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. During 2019, 2018 and 2017, there were no investment securities deemed to be other-than-temporarily impaired.


(In thousands)	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
2019:
Debt Securities Available-for-Sale
Obligations of states and political subdivisions	$	302,928	$	17,563	$	—	$	320,491
U.S. Government sponsored entities’ asset-backed securities	884,571		10,862		6,223		889,210
Total	$	1,187,499	$	28,425	$	6,223	$	1,209,701


(In thousands)	Amortized Cost		Gross Unrealized/Unrecognized Holding Gains		Gross Unrealized/Unrecognized Holding Losses		Fair Value
2018:
Debt Securities Available-for-Sale
U.S. Government sponsored entities’ asset-backed securities	$	1,028,883	$	453	$	25,915	$	1,003,421
Total	$	1,028,883	$	453	$	25,915	$	1,003,421
2018:
Debt Securities Held-to-Maturity
Obligations of states and political subdivisions	$	305,278	$	3,202	$	2,672	$	305,808
U.S. Government sponsored entities’ asset-backed securities	46,530		87		1,003		45,614
Total	$	351,808	$	3,289	$	3,675	$	351,422

Park’s U.S. Government sponsored entities' asset-backed securities consisted primarily of 15-year residential mortgage-backed securities and collateralized mortgage obligations ("CMOs"). At December 31, 2019, the amortized cost of Park’s AFS mortgage-backed securities was $581.0 million within Park's investment portfolio. At December 31, 2019, the amortized cost of Park's AFS CMOs was $303.6 million.

On September 1, 2019, Park adopted the portion of ASU 2019-04 which allowed for a one-time reclassification of securities from HTM to AFS. On that date, Park transferred HTM securities with a fair value of $373.9 million to the AFS classification. The transfer occurred at fair value and had a related unrealized gain, net of taxes, of $19.1 million recorded in other comprehensive income.

The following table provides detail on investment securities with unrealized/unrecognized losses aggregated by investment category and length of time the individual securities had been in a continuous loss position at December 31, 2019 and December 31, 2018:


	Less than 12 Months						12 Months or Longer				Total
(In thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
2019:
Debt Securities Available-for-Sale
U.S. Government sponsored entities' asset-backed securities	$	237,613	$	1,106	$	171,805	$	5,117	$	409,418	$	6,223
Total	$	237,613	$	1,106	$	171,805	$	5,117	$	409,418	$	6,223


	Less than 12 Months						12 Months or Longer				Total
(In thousands)	Fair Value		Unrealized/Unrecognized Losses		Fair Value		Unrealized/Unrecognized Losses		Fair Value		Unrealized/Unrecognized Losses
2018:
Debt Securities Available-for-Sale
U.S. Government sponsored entities' asset-backed securities	$	506,280	$	5,998	$	449,569	$	19,917	$	955,849	$	25,915
Total	$	506,280	$	5,998	$	449,569	$	19,917	$	955,849	$	25,915
2018:
Debt Securities Held-to-Maturity
Obligations of states and political subdivisions	$	91,960	$	1,095	$	70,723	$	1,577	$	162,683	$	2,672
U.S. Government sponsored entities' asset-backed securities	32,656		838		6,931		165		39,587		1,003
Total	$	124,616	$	1,933	$	77,654	$	1,742	$	202,270	$	3,675

Management does not believe any individual unrealized/unrecognized loss as of December 31, 2019 or 2018 represented an other-than-temporary impairment. The unrealized/unrecognized losses on agency issued and non-agency issued debt securities are primarily the result of interest rate changes. These conditions will not prohibit Park from receiving its contractual principal and interest payments on these debt securities. The fair value of these debt securities is expected to recover as payments are received on these securities and they approach maturity. 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 attributable to credit will be recognized in net income in the period the other-than-temporary impairment is identified.

The amortized cost and estimated fair value of investments in debt securities at December 31, 2019, 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 in principal repayments.


(In thousands)	Amortized Cost		Fair Value		Tax Equivalent Yield ⁽¹⁾
Debt Securities Available-for-Sale
Obligations of states and political subdivisions
Due five through ten years	$	3,984	$	4,135	3.04	%
Due greater than ten years	298,944		316,356		3.69	%
Total	$	302,928	$	320,491	3.68	%

U.S. Government sponsored entities’ asset-backed securities	$	884,571	$	889,210	2.37	%

(1) The tax equivalent yield for obligations of states and political subdivisions includes the effects of a taxable equivalent adjustment using a 21% federal corporate income tax rate.

At December 31, 2019, investment securities with an amortized cost of $370 million were pledged for government and trust department deposits, $197 million were pledged to secure repurchase agreements and $18 million were pledged as collateral for FHLB advance borrowings. At December 31, 2018, investment securities with an amortized cost of $332 million were pledged for government and trust department deposits, $280 million were pledged to secure repurchase agreements and $22 million were pledged as collateral for FHLB advance borrowings.

At December 31, 2019, there were no holdings of securities of any one issuer, other than the U.S. Government and its agencies, in an amount greater than 10% of shareholders’ equity.

During 2019, Park sold certain AFS debt securities with a book value of $62.4 million at a gross loss of $692,000, and sold certain AFS debt securities with a book value of $29.1 million at a gross gain of $271,000. During 2018, Park sold certain AFS debt securities with a book value of $245.0 million at a gross loss of $2.6 million, sold certain AFS debt securities with a book value of $2.0 million at a gross gain of $60,000, and sold certain HTM debt securities with a book value of $7.4 million at a

gross gain of $0.3 million. These HTM debt securities had been paid down by 96.3% of the principal outstanding at acquisition. During 2017, Park sold certain equity securities with a book value of $444,000 at a gain of $1.8 million.

Other investment securities (as shown on the Consolidated Balance Sheets) consist of stock investments in the FHLB, the FRB, and equity securities. The FHLB and FRB restricted stock investments are carried at their redemption value. Equity securities with a readily determinable fair value are carried at fair value. Equity securities without a readily determinable fair value are recorded at cost, minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions ("modified cost"). Park's portfolio of equity investments in limited partnerships which provide mezzanine funding ("Partnership Investments") are valued using the net asset value practical expedient in accordance with ASC 820.


(In thousands)	December 31, 2019		December 31, 2018
FHLB stock	$	30,060	$	43,388
FRB stock	14,653		8,225
Equity investments carried at fair value	1,993		1,649
Equity investments carried at modified cost ⁽¹⁾	2,689		2,589
Equity investments carried at net asset value	20,411		17,065
Total other investment securities	$	69,806	$	72,916

During the year ended December 31, 2019, the FHLB repurchased 123,472 shares of FHLB stock with a book value of $13.3 million, and Park purchased 128,553 shares of FRB stock with a book value of $6.4 million. During the year ended December 31, 2018, the FHLB repurchased 66,980 shares of FHLB stock with a book value of $6.7 million. No shares of FRB stock were purchased or sold in 2018.

For the years ended December 31, 2019 and 2018, $345,000 and $(287,000), respectively, of unrealized gains (losses) on equity investments carried at fair value were recorded within "Gain on equity securities, net" on the Consolidated Statements of Income. An additional $3.5 million gain recorded within "Gain on equity securities, net" on the Consolidated Statements of Income for the year ended December 31, 2018 relates to Park's 8.55% investment in NewDominion which was held at December 31, 2017. See Note 4 - Business Combinations.

For the years ended December 31, 2019 and 2018, $4.8 million and $1.4 million, respectively, of gains on equity investments carried at NAV were recorded within "Gain on equity securities, net" on the Consolidated Statements of Income.