Investment Securities

The following tables summarize the amortized cost and estimated fair value of investment securities at December 31, 2015 and 2014:



	Amortized		Unrealized		Unrealized			Fair Value
As of December 31, 2015	Cost		Gains		Losses			(Estimated)
Securities available for sale
Mortgage-backed securities	$	194,563,000	$	1,509,000	$	(962,000	)	$	195,110,000
State and political subdivisions	23,367,000		1,201,000		(62,000		)	24,506,000
Other equity securities	3,381,000		48,000		(6,000		)	3,423,000
	$	221,311,000	$	2,758,000	$	(1,030,000	)	$	223,039,000
Securities to be held to maturity
U.S. Government-sponsored agencies	$	71,000,000	$	40,000	$	(2,284,000	)	$	68,756,000
Mortgage-backed securities	42,193,000		1,305,000		(136,000		)	43,362,000
State and political subdivisions	122,530,000		4,200,000		(25,000		)	126,705,000
Corporate securities	4,300,000		—		—			4,300,000
	$	240,023,000	$	5,545,000	$	(2,445,000	)	$	243,123,000
Restricted equity securities
Federal Home Loan Bank Stock	$	13,220,000	$	—	$	—		$	13,220,000
Federal Reserve Bank Stock	1,037,000		—		—			1,037,000
	$	14,257,000	$	—	$	—		$	14,257,000



	Amortized		Unrealized		Unrealized			Fair Value
As of December 31, 2014	Cost		Gains		Losses			(Estimated)
Securities available for sale
Mortgage-backed securities	$	149,796,000	$	2,637,000	$	(578,000	)	$	151,855,000
State and political subdivisions	29,094,000		1,865,000		(104,000		)	30,855,000
Other equity securities	2,490,000		65,000		(4,000		)	2,551,000
	$	181,380,000	$	4,567,000	$	(686,000	)	$	185,261,000
Securities to be held to maturity
U.S. Government-sponsored agencies	$	92,341,000	$	54,000	$	(2,066,000	)	$	90,329,000
Mortgage-backed securities	57,003,000		1,830,000		(116,000		)	58,717,000
State and political subdivisions	126,275,000		4,114,000		(31,000		)	130,358,000
Corporate securities	300,000		—		—			300,000
	$	275,919,000	$	5,998,000	$	(2,213,000	)	$	279,704,000
Restricted equity securities
Federal Home Loan Bank Stock	$	12,875,000	$	—	$	—		$	12,875,000
Federal Reserve Bank Stock	1,037,000		—		—			1,037,000
	$	13,912,000	$	—	$	—		$	13,912,000

The following table summarizes the contractual maturities of investment securities at December 31, 2015:



	Securities available for sale				Securities to be held to maturity
	Amortized Cost		Fair Value (Estimated)		Amortized Cost		Fair Value (Estimated)
Due in 1 year or less	$	527,000	$	530,000	$	1,814,000	$	1,850,000
Due in 1 to 5 years	7,562,000		7,727,000		6,306,000		6,514,000
Due in 5 to 10 years	19,647,000		20,055,000		58,397,000		60,196,000
Due after 10 years	190,194,000		191,304,000		173,506,000		174,563,000
Equity securities	3,381,000		3,423,000		—		—
	$	221,311,000	$	223,039,000	$	240,023,000	$	243,123,000

The following table summarizes the contractual maturities of investment securities at December 31, 2014:



	Securities available for sale				Securities to be held to maturity
	Amortized Cost		Fair Value (Estimated)		Amortized Cost		Fair Value (Estimated)
Due in 1 year or less	$	2,309,000	$	2,329,000	$	1,693,000	$	1,713,000
Due in 1 to 5 years	15,200,000		15,499,000		8,467,000		8,702,000
Due in 5 to 10 years	18,547,000		19,124,000		50,629,000		52,717,000
Due after 10 years	142,834,000		145,758,000		215,130,000		216,572,000
Equity securities	2,490,000		2,551,000		—		—
	$	181,380,000	$	185,261,000	$	275,919,000	$	279,704,000

At December 31, 2015, securities with a fair value of $201,879,000 were pledged to secure borrowings from the Federal Home Loan Bank of Boston, public deposits, repurchase agreements, and for other purposes as required by law. This compares to securities with a fair value of $164,919,000 as of December 31, 2014 pledged for the same purposes.

Gains and losses on the sale of securities available for sale are computed by subtracting the amortized cost at the time of sale from the security's selling price, net of accrued interest to be received.

The following table shows securities gains and losses for 2015, 2014 and 2013:



	2015		2014		2013
Proceeds from sales of securities	$	35,468,000	$	15,557,000	$	10,563,000
Gross realized gains	1,399,000		1,155,000		1,087,000
Gross realized losses	—		—		—
Net gain	$	1,399,000	$	1,155,000	$	1,087,000
Related income taxes	$	490,000	$	404,000	$	380,000

Management reviews securities with unrealized losses for other than temporary impairment. As of December 31, 2015, there were 78 securities with unrealized losses held in the Company's portfolio. These securities were temporarily impaired as a result of changes in interest rates reducing their fair value, of which 15 had been temporarily impaired for 12 months or more. At the present time, there have been no material changes in the credit quality of these securities resulting in other than temporary impairment, and in Management's opinion, no additional write-down for other-than-temporary impairment is warranted.

Information regarding securities temporarily impaired as of December 31, 2015 is summarized below:



	Less than 12 months					12 months or more					Total
	Fair		Unrealized			Fair		Unrealized			Fair		Unrealized
As of December 31, 2015	Value		Losses			Value		Losses			Value		Losses
U.S. Government-sponsored agencies	$	45,311,000	$	(1,469,000	)	$	17,185,000	$	(815,000	)	$	62,496,000	$	(2,284,000	)
Mortgage-backed securities	120,915,000		(1,027,000		)	910,000		(71,000		)	121,825,000		(1,098,000		)
State and political subdivisions	2,528,000		(24,000		)	2,901,000		(63,000		)	5,429,000		(87,000		)
Other equity securities	64,000		(5,000		)	52,000		(1,000		)	116,000		(6,000		)
	$	168,818,000	$	(2,525,000	)	$	21,048,000	$	(950,000	)	$	189,866,000	$	(3,475,000	)

As of December 31, 2014, there were 56 securities with unrealized losses held in the Company's portfolio. These securities were temporarily impaired as a result of changes in interest rates reducing their fair value, of which 36 had been temporarily impaired for 12 months or more. Information regarding securities temporarily impaired as of December 31, 2014 is summarized below:



	Less than 12 months					12 months or more					Total
	Fair		Unrealized			Fair		Unrealized			Fair		Unrealized
As of December 31, 2014	Value		Losses			Value		Losses			Value		Losses
U.S. Government-sponsored agencies	$	—	$	—		$	79,444,000	$	(2,066,000	)	$	79,444,000	$	(2,066,000	)
Mortgage-backed securities	13,878,000		(40,000		)	29,182,000		(654,000		)	43,060,000		(694,000		)
State and political subdivisions	3,352,000		(31,000		)	3,017,000		(104,000		)	6,369,000		(135,000		)
Other equity securities	68,000		(3,000		)	51,000		(1,000		)	119,000		(4,000		)
	$	17,298,000	$	(74,000	)	$	111,694,000	$	(2,825,000	)	$	128,992,000	$	(2,899,000	)

During the third quarter of 2014, the Company transferred securities with a total amortized cost of $89,780,000 and a corresponding fair value of $89,757,000 from available for sale to held to maturity. The net unrealized loss, net of taxes, on these securities at the date of the transfer was $15,000. The net unrealized holding loss at the time of transfer continues to be reported in accumulated other comprehensive income (loss), net of tax and is amortized over the remaining lives of the securities as an adjustment of the yield. The amortization of the net unrealized loss reported in accumulated other comprehensive income (loss) will offset the effect on interest income of the discount for the transferred securities. The remaining unamortized balance of the net unrealized losses for the securities transferred from available for sale to held to maturity was $112,000 at December 31, 2015. These securities were transferred as a part of the Company's overall investment and balance sheet strategies.

The Bank is a member of the Federal Home Loan Bank ("FHLB") of Boston, a cooperatively owned wholesale bank for housing and finance in the six New England States. As a requirement of membership in the FHLB, the Bank must own a minimum required amount of FHLB stock, calculated periodically based primarily on its level of borrowings from the FHLB. The Bank uses the FHLB for much of its wholesale funding needs. As of December 31, 2015 and 2014, the Bank's investment in FHLB stock totaled $13,220,000 and $12,875,000, respectfully. FHLB stock is a restricted equity security and therefore is reported at cost, which equals par value.

The Company periodically evaluates its investment in FHLB stock for impairment based on, among other factors, the capital adequacy of the FHLB and its overall financial condition. No impairment losses have been recorded through December 31, 2015. The Bank will continue to monitor its investment in FHLB stock.