Investment Securities

The carrying values and approximate fair values of investment securities at the periods indicated are presented below:



(In Thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
December 31, 2017
Securities available for sale
U.S. Treasury and government sponsored entities		$250,794		$3		$1,336		$249,461
Municipal securities	14,395		72		46		14,421
Corporate bonds	36,654		478		—		37,132
Collateralized loan obligations	6,000		5		—		6,005
Preferred stock	5,422		338		29		5,731
Total securities available for sale		$313,265		$896		$1,411		$312,750
December 31, 2016
Securities available for sale
U.S. Treasury and government sponsored entities		$264,267		$150		$1,056		$263,361
Municipal securities	18,184		26		53		18,157
U.S. Agency mortgage-backed securities	2		—		—		2
Corporate bonds	44,437		295		—		44,732
Preferred stock	4,922		49		4		4,967
Total securities available for sale		$331,812		$520		$1,113		$331,219
Securities held to maturity
Municipal securities		$899		$23		$—		$922
Total securities held to maturity		$899		$23		$—		$922

Gross unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2017 and 2016, were as follows:



	Less Than 12 Months				More Than 12 Months				Total
(In Thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
2017:
Securities Available for Sale
U.S. Treasury and government sponsored entities		$116,331		$496		$122,605		$840		$238,936		$1,336
Municipal securities	3,994		17		2,298		29		6,292		46
Preferred stock	1,013		29		—		—		1,013		29
Total		$121,338		$542		$124,903		$869		$246,241		$1,411
2016:
Securities Available for Sale
U.S. Treasury and government sponsored entities		$180,638		$1,051		$489		$5		$181,127		$1,056
Municipal securities	11,533		33		1,786		20		13,319		53
Preferred stock	—		—		1,038		4		1,038		4
Total		$192,171		$1,084		$3,313		$29		$195,484		$1,113

The unrealized losses on investments in government sponsored entities, corporate bonds, municipal securities, and preferred stock in both periods were caused by changes in interest rates. At December 31, 2017 and 2016, there were 24 and 34 available for sale securities in an unrealized loss position, respectively, that have been in a loss position for less than twelve months. There were 17 and 4 securities with unrealized losses at December 31, 2017 and 2016, respectively, that have been at a loss position for more than twelve months. The contractual terms of these investments do not permit the issuer to settle the securities at a price less than the amortized cost of the investment. Because it is more likely than not that the Company will hold these investments until a market price recovery or maturity, these investments are not considered other-than-temporarily impaired.

At December 31, 2017 and 2016, $51.6 million and $50.9 million in securities were pledged for deposits and borrowings, respectively.

The amortized cost and fair values of debt securities at December 31, 2017, are distributed by contractual maturity as shown below. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Although preferred stock has no stated maturity, it is aggregated in the calculation of weighted average yields presented below in the category of investments that mature in ten years or more.



(In Thousands)	Amortized Cost		Fair Value		Weighted Average Yield
U.S. Treasury and government sponsored entities
Within 1 year		$113,087		$112,755	1.08	%
1-5 years		$137,707		$136,706	1.63	%
Total		$250,794		$249,461	1.38	%
Corporate bonds
Within 1 year		$4,500		$4,504	2.10	%
1-5 years	21,704		21,952		2.14	%
5-10 years	10,450		10,676		2.58	%
Total		$36,654		$37,132	2.26	%
Collateralized loan obligations
5-10 years		$3,000		$3,000	3.03	%
Over 10 years	3,000		3,005		3.09	%
Total		$6,000		$6,005	3.06	%
Preferred stock
Over 10 years		$5,422		$5,731	6.37	%
Total		$5,422		$5,731	6.37	%
Municipal securities
Within 1 year		$3,730		$3,728	1.64	%
1-5 years	10,665		10,693		2.66	%
Total		$14,395		$14,421	2.40	%

The proceeds and resulting gains and losses, computed using specific identification, from sales of investment securities for the years ending December 31, 2017, 2016, and 2015, respectively, are as follows:



(In Thousands)	Proceeds		Gross Gains		Gross Losses
2017
Available for sale securities		$25,006		$14		$3
2016
Available for sale securities		$5,785		$12		$23
2015
Available for sale securities		$20,522		$271		$—

A summary of interest income for the years ending December 31, 2017, 2016, and 2015 on available for sale investment securities is as follows:



(In Thousands)	2017		2016		2015
U.S. Treasury and government sponsored entities		$2,983		$2,661		$2,378
U.S. Agency mortgage-backed securities	—		4		25
Other	1,225		948		670
Total taxable interest income		$4,208		$3,613		$3,073
Municipal securities		$367		$282		$320
Total tax-exempt interest income		$367		$282		$320
Total		$4,575		$3,895		$3,393