Investment Securities

The amortized cost, gross unrealized gains and losses and estimated fair values for available-for-sale and held-to-maturity securities by major security type at March 31, 2019 and December 31, 2018 were as follows (in thousands):



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Fair Value
March 31, 2019
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations & agencies	$	190,845	$	926	$	(1,044	)	$	190,727
Obligations of states and political subdivisions	188,572		2,996		(465		)	191,103
Mortgage-backed securities: GSE residential	312,159		1,399		(2,074		)	311,484
Other securities	2,278		26		—			2,304
Total available-for-sale	$	693,854	$	5,347	$	(3,583	)	$	695,618
Held-to-maturity:
U.S. Treasury securities and obligations of U.S. government corporations & agencies	$	69,462	$	11	$	(730	)	$	68,743

December 31, 2018
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations & agencies	$	201,380	$	504	$	(3,235	)	$	198,649
Obligations of states and political subdivisions	193,195		1,224		(1,840		)	192,579
Mortgage-backed securities: GSE residential	304,372		486		(6,186		)	298,672
Other securities	2,278		96		—			2,374
Total available-for-sale	$	701,225	$	2,310	$	(11,261	)	$	692,274
Held-to-maturity:
U.S. Treasury securities and obligations of U.S. government corporations & agencies	$	69,436	$	—	$	(1,527	)	$	67,909

Realized gains and losses resulting from sales of securities were as follows during the three months ended March 31, 2019 and 2018 (in thousands):



	Three months ended March 31,
	2019			2018
Gross gains	$	84		$	20
Gross losses	(30		)	—

The following table indicates the expected maturities of investment securities classified as available-for-sale presented at fair value, and held-to-maturity presented at amortized cost, at March 31, 2019 and the weighted average yield for each range of maturities (dollars in thousands):



	One year or less			After 1 through 5 years			After 5 through 10 years			After ten years			Total
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	148,125		$	42,602		$	—		$	—		$	190,727
Obligations of state and political subdivisions	26,862			85,494			77,798			949			191,103
Mortgage-backed securities: GSE residential	657			214,585			96,242			—			311,484
Other securities	—			2,014			—			290			2,304
Total available-for-sale investments	$	175,644		$	344,695		$	174,040		$	1,239		$	695,618
Weighted average yield	2.64		%	2.85		%	2.92		%	3.06		%	2.82		%
Full tax-equivalent yield	2.79		%	3.12		%	3.43		%	4.07		%	3.12		%
Held to Maturity:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	49,940		$	19,522		$	—		$	—		$	69,462
Weighted average yield	1.83		%	2.06		%	—		%	—		%	1.90		%
Full tax-equivalent yield	1.83		%	2.06		%	—		%	—		%	1.90		%

The weighted average yields are calculated on the basis of the amortized cost and effective yields weighted for the scheduled maturity of each security. Tax-equivalent yields have been calculated using a 21% tax rate. With the exception of obligations of the U.S. Treasury and other U.S. government agencies and corporations, there were no investment securities of any single issuer, the book value of which exceeded 10% of stockholders' equity at March 31, 2019.

Investment securities carried at approximately $574 million and $628 million at March 31, 2019 and December 31, 2018, respectively, were pledged to secure public deposits and repurchase agreements and for other purposes as permitted or required by law.

The following table presents the aging of gross unrealized losses and fair value by investment category as of March 31, 2019 and December 31, 2018 (in thousands):



	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
March 31, 2019
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	998	$	—		$	82,772	$	(1,044	)	$	83,770	$	(1,044	)
Obligations of states and political subdivisions	1,382		(3		)	30,225		(462		)	31,607		(465		)
Mortgage-backed securities: GSE residential	1,952		(5		)	199,536		(2,069		)	201,488		(2,074		)
Total	$	4,332	$	(8	)	$	312,533	$	(3,575	)	$	316,865	$	(3,583	)
Held-to-maturity:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	—	$	—		$	63,775	$	(730	)	$	63,775	$	(730	)
December 31, 2018
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	16,095	$	(148	)	$	105,549	$	(3,087	)	$	121,644	$	(3,235	)
Obligations of states and political subdivisions	38,782		(450		)	42,741		(1,390		)	81,523		(1,840		)
Mortgage-backed securities: GSE residential	81,435		(1,150		)	171,321		(5,036		)	252,756		(6,186		)
Total	$	136,312	$	(1,748	)	$	319,611	$	(9,513	)	$	455,923	$	(11,261	)
Held-to-maturity:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	19,683	$	(147	)	$	48,226	$	(1,380	)	$	67,909	$	(1,527	)

U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies. At March 31, 2019 there were nineteen available-for sale U.S. Treasury securities and obligations of U.S. government corporations and agencies with a fair value of $82,772,000 and unrealized losses of $1,044,000 in a continuous unrealized loss position for twelve months or more. At December 31, 2018 , there were twenty-three available-for sale U.S. Treasury securities and obligations of U.S. government corporations and agencies with a fair value of $105,549,000 and unrealized losses of $3,087,000 in a continuous unrealized loss position for twelve months or more. At March 31, 2019 there were thirteen held-to-maturity U.S. Treasury securities and obligations of U.S. government corporations and agencies with a fair value of $63,775,000 and unrealized losses of $730,000 in a continuous unrealized loss position for twelve months or more. At December 31, 2018 there were nine held-to-maturity U.S. Treasury securities and obligations of U.S. government corporations and agencies with a fair value of $48,226,000 and unrealized losses of $1,380,000 in a continuous unrealized loss position for twelve months or more.

Obligations of states and political subdivisions. At March 31, 2019 there were sixty-one obligations of states and political subdivisions with a fair value of $30,225,000 and unrealized losses of $462,000 in a continuous loss position for twelve months or more. At December 31, 2018, there were eighty-four obligations of states and political subdivisions with a fair value of $42,741,000 and unrealized losses of $1,390,000 in a continuous unrealized loss position for twelve months or more.

Mortgage-backed Securities: GSE Residential. At March 31, 2019 there were seventy-seven mortgage-backed securities with a fair value of $199,536,000 and unrealized losses of $2,069,000 in a continuous unrealized loss position for twelve months or more. At December 31, 2018, there were sixty-nine mortgage-backed securities with a fair value of $171,321,000 and unrealized losses of $5,036,000 in a continuous unrealized loss position for twelve months or more.

Other securities. At March 31, 2019 and December 31, 2018, there were no other securities in a continuous unrealized loss position for twelve months or more.

The Company does not believe any other individual unrealized loss as of March 31, 2019 represents other than temporary impairment ("OTTI"). However, given the continued disruption in the financial markets, the Company may be required to recognize OTTI losses in future periods with respect to its available for sale investment securities portfolio. The amount and timing of any additional OTTI will depend on the decline in the underlying cash flows of the securities. Should the impairment of any of these securities become other-than-temporary, the cost basis of the investment will be reduced and the resulting loss recognized in the period the other-than-temporary impairment is identified.

Other-than-temporary Impairment. Upon acquisition of a security, the Company determines whether it is within the scope of the accounting guidance for investments in debt and equity securities or whether it must be evaluated for impairment under the accounting guidance for beneficial interests in securitized financial assets.

If the Company determines that a given pooled trust preferred security position will be subject to a write-down or loss, the Company records the expected credit loss as a charge to earnings.

Credit Losses Recognized on Investments. The following table provides information about the trust preferred security for which only a credit loss was recognized in income and other losses were recorded in other comprehensive income (loss) for the three months ended March 31, 2019 and 2018 (in thousands).



	Accumulated Credit Losses
	March 31, 2019		March 31, 2018
Credit losses on trust preferred securities held
Beginning of period	$	—	$	1,111
Additions related to OTTI losses not previously recognized	—		—
Reductions due to sales / (recoveries)	—		—
Reductions due to change in intent or likelihood of sale	—		—
Additions related to increases in previously recognized OTTI losses	—		—
Reductions due to increases in expected cash flows	—		—
End of period	$	—	$	1,111

On May 29, 2018 the Company sold its trust preferred security. This sale resulted in recovery of all of the book value of the security. The net proceeds exceeded the aggregate book value of these securities by approximately $846,000 and this amount was recorded as a security gain during the second quarter of 2018.