The following table summarizes the amortized cost and fair value of debt securities at December 31, 2021 and December 31, 2020 and the corresponding amounts of gross unrealized gains and losses recognized in accumulated other comprehensive income (loss). There was no related allowance for credit losses at December 31, 2021.


(In thousands)	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
2021:
Debt Securities Available-for-Sale
Obligations of states and political subdivisions	$	366,933	$	22,682	$	24	$	389,591
U.S. Government sponsored entities’ asset-backed securities	849,114		13,437		8,088		854,463
Collateralized loan obligations	500,066		3		1,395		498,674
Corporate debt securities	11,250		169		7		11,412
Total	$	1,727,363	$	36,291	$	9,514	$	1,754,140


(In thousands)	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
2020:
Debt Securities Available-for-Sale
Obligations of states and political subdivisions	$	279,245	$	25,973	$	—	$	305,218
U.S. Government sponsored entities’ asset-backed securities	726,589		26,248		728		752,109
Corporate debt securities	2,000		14		—		2,014
Total	$	1,007,834	$	52,235	$	728	$	1,059,341

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. All debt securities were classified as AFS at December 31, 2021 and December 31, 2020.

The following table provides detail on investment securities in an unrealized loss position for which an allowance for credit losses has not been recorded at December 31, 2021, aggregated by major security type and length of time in a continuous unrealized loss position:


	Less than 12 Months				12 Months or Longer				Total
(In thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
2021:
Debt Securities Available-for-Sale
Obligations of states and political subdivisions	$	1,834	$	24	$	—	$	—	$	1,834	$	24
U.S. Government sponsored entities’ asset-backed securities	333,653		4,996		73,431		3,092		407,084		8,088
Collateralized loan obligations	429,671		1,395		—		—		429,671		1,395
Corporate debt securities	2,243		7		—		—		2,243		7
Total	$	767,401	$	6,422	$	73,431	$	3,092	$	840,832	$	9,514


	Less than 12 Months				12 Months or Longer				Total
(In thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
2020:
Debt Securities Available-for-Sale
U.S. Government sponsored entities' asset-backed securities	$	86,393	$	695	$	4,727	$	33	$	91,120	$	728
Total	$	86,393	$	695	$	4,727	$	33	$	91,120	$	728

At December 31, 2021, Park’s debt security portfolio consisted of $1.8 billion of securities, $840.8 million of which were in an unrealized loss position with unrealized losses of $9.5 million. Of the $840.8 million of securities in an unrealized loss position, $73.4 million were in an unrealized loss position for 12 months or longer. The majority of the unrealized losses were related to Park’s U.S. Government sponsored entities' asset-backed securities portfolio. Unrealized losses have not been recognized into earnings as they represent negative adjustments to fair value relative to the rate of interest paid on the securities and not losses related to the creditworthiness of the respective issuers. Management does not intend to sell, and it is not more likely than not that management would be required to sell, the securities prior to their anticipated recovery. Management believes the value will recover as the securities approach maturity or market rates change.

There was no allowance for credit losses recorded for debt securities AFS at December 31, 2021. Additionally, for the years ended December 31, 2021, 2020, and 2019, there were no credit-related investment impairment losses recognized.

The amortized cost and estimated fair value of investments in debt securities at December 31, 2021, are shown in the following table by contractual maturity, except for asset-backed securities and collateralized loan obligations, which are shown as a single total, due to the unpredictability of the timing in principal repayments. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties.


(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	$	197,895	$	213,154	3.75	%
Due greater than ten years	169,038		176,437		2.91	%
Total	$	366,933	$	389,591	3.36	%

U.S. Government sponsored entities’ asset-backed securities	$	849,114	$	854,463	1.73	%

Collateralized loan obligations	$	500,066	$	498,674	1.61	%

Corporate debt securities
Due five through ten years	$	11,250	$	11,412	3.93	%

At December 31, 2021, investment securities with an amortized cost of $396.3 million were pledged for government and trust department deposits, $327.9 million were pledged to secure repurchase agreements and $9.5 million were pledged as collateral for FHLB advance borrowings. At December 31, 2020, investment securities with an amortized cost of $328.6 million were pledged for government and trust department deposits, $348.6 million were pledged to secure repurchase agreements and $13.9 million were pledged as collateral for FHLB advance borrowings.

There were no sales of AFS debt securities during 2021. During 2020, Park sold certain AFS debt securities with a book value of $112.5 million at a gross loss of $64,000, and sold certain AFS debt securities with a book value of $196.4 million at a gross gain of $3.4 million. During 2019, Park sold certain AFS debt securities with a book value of $62.4 million at a gross loss of $0.7 million and sold certain AFS debt securities with a book value of $29.1 million at a gross gain of $271,000.

Other investment securities (as shown on the Consolidated Balance Sheets) consist of restricted stock investments in the FHLB and 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, 2021		December 31, 2020
FHLB stock	$	13,413	$	22,090
FRB stock	14,653		14,653
Equity investments carried at fair value	2,129		2,511
Equity investments carried at modified cost (1)	4,689		4,689
Equity investments carried at net asset value	26,384		21,522
Total other investment securities	$	61,268	$	65,465

During the year ended December 31, 2021, the FHLB repurchased 86,770 shares of FHLB stock with a book value of $8.7 million. No shares of FRB stock were purchased or sold in 2021. During the year ended December 31, 2020, the FHLB repurchased 79,697 shares of FHLB stock with a book value of $8.0 million. No shares of FRB stock were purchased or sold in 2020. During the year ended December 31, 2019, the FHLB repurchased 133,281 shares of FHLB stock with a book value of $13.3 million. Park purchased 128,553 shares of FRB stock with a book value of $6.4 million in 2019.

For the years ended December 31, 2021, 2020 and 2019, $552,000, $(239,000) and $345,000, respectively, of gains (losses) on equity investments carried at fair value were recorded within "Gain on equity securities, net" on the Consolidated Statements of Income.

For the years ended December 31, 2021, 2020 and 2019, $4.5 million, $2.4 million and $4.8 million, respectively, of gains on equity investments carried at NAV were recorded within "Gain on equity securities, net" on the Consolidated Statements of Income.