Investment Securities

The amortized cost and fair value of investment securities are shown in the following tables. Management performs a quarterly evaluation of investment securities for any other-than-temporary impairment. For the three and six month periods ended June 30, 2017 and 2016, there were no investment securities deemed to be other-than-temporarily impaired.

Investment securities at June 30, 2017, were as follows:



Securities Available-for-Sale (In thousands)	Amortized Cost		Gross Unrecognized Holding Gains		Gross Unrecognized Holding Losses		Estimated Fair Value
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	270,000	$	—	$	1,314	$	268,686
U.S. Government sponsored entities' asset-backed securities	923,424		6,273		6,104		923,593
Other equity securities	1,109		2,727		—		3,836
Total	$	1,194,533	$	9,000	$	7,418	$	1,196,115



Securities Held-to-Maturity (In thousands)	Amortized Cost		Gross Unrecognized Holding Gains		Gross Unrecognized Holding Losses		Estimated Fair Value
U.S. Government sponsored entities' asset-backed securities	$	61,840	$	1,065	$	24	$	62,881
Obligations of states and political subdivisions	260,168		3,900		$	2,122	261,946
Total	$	322,008	$	4,965	$	2,146	$	324,827

Investment securities with unrecognized losses at June 30, 2017, were as follows:



	Unrecognized loss position for less than 12 months				Unrecognized loss position for 12 months or longer				Total
(In thousands)	Fair value		Unrecognized losses		Fair value		Unrecognized losses		Fair value		Unrecognized losses
Securities Available-for-Sale
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	174,542	$	458	$	94,144	$	856	$	268,686	$	1,314
U.S. Government sponsored entities' asset-backed securities	570,691		5,863		$	24,672	241		$	595,363	6,104
Total	$	745,233	$	6,321	$	118,816	$	1,097	$	864,049	$	7,418
Securities Held-to-Maturity
U.S. Government sponsored entities' asset-backed securities	$	—	$	—	$	7,481	$	24	$	7,481	$	24
Obligations of states and political subdivisions	116,083		$	2,122	—		—		$	116,083	2,122
Total	$	116,083	$	2,122	$	7,481	$	24	$	123,564	$	2,146

Investment securities at December 31, 2016, were as follows:



Securities Available-for-Sale (In thousands)	Amortized Cost		Gross Unrecognized Holding Gains		Gross Unrecognized Holding Losses		Estimated Fair Value
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	270,000	$	—	$	2,467	$	267,533
U.S. Government sponsored entities' asset-backed securities	991,642		5,372		9,842		987,172
Other equity securities	1,119		2,315		—		3,434
Total	$	1,262,761	$	7,687	$	12,309	$	1,258,139



Securities Held-to-Maturity (In thousands)	Amortized Cost		Gross Unrecognized Holding Gains		Gross Unrecognized Holding Losses		Estimated Fair Value
Obligations of states and political subdivision	$	188,622	$	977	$	5,148	$	184,451
U.S. Government sponsored entities' asset-backed securities	71,211		1,097		87		72,221
Total	$	259,833	$	2,074	$	5,235	$	256,672

Investment securities with unrecognized losses at December 31, 2016, were as follows:



	Unrecognized loss position for less than 12 months				Unrecognized loss position for 12 months or longer				Total
(In thousands)	Fair value		Unrecognized losses		Fair value		Unrecognized losses		Fair value		Unrecognized losses
Securities Available-for-Sale
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	247,695	$	2,305	$	19,838	$	162	$	267,533	$	2,467
U.S. Government sponsored entities' asset-backed securities	612,321		9,473		27,325		369		639,646		9,842
Total	$	860,016	$	11,778	$	47,163	$	531	$	907,179	$	12,309
Securities Held-to-Maturity
Obligations of states and political subdivision	$	134,909	$	5,148	$	—	$	—	$	134,909	$	5,148
U.S. Government sponsored entities' asset-backed securities	—		—		7,564		87		7,564		87
Total	$	134,909	$	5,148	$	7,564	$	87	$	142,473	$	5,235

Management does not believe any of the unrecognized losses at June 30, 2017 or December 31, 2016 represented other-than-temporary impairment. Should the impairment of any of these securities become other-than-temporary, the cost basis of the investment will be reduced and the resulting loss recognized within net income in the period the other-than-temporary impairment is identified.

Park’s U.S. Government sponsored entities' asset-backed securities consist of 15-year residential mortgage-backed securities and collateralized mortgage obligations.

The amortized cost and estimated fair value of investments in debt securities at June 30, 2017, are shown in the following table by contractual maturity, except for asset-backed securities, which are shown as a single total, due to the unpredictability of the timing of principal repayments.



Securities Available-for-Sale (In thousands)	Amortized cost		Fair value		Tax equivalent yield
Obligations of U.S. Treasury and other U.S. Government sponsored entities' obligations:
Due less than one year	$	75,000	$	74,900	1.02	%
Due one through five years	195,000		193,786		1.25	%
Total	$	270,000	$	268,686	1.18	%


U.S. Government sponsored entities' asset-backed securities	$	923,424	$	923,593	2.09	%



Securities Held-to-Maturity (In thousands)	Amortized cost		Fair value		Tax equivalent yield⁽¹⁾
Obligations of state and political subdivisions:
Due over ten years	$	260,168	$	261,946	4.49	%
Total ⁽¹⁾	$	260,168	$	261,946	4.49	%

U.S. Government sponsored entities' asset-backed securities	$	61,840	$	62,881	3.23	%

(1) The tax equivalent yield for obligations of state and political subdivisions includes the effects of a taxable equivalent adjustment using a 35% rate. The aggregate taxable equivalent adjustment was $1.7 million for the six months ended June 30, 2017.

All of Park’s securities shown in the table above as obligations of U.S. Treasury and other U.S. Government sponsored entities' notes are callable notes. These callable notes have final maturities of 0.4 years to 3 years. Of the $268.7 million reported at June 30, 2017, none were expected to be called. The remaining average life of the entire investment portfolio is estimated to be 4.4 years.

There were no sales of investment securities during the three-month or six-month periods ended June 30, 2017 or 2016.

Investment securities having an amortized cost of $944 million and $937 million at June 30, 2017 and December 31, 2016, respectively, were pledged to collateralize government and trust department deposits in accordance with federal and state requirements, to secure repurchase agreements sold and as collateral for FHLB advance borrowings.