The following tables set forth the amortized cost and estimated fair values of the Bank’s available-for-sale investment securities, and the corresponding amounts of unrealized gains and losses recognized on an after-tax basis in accumulated other comprehensive income (loss). There was no allowance for credit losses associated with the available-for-sale securities portfolio at March 31, 2020.



	March 31, 2020
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
(in thousands)	Cost		Gains		Losses		Value
State and municipals	$	365,652	$	10,318	$	(127)	$	375,843
Pass-through mortgage securities		56,555		2,088		—		58,643
Collateralized mortgage obligations		137,193		5,125		(23)		142,295
Corporate bonds		119,000		—		(16,318)		102,682
	$	678,400	$	17,531	$	(16,468)	$	679,463

	December 31, 2019
State and municipals	$	372,113	$	10,269	$	(239)	$	382,143
Pass-through mortgage securities		60,307		1,104		(39)		61,372
Collateralized mortgage obligations		136,211		2,247		(259)		138,199
Corporate bonds		119,000		—		(3,170)		115,830
	$	687,631	$	13,620	$	(3,707)	$	697,544

At March 31, 2020 and December 31, 2019, investment securities with a carrying value of $415,868,000 and $382,963,000, respectively, were pledged as collateral to secure public deposits, borrowed funds and derivative liabilities.

There were no holdings of any one issuer, other than the U.S. government and its agencies, in an amount greater than 10% of stockholders’ equity at March 31, 2020 and December 31, 2019.

Securities With Unrealized Losses. The following tables set forth securities with unrealized losses presented by the length of time the securities have been in a continuous unrealized loss position.



	March 31, 2020
	Less than				12 Months
	12 Months				or More				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Loss		Value		Loss		Value		Loss
State and municipals	$	7,765	$	(127)	$	—	$	—	$	7,765	$	(127)
Collateralized mortgage obligations		9,691		(23)		—		—		9,691		(23)
Corporate bonds		28,120		(3,880)		74,562		(12,438)		102,682		(16,318)
Total temporarily impaired	$	45,576	$	(4,030)	$	74,562	$	(12,438)	$	120,138	$	(16,468)

	December 31, 2019
State and municipals	$	6,662	$	(83)	$	5,084	$	(156)	$	11,746	$	(239)
Pass-through mortgage securities		5,287		(14)		4,084		(25)		9,371		(39)
Collateralized mortgage obligations		30,886		(259)		—		—		30,886		(259)
Corporate bonds		51,020		(980)		64,810		(2,190)		115,830		(3,170)
Total temporarily impaired	$	93,855	$	(1,336)	$	73,978	$	(2,371)	$	167,833	$	(3,707)

At March 31, 2020, approximately $7.8 million of state and municipal bonds had an unrealized loss of $127,000. Each of the state and municipal bonds are considered high investment grade and rated Aa2/AA- or higher. The decline in value is attributable to changes in interest rates and illiquidity and not credit quality. The issuers continue to make timely principal and interest payments on the bonds. The Bank does not have the intent to sell these securities and it is likely that it will not be required to sell the securities before their anticipated recovery. The fair value is expected to recover as the bonds approach maturity.

At March 31, 2020, one collateralized mortgage obligation of approximately $9.7 million had an unrealized loss of $23,000. This security was issued by a U.S. government-sponsored agency and is considered high investment grade. The decline in fair value is attributable to changes in interest rates and not credit quality. The issuer continues to make timely principal and interest payments on the bond. The Bank does not have the intent to sell this security and it is likely that it will not be required to sell the security before its anticipated recovery. The fair value is expected to recover as the bond approaches maturity.

At March 31, 2020, approximately $102.7 million of corporate bonds had an unrealized loss of $16.3 million. The corporate bonds represent senior unsecured debt obligations of six of the largest U.S. based financial institutions, including JPMorgan Chase, Bank of America, Citigroup, Goldman Sachs, Morgan Stanley, and Wells Fargo. Each of the corporate bonds have a stated maturity of ten years and mature in 2028. The bonds provide a fixed interest rate for a period of two years or three years and have a weighted average fixed rate yield of 5.14% at March 31, 2020, and then reset quarterly based on the ten year constant maturity swap rate. During the fourth quarters of 2020 and 2021, corporate bonds with current fair values totaling $74.6 million and $28.1 million, respectively, will begin to reprice on a quarterly basis.

Each of the financial institutions are considered upper medium investment grade and rated A3 or higher. The decline in fair value is attributable to a significant increase in credit spreads caused by the economic disruption from the COVID-19 pandemic, a decline in interest rates and the illiquid nature of the securities. The Bank does not have the intent to sell these securities and it is likely that it will not be required to sell the securities before their anticipated recovery. Each of these financial institutions have diversified revenue streams, are well capitalized and profitable and continue to make timely interest payments. Management evaluates the quarterly financial statements of each company to determine if full payment of principal and interest is in doubt and does not believe there is any impairment at March 31, 2020.

Sales of Available-for-Sale and Held-to-Maturity Securities. There were no sales of available-for-sale or held-to-maturity securities during the three months ended March 31, 2020 and 2019.

Maturities. The following table sets forth by maturity the amortized cost and fair value of the Bank’s state and municipal securities, and corporate bonds at March 31, 2020 based on the earlier of their stated maturity or, if applicable, their pre-refunded date. The remaining securities in the Bank’s investment securities portfolio are mortgage-backed securities, consisting of pass-through mortgage securities and collateralized mortgage obligations. Although these securities are expected to have substantial periodic repayments they are reflected in the table below in aggregate amounts.



(in thousands)	Amortized Cost		Fair Value
Within one year	$	8,598	$	8,629
After 1 through 5 years		72,675		73,963
After 5 through 10 years		263,976		251,385
After 10 years		139,403		144,548
Mortgage-backed securities		193,748		200,938
	$	678,400	$	679,463