
	Amortized		Unrealized		Unrealized		Fair Value
As of December 31, 2020	Cost		Gains		Losses		(Estimated)
Securities available for sale
U.S. government-sponsored agencies	$	23,045,000	$	—	$	(315,000)	$	22,730,000
Mortgage-backed securities	238,516,000		5,507,000		(617,000)		243,406,000
State and political subdivisions	37,752,000		1,722,000		—		39,474,000
Asset-backed securities	7,723,000		43,000		—		7,766,000

	$	307,036,000	$	7,272,000	$	(932,000)	$	313,376,000
Securities to be held to maturity
U.S. Government-sponsored agencies	$	44,149,000	$	143,000	$	(18,000)	$	44,274,000
Mortgage-backed securities	53,594,000		736,000		(195,000)		54,135,000
State and political subdivisions	245,620,000		10,427,000		(3,000)		256,044,000

Corporate securities	22,250,000		433,000		(2,000)		22,681,000
	$	365,613,000	$	11,739,000	$	(218,000)	$	377,134,000
Restricted equity securities
Federal Home Loan Bank Stock	$	9,508,000	$	—	$	—	$	9,508,000
Federal Reserve Bank Stock	1,037,000		—		—		1,037,000
	$	10,545,000	$	—	$	—	$	10,545,000


	Amortized		Unrealized		Unrealized		Fair Value
As of December 31, 2019	Cost		Gains		Losses		(Estimated)
Securities available for sale
U.S. government-sponsored agencies	$	7,500,000	$	—	$	(102,000)	$	7,398,000
Mortgage-backed securities	323,277,000		4,173,000		(833,000)		326,617,000
State and political subdivisions	25,113,000		1,392,000		—		26,505,000


	$	355,890,000	$	5,565,000	$	(935,000)	$	360,520,000
Securities to be held to maturity
U.S. Government-sponsored agencies	$	32,840,000	$	47,000	$	(26,000)	$	32,861,000
Mortgage-backed securities	14,431,000		450,000		(16,000)		14,865,000
State and political subdivisions	219,585,000		4,936,000		(109,000)		224,412,000
Corporate securities	14,750,000		157,000		—		14,907,000
	$	281,606,000	$	5,590,000	$	(151,000)	$	287,045,000
Restricted equity securities
Federal Home Loan Bank Stock	$	7,945,000	$	—	$	—	$	7,945,000
Federal Reserve Bank Stock	1,037,000		—		—		1,037,000
	$	8,982,000	$	—	$	—	$	8,982,000


	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	$	117,000	$	120,000	$	3,607,000	$	3,641,000
Due in 1 to 5 years	17,718,000		17,915,000		30,867,000		31,792,000
Due in 5 to 10 years	49,697,000		51,001,000		183,679,000		190,153,000
Due after 10 years	239,504,000		244,340,000		147,460,000		151,548,000

	$	307,036,000	$	313,376,000	$	365,613,000	$	377,134,000


	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	$	127,000	$	127,000	$	1,334,000	$	1,338,000
Due in 1 to 5 years	36,534,000		36,778,000		25,860,000		26,323,000
Due in 5 to 10 years	93,134,000		95,014,000		179,133,000		182,834,000
Due after 10 years	226,095,000		228,601,000		75,279,000		76,550,000

	$	355,890,000	$	360,520,000	$	281,606,000	$	287,045,000

At December 31, 2020, securities with a fair value of $297,326,000 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 $214,173,000 as of December 31, 2019 pledged for the same purposes.


	2020		2019		2018
Proceeds from sales of securities	$	112,179,000	$	9,229,000	$	459,000
Gross realized gains	1,689,000		224,000		137,000
Gross realized losses	(534,000)		—		—
Net gain	$	1,155,000	$	224,000	$	137,000
Related income taxes	$	243,000	$	47,000	$	29,000

Sales include 28 municipal securities sold in the second quarter of 2020 that had been designated as Held to Maturity. Proceeds from these sales totaled $8,600,000 against a cumulative book value of $8,313,000 resulting in a net realized gain of $268,000. The economic potential impact of COVID-19 is considered to be an isolated and unusual event that could not be reasonably anticipated as outlined in Accounting Standards Codification ("ASC") Section 320-10-25. Management conducted a review of its municipal bond portfolio in conjunction with risk mitigation efforts related to the onset of the COVID-19 virus; the intent of the review was to identify investment exposures with lower relative credit ratings, locales with perceived above average economic risk, municipal entities with reliance upon sales tax or income tax revenue, or any combination of these factors. Each of the sold positions met one or more of the criteria.

Management reviews securities with unrealized losses for other than temporary impairment. As of December 31, 2020, there were 50 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 10 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.


	Less than 12 months				12 months or more				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
As of December 31, 2020	Value		Losses		Value		Losses		Value		Losses
U.S. Government-sponsored agencies	$	30,212,000	$	(333,000)	$	—	$	—	$	30,212,000	$	(333,000)
Mortgage-backed securities	65,505,000		(724,000)		3,878,000		(88,000)		69,383,000		(812,000)
State and political subdivisions	855,000		(3,000)		—		—		855,000		(3,000)
Corporate securities	2,498,000		(2,000)		—		—		2,498,000		(2,000)

	$	99,070,000	$	(1,062,000)	$	3,878,000	$	(88,000)	$	102,948,000	$	(1,150,000)

As of December 31, 2019, there were 86 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 28 had been temporarily impaired for 12 months or more. Information regarding securities temporarily impaired as of December 31, 2019 is summarized below:


	Less than 12 months				12 months or more				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
As of December 31, 2019	Value		Losses		Value		Losses		Value		Losses
U.S. Government-sponsored agencies	$	12,372,000	$	(128,000)	$	—	$	—	$	12,372,000	$	(128,000)
Mortgage-backed securities	54,244,000		(359,000)		18,696,000		(490,000)		72,940,000		(849,000)
State and political subdivisions	10,532,000		(101,000)		304,000		(8,000)		10,836,000		(109,000)


	$	77,148,000	$	(588,000)	$	19,000,000	$	(498,000)	$	96,148,000	$	(1,086,000)

As disclosed in Note 25, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) No. 2019–04 in April 2019. In December 2019, the Company elected to early adopt the amendments to Topic 815, Derivatives and Hedging, which allowed the Company a one–time reclassification of certain prepayable debt securities from held to maturity to available for sale. In December 2019, prepayable debt securities with a carrying value of $24.9 million and a net unrealized gain of $1.6 million were transferred from held to maturity to available for sale. The reclassified securities consisted of state and political subdivision municipal debt securities. The Company subsequently sold approximately $4.3 million of those securities at a gain of $209,000 recognized in 2019.

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 $133,000, net of taxes, at December 31, 2020. This compares to $182,000, net of taxes, at December 31, 2019. 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, 2020 and 2019, the Bank's investment in FHLB stock totaled $9,508,000 and $7,945,000, respectively. 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, 2020. The Bank will continue to monitor its investment in FHLB stock.