4. Investment securities:

The amortized cost and fair value of investment securities aggregated by investment category at September 30, 2015 and December 31, 2014 are summarized as follows:


			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
September 30, 2015	Cost		Gains		Losses		Value
Available-for-sale:
U.S. Treasury securities	$	15,915	$	152		—	$	16,067
U.S. Government-sponsored enterprises		79,077		547	$	1		79,623
State and municipals:
Taxable		15,886		864		19		16,731
Tax-exempt		113,198		3,913		302		116,809
Mortgage-backed securities:
U.S. Government agencies		34,027		198		31		34,194
U.S. Government-sponsored enterprises		36,282		235		109		36,408
Total	$	294,385	$	5,909	$	462	$	299,832
Held-to-maturity:
Tax-exempt state and municipals	$	7,369	$	125	$	50	$	7,444
Mortgage-backed securities:
U.S. Government agencies		88		1		—		89
U.S. Government-sponsored enterprises		5,650		399		—		6,049
Total	$	13,107	$	525	$	50	$	13,582


			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
December 31, 2014	Cost		Gains		Losses		Value
Available-for-sale:
U.S. Treasury securities	$	48,393	$	157			$	48,550
U.S. Government-sponsored enterprises		95,990		337	$	82		96,245
State and municipals:
Taxable		16,490		943		26		17,407
Tax-exempt		87,954		4,971		24		92,901
Mortgage-backed securities:
U.S. Government agencies		37,511		132		167		37,476
U.S. Government-sponsored enterprises		46,956		277		226		47,007
Total	$	333,294	$	6,817	$	525	$	339,586
Held-to-maturity:
Tax-exempt state and municipals	$	7,370	$	105	$	38	$	7,437
Mortgage-backed securities:
U.S. Government agencies		100		2				102
U.S. Government-sponsored enterprises		7,195		481				7,676
Total		14,665	$	588	$	38	$	15,215

The maturity distribution of the fair value, which is the net carrying amount, of the debt securities classified as available-for-sale at September 30, 2015, is summarized as follows:


	Fair
September 30, 2015	Value
Within one year	$	33,161
After one but within five years		98,388
After five but within ten years		46,705
After ten years		50,976
		229,230
Mortgage-backed securities		70,602
Total	$	299,832

The maturity distribution of the amortized cost and fair value, of debt securities classified as held-to-maturity at September 30, 2015, is summarized as follows:


	Amortized		Fair
September 30, 2015	Cost		Value
Within one year
After one but within five years	$	503	$	515
After five but within ten years		—		—
After ten years		6,866		6,929
		7,369		7,444
Mortgage-backed securities		5,738		6,138
Total	$	13,107	$	13,582

Securities with a carrying value of $206,467 and $216,192 at September 30, 2015 and December 31, 2014, respectively, were pledged to secure public deposits and repurchase agreements as required or permitted by law.

Securities and short-term investment activities are conducted with a diverse group of government entities, corporations and state and local municipalities. The counterparty’s creditworthiness and type of collateral is evaluated on a case-by-case basis. At September 30, 2015 and December 31, 2014, there were no significant concentrations of credit risk from any one issuer, with the exception of U.S. Government agencies and sponsored enterprises that exceeded 10.0 percent of stockholders’ equity.

The fair value and gross unrealized losses of investment securities with unrealized losses for which an other-than-temporary impairment (“OTTI”) has not been recognized at September 30, 2015 and December 31, 2014, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position, are summarized as follows:


	Less Than 12 Months				12 Months or More				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
September 30, 2015	Value		Losses		Value		Losses		Value		Losses
U.S. Government-sponsored enterprises	$	3,006	$	1	$		$		$	3,006	$	1
State and municipals:
Taxable						546		19		546		19
Tax-exempt		41,034		325		789		27		41,823		352
Mortgage-backed securities:
U.S. Government agencies		877		7		5,119		24		5,996		31
U.S. Government-sponsored enterprises		9,819		20		6,682		89		16,501		109
Total	$	54,736	$	353	$	13,136	$	159	$	67,872	$	512


	Less Than 12 Months				12 Months or More				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
December 31, 2014	Value		Losses		Value		Losses		Value		Losses
U.S. Government-sponsored enterprises	$	21,228	$	33	$	7,954	$	49	$	29,182	$	82
State and municipals:
Taxable						544		26		544		26
Tax-exempt		4,702		23		2,423		39		7,125		62
Mortgage-backed securities:
U.S. Government agencies		20,148		167						20,148		167
U.S. Government-sponsored enterprises		22,870		226						22,870		226
Total	$	68,948	$	449	$	10,921	$	114	$	79,869	$	563

The Company had 97 investment securities, consisting of 76 tax-exempt state and municipal obligations, one taxable state and municipal obligation, one U.S. Government-sponsored enterprise security, and 19 mortgage-backed securities that were in unrealized loss positions at September 30, 2015. Of these securities, one taxable state and municipal obligation, eight mortgage-backed securities and three tax-exempt state and municipal securities were in a continuous unrealized loss position for twelve months or more. Management does not consider the unrealized losses on the debt securities, as a result of changes in interest rates, to be OTTI based on historical evidence that indicates the cost of these securities is recoverable within a reasonable period of time in relation to normal cyclical changes in the market rates of interest. Moreover, because there has been no material change in the credit quality of the issuers or other events or circumstances that may cause a significant adverse impact on the fair value of these securities, and management does not intend to sell these securities and it is unlikely that the Company will be required to sell these securities before recovery of their amortized cost basis, which may be maturity, the Company does not consider the unrealized losses to be OTTI at September 30, 2015. There was no OTTI recognized for the three or nine months ended September 30, 2015 and 2014.

The Company had 52 investment securities, consisting of 16 tax-exempt state and municipal obligations, one taxable state and municipal obligation, nine U.S. Government-sponsored enterprise securities and 26 mortgage-backed securities that were in unrealized loss positions at December 31, 2014. Of these securities, two U.S. Government-sponsored enterprise securities, four tax-exempt state and municipal securities, and one taxable state and municipal obligation were in a continuous unrealized loss position for twelve months or more.