 but within 5 years	757,906		778,801
After 5 but within 10 years	366,186		380,949
After 10 years	67,856		67,407
Total state and municipal obligations	1,247,621		1,283,068
Mortgage and asset-backed securities:
Agency mortgage-backed securities	4,011,631		4,168,421
Non-agency mortgage-backed securities	708,554		717,008
Asset-backed securities	1,243,235		1,232,292
Total mortgage and asset-backed securities	5,963,420		6,117,721
Other debt securities:
Within 1 year	41,966		41,789
After 1 but within 5 years	212,864		215,466
After 5 but within 10 years	61,691		64,123
After 10 years	2,992		3,102
Total other debt securities	319,513		324,480
Total available for sale debt securities	$	8,437,595	$	8,678,586

Investments in U.S. government and federal agency obligations include U.S. Treasury inflation-protected securities, which totaled $433.6 million, at fair value, at March 31, 2020. Interest paid on these securities increases with inflation and decreases with deflation, as measured by the Consumer Price Index. Included in state and municipal obligations are $8.4 million, at fair value, of auction rate securities, which were purchased from bank customers in 2008. Interest on these bonds is currently being paid at the maximum failed auction rates.

As described in Note 1, the Company adopted ASU 2016-13, Measurement of Credit Losses on Financial Instruments, on January 1, 2020. The adoption of ASU 2016-13 had no impact to the Company's available for sale securities reported in its consolidated financial statements at January 1, 2020. For the three months ended March 31, 2020, the Company did not recognize a credit loss expense on any available for sale debt securities.

The Company’s impairment policy requires a review of all securities for which fair value is less than amortized cost. Special emphasis is placed on securities whose credit rating has fallen below Baa3 (Moody's) or BBB- (Standard & Poor's), whose fair values have fallen more than 20% below purchase price, or who have been identified based on management’s judgment. These securities are placed on a watch list and cash flow analyses are prepared on an individual security basis. Inputs to these models include factors such as cash flow projections, contractual payments required, delinquency rates, credit support from other tranches, prepayment speeds, collateral loss severity rates (including loan to values), and various other information related to the underlying collateral. Stress tests are performed at varying levels of delinquency rates, prepayment speeds and loss severities in order to gauge probable ranges of credit loss. At March 31, 2020, the fair value of securities on this watch list was $47.2 million compared to $51.6 million at December 31, 2019.

The Company's model for establishing its allowance for credit losses uses cash flows projected to be received over the estimated life of the securities, discounted to present value, and compared to the current amortized cost bases of the securities. As of March 31, 2020, the Company did not identify any securities for which a credit loss exists. Significant inputs to the cash flow models used at March 31, 2020 to quantify credit losses included the following:

The table below summarizes debt securities available for sale in an unrealized loss position for which an allowance for credit losses has not been recorded at March 31, 2020. Unrealized losses on these available for sale securities have not been recognized into income because the issuers' bonds are of investment grade quality (rated Baa3, BBB- or higher), their fair values have not fallen more than 20% below purchase price, and they have not been identified by management as a security needing a more detailed review. Additionally, management does not intend to sell the securities, and it is likely that management will not be required to sell the securities prior to their anticipated recovery. The cash flow analyses prepared for securities included on the watch list discussed above did not identify any instances where the present value of expected cash flows were less than the amortized cost basis of the security.

The following table summarizes debt securities available for sale in an unrealized loss position for which an allowance for credit losses has not been recorded at March 31, 2020, aggregated by major security type and length of impairment period.


	Less than 12 months						12 months or longer						Total
(In thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
March 31, 2020
U.S. government and federal agency obligations	$	89,112	$	949	$	—	$	—	$	89,112	$	949

State and municipal obligations	62,881		2,844		—		—		62,881		2,844
Mortgage and asset-backed securities:
Agency mortgage-backed securities	53,489		1,572		91		—		53,580		1,572
Non-agency mortgage-backed securities	288,712		2,662		52,529		515		341,241		3,177
Asset-backed securities	530,321		12,879		181,841		9,024		712,162		21,903
Total mortgage and asset-backed securities	872,522		17,113		234,461		9,539		1,106,983		26,652
Other debt securities	98,289		912		—		—		98,289		912
Total	$	1,122,804	$	21,818	$	234,461	$	9,539	$	1,357,265	$	31,357


	Less than 12 months						12 months or longer						Total
(In thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
December 31, 2019
U.S. government and federal agency obligations	$	31,787	$	21	$	25,405	$	21	$	57,192	$	42
Government-sponsored enterprise obligations	6,155		187		—		—		6,155		187
State and municipal obligations	6,700		31		1,554		1		8,254		32
Mortgage and asset-backed securities:
Agency mortgage-backed securities	652,352		5,306		147,653		867		800,005		6,173
Non-agency mortgage-backed securities	102,931		254		189,747		451		292,678		705
Asset-backed securities	330,876		3,610		152,461		2,108		483,337		5,718
Total mortgage and asset-backed securities	1,086,159		9,170		489,861		3,426		1,576,020		12,596
Other debt securities	5,496		4		997		3		6,493		7
Total	$	1,136,297	$	9,413	$	517,817	$	3,451	$	1,654,114	$	12,864

The entire available for sale debt portfolio included $1.4 billion of securities that were in a loss position at March 31, 2020, compared to $1.7 billion at December 31, 2019. The total amount of unrealized loss on these securities was $31.4 million at

For debt securities classified as available for sale, the following table shows the amortized cost, fair value, and allowance for credit losses of securities available for sale at March 31, 2020 and the corresponding amounts of gross unrealized gains and losses (pre-tax) in AOCI, by security type.


(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Allowance for Credit Losses		Fair Value
March 31, 2020
U.S. government and federal agency obligations	$	799,200	$	42,196	$	(949)	$	—	$	840,447
Government-sponsored enterprise obligations	107,841		5,029		—		—		112,870
State and municipal obligations	1,247,621		38,291		(2,844)		—		1,283,068
Mortgage and asset-backed securities:
Agency mortgage-backed securities	4,011,631		158,362		(1,572)		—		4,168,421
Non-agency mortgage-backed securities	708,554		11,631		(3,177)		—		717,008
Asset-backed securities	1,243,235		10,960		(21,903)		—		1,232,292
Total mortgage and asset-backed securities	5,963,420		180,953		(26,652)		—		6,117,721
Other debt securities	319,513		5,879		(912)		—		324,480
Total	$	8,437,595	$	272,348	$	(31,357)	$	—	$	8,678,586

For debt securities classified as available for sale, the following table shows the amortized cost and fair value of securities available-for-sale at December 31, 2019 and the corresponding amounts of gross unrealized gains and losses (pre-tax) in AOCI, by security type.


(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
December 31, 2019
U.S. government and federal agency obligations	$	827,861	$	23,957	$	(42)	$	851,776
Government-sponsored enterprise obligations	138,734		730		(187)		139,277
State and municipal obligations	1,225,532		42,427		(32)		1,267,927
Mortgage and asset-backed securities:
Agency mortgage-backed securities	3,893,247		50,890		(6,173)		3,937,964
Non-agency mortgage-backed securities	796,451		14,036		(705)		809,782
Asset-backed securities	1,228,151		11,056		(5,718)		1,233,489
Total mortgage and asset-backed securities	5,917,849		75,982		(12,596)		5,981,235
Other debt securities	325,555		5,863		(7)		331,411
Total	$	8,435,531	$	148,959	$	(12,864)	$	8,571,626


	For the Three Months Ended March 31
(In thousands)	2020		2019
Proceeds from sales of securities:
Available for sale debt securities	$	—	$	150,756
Equity securities	2		—

Total proceeds	$	2	$	150,756

Investment securities gains (losses), net:
Available for sale debt securities:

Gains realized on sales	$	—	$	1,386
Losses realized on sales	—		(692)

Equity securities:

Gains realized on sales	2		—

Fair value adjustments, net	(295)		223
Other:


Fair value adjustments, net	(13,008)		(1,842)
Total investment securities losses, net	$	(13,301)	$	(925)

Net gains and losses on investment securities for the three months ended March 31, 2020 included net losses in fair value of $295 thousand and $13.0 million on equity securities and private equity investments, respectively, due to fair value adjustments.

At March 31, 2020, securities totaling $3.9 billion in fair value were pledged to secure public fund deposits, securities sold under agreements to repurchase, trust funds, and borrowings at the FRB and FHLB. Securities pledged under agreements pursuant to which the collateral may be sold or re-pledged by the secured parties approximated $209.3 million, while the remaining securities were pledged under agreements pursuant to which the secured parties may not sell or re-pledge the collateral. Except for obligations of various government-sponsored enterprises such as FNMA, FHLB and FHLMC, no investment in a single issuer exceeded 10% of stockholders’ equity.