SECURITIES

Amortized cost and estimated fair value of securities available for sale at December 31, 2017 and 2016 are as follows (in thousands):



	2017				2016
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Obligations of U.S. Government and U.S. Government sponsored enterprises	$	15,492	$	15,491	$	17,300	$	17,455
Mortgage-backed securities, residential	224,939		219,909		253,156		245,866
Obligations of states and political subdivisions	52,928		53,132		38,843		38,740
Corporate bonds and notes	249		251		249		250
SBA loan pools	4,339		4,308		568		570
Corporate stocks	265		536		285		521
Total	$	298,212	$	293,627	$	310,401	$	303,402

Gross unrealized gains and losses on securities available for sale at December 31, 2017 and 2016, were as follows (in thousands):



	2017				2016
	Unrealized Gains		Unrealized Losses		Unrealized Gains		Unrealized Losses
Obligations of U.S. Government and U.S. Government sponsored enterprises	$	20	$	21	$	155	$	—
Mortgage-backed securities, residential	136		5,166		202		7,492
Obligations of states and political subdivisions	355		151		209		312
Corporate bonds and notes	2		—		1		—
SBA loan pools	1		32		3		1
Corporate stocks	271		—		236		—
Total	$	785	$	5,370	$	806	$	7,805

The amortized cost and estimated fair value of debt securities available for sale are shown below by contractual maturity. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately (in thousands):



	December 31, 2017
	Amortized Cost		Fair Value
Within one year	$	16,998	$	16,990
After one, but within five years	21,048		21,074
After five, but within ten years	12,700		12,746
After ten years	17,923		18,064
Mortgage-backed securities, residential	224,939		219,909
SBA loan pools	4,339		4,308
Total	$	297,947	$	293,091

Actual maturities may differ from contractual maturities above because issuers may have the right to call or prepay obligations with or without call or prepayment penalties.

The proceeds from sales and calls of securities resulting in gains or losses are listed below (in thousands):



	2017		2016			2015
Proceeds	$	5,576	$	40,413		$	72,718
Gross gains	$	109	$	989		$	410
Gross losses	$	—	$	(2	)	$	(38	)
Tax expense	$	41	$	373		$	142

Amortized cost and estimated fair value of securities held to maturity at December 31, 2017 and 2016 are as follows (in thousands):



	2017				2016
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Obligations of states and political subdivisions	$	1,946	$	1,946	$	3,725	$	3,931
Time deposits with other financial institutions	1,835		1,830		980		981
	$	3,781	$	3,776	$	4,705	$	4,912

Gross unrealized gains and losses on securities held to maturity at December 31, 2017 and 2016, were as follows (in thousands):



	2017				2016
	Unrealized Gains		Unrealized Losses		Unrealized Gains		Unrealized Losses
Obligations of states and political subdivisions	$	—	$	—	$	206	$	—
Time deposits with other financial institutions	—		5		1		—
Total	$	—	$	5	$	207	$	—

There were no sales of securities held to maturity in 2017 or 2016.

The contractual maturity of securities held to maturity is as follows at December 31, 2017 (in thousands):



	December 31, 2017
	Amortized Cost		Fair Value
Within one year	$	988	$	986
After one, but within five years	2,560		2,557
After five, but within ten years	233		233
After ten years	—		—
Total	$	3,781	$	3,776

The following table summarizes the investment securities available for sale with unrealized losses at December 31, 2017 and December 31, 2016 by aggregated major security type and length of time in a continuous unrealized position (in thousands):



	Less than 12 months				12 months or longer				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
2017	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Obligations of U.S. Government and U.S. Government sponsored enterprises	$	14,982	$	21	$	—	$	—	$	14,982	$	21
Mortgage-backed securities, residential	$	83,562	$	1,013	$	131,165	$	4,153	$	214,727	$	5,166
Obligations of states and political subdivisions	20,526		133		271		18		20,797		151
SBA loan pools	3,937		32		—		—		3,937		32
Total temporarily impaired securities	$	123,007	$	1,199	$	131,436	$	4,171	$	254,443	$	5,370



	Less than 12 months				12 months or longer				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
2016	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Mortgage-backed securities, residential	$	233,843	$	7,492	$	—	$	—	$	233,843	$	7,492
Obligations of states and political subdivisions	25,724		312		—		—		25,724		312
SBA loan pools	—		—		225		1		225		1
Total temporarily impaired securities	$	259,567	$	7,804	$	225	$	1	$	259,792	$	7,805

Other-Than-Temporary-Impairment

As of December 31, 2017, the majority of the Corporation’s unrealized losses in the investment securities portfolio related to mortgage-backed securities. At December 31, 2017, all of the unrealized losses related to mortgage-backed securities were issued by U.S. government sponsored entities, Fannie Mae and Freddie Mac. Because the decline in fair value is attributable to changes in interest rates and not credit quality, and because the Corporation does not have the intent to sell these securities and it is not likely that it will be required to sell these securities before their anticipated recovery, the Corporation does not consider these securities to be other-than-temporarily impaired at December 31, 2017.

The Corporation's unrealized losses on securities held to maturity related to certificates of deposits. At December 31, 2017, all of the unrealized losses related to certificates of deposit within other financial institutions and were under the FDIC insurance limit of $250,000. Because the decline in fair value is attributable to changes in interest rates and not credit quality, and because the Corporation does not have the intent to sell these securities and it is not likely that it will be required to see these securities before their anticipated recovery, the Corporation does not consider these securities to be other-than-temporarily impaired at December 31, 2017.

Pledged Securities

The fair value of securities pledged to secure public funds on deposit or for other purposes as required by law was $231.6 million at December 31, 2017 and $191.0 million at December 31, 2016.

The table below shows the securities pledged to secure securities sold under agreements to repurchase at December 31, 2017 and 2016 (in thousands):



	2017				2016
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Obligations of U.S. Government and U. S. Government sponsored enterprises	$	—	$	—	$	1,231	$	1,276
Mortgage-backed securities, residential	12,082		11,798		37,769		37,000
Total	$	12,082	$	11,798	$	39,000	$	38,276

Concentrations

There are no securities of a single issuer (other than securities of U.S. Government sponsored enterprises) that exceed 10% of shareholders' equity at December 31, 2017 or 2016.

Equity Method Investments

The Corporation has an equity investment in Cephas Capital Partners, L.P. This small business investment company was established for the purpose of providing financing to small businesses in market areas served by the Corporation, including minority-owned small businesses and those that are anticipated to create jobs for the low to moderate income levels in the targeted areas. As of both December 31, 2017 and 2016, these investments totaled $0.4 million, are included in other assets, and are accounted for under the equity method of accounting.