5. Investments

The amortized cost and estimated fair value of investments in debt and equity securities by category is as follows (in thousands):


			Gross		Gross
			Unrealized		Unrealized
	Amortized Cost		Gains		Losses		Fair Value
As of March 31, 2020
U.S. Treasury securities and obligations of U.S. Government	$	154,303	$	1,011	$	(27)	$	155,287
Corporate bonds		302,433		1,357		(4,949)		298,841
Collateralized corporate bank loans		62,993		-		(5,829)		57,164
Municipal bonds		69,876		719		(67)		70,528
Mortgage-backed		7,565		87		(89)		7,563
Total debt securities		597,170		3,174		(10,961)		589,383
Total equity securities		19,783		1,789		(7,433)		14,139
Total other investments		3,763		—		(3,595)		168
Total investments	$	620,716	$	4,963	$	(21,989)	$	603,690

As of December 31, 2019
U.S. Treasury securities and obligations of U.S. Government	$	66,441	$	162	$	(3)	$	66,600
Corporate bonds		297,601		3,387		(163)		300,825
Collateralized corporate bank loans		115,669		556		(468)		115,757
Municipal bonds		81,787		1,531		(48)		83,270
Mortgage-backed		8,000		46		(219)		7,827
Total debt securities		569,498		5,682		(901)		574,279
Total equity securities		71,895		35,028		(7,708)		99,215
Total other investments		3,763		—		(1,594)		2,169
Total investments	$	645,156	$	40,710	$	(10,203)	$	675,663

Major categories of net investment (losses) gains on investments are summarized as follows (in thousands):


	Three Months Ended March 31,
	2020		2019
U.S. Treasury securities and obligations of U.S. Government	$	—	$	—
Corporate bonds		55		23
Collateralized corporate bank loans		(148)		17
Municipal bonds		1,420		4,101
Mortgage-backed		—		—
Equity securities		4,309		—
Gain on investments		5,636		4,141
Unrealized (losses) gains on other investments		(2,001)		36
Unrealized (losses) gains on equity investments		(32,965)		7,760
Investment (losses) gains, net	$	(29,330)	$	11,937

We realized gross gains on investments of $20.4 million and $4.2 million during the three months ended March 31, 2020 and 2019, respectively. We realized gross losses on investments of $14.8 million and $0.1 million for the three months ended March 31, 2020 and 2019, respectively. We had proceeds from the sale of investment securities of $100.8 million during the three months ended March 31, 2020. We had no proceeds from the sale of investment securities during the three months ended March 31, 2019. Realized investment gains and losses are recognized in operations on the first in-first out method.

The following schedules summarize the gross unrealized losses showing the length of time that investments have been continuously in an unrealized loss position as of March 31, 2020 and December 31, 2019 (in thousands):


	As of March 31, 2020
	12 months or less				Longer than 12 months				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
U.S. Treasury securities and obligations of U.S. Government	$	110,938	$	(27)	$	—	$	—	$	110,938	$	(27)
Corporate bonds		174,415		(4,927)		1,331		(22)		175,746		(4,949)
Collateralized corporate bank loans		51,030		(4,664)		6,133		(1,165)		57,163		(5,829)
Municipal bonds		6,178		(44)		1,721		(23)		7,899		(67)
Mortgage-backed		2,457		(83)		14		(6)		2,471		(89)
Total debt securities		345,018		(9,745)		9,199		(1,216)		354,217		(10,961)
Total equity securities		10,924		(4,208)		1,160		(3,225)		12,084		(7,433)
Total other investments		—		—		168		(3,595)		168		(3,595)
Total investments	$	355,942	$	(13,953)	$	10,527	$	(8,036)	$	366,469	$	(21,989)


	As of December 31, 2019
	12 months or less				Longer than 12 months				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
U.S. Treasury securities and obligations of U.S. Government	$	—	$	—	$	5,513	$	(3)	$	5,513	$	(3)
Corporate bonds		27,268		(144)		1,150		(19)		28,418		(163)
Collateralized corporate bank loans		9,000		(41)		10,228		(427)		19,228		(468)
Municipal bonds		4,808		(29)		1,618		(19)		6,426		(48)
Mortgage-backed		1,712		(101)		562		(118)		2,274		(219)
Total debt securities		42,788		(315)		19,071		(586)		61,859		(901)
Total equity securities		10,905		(2,363)		6,093		(5,345)		16,998		(7,708)
Total other investments		—		—		2,169		(1,594)		2,169		(1,594)
Total investments	$	53,693	$	(2,678)	$	27,333	$	(7,525)	$	81,026	$	(10,203)

We had a total of 167 debt securities with an unrealized loss, of which 150 were in an unrealized loss position for less than one year and 17 were in an unrealized loss position for a period of one year or greater, as of March 31, 2020. We held a total of 61 debt securities with an unrealized loss, of which 41 were in an unrealized loss position for less than one year and 20 were in an unrealized loss position for a period of one year or greater, as of December 31, 2019. We consider these losses as a temporary decline in value as they are predominately on securities that we do not intend to sell and do not believe we will be required to sell prior to recovery of our amortized cost basis. The gross unrealized losses on the debt security positions at March 31, 2020 were due predominately to market and interest rate fluctuations and we see no other indications that the decline in values of these securities is other-than-temporary.

Based on evidence gathered through our normal credit evaluation process, we presently expect that all debt securities held in our investment portfolio will be paid in accordance with their contractual terms. Nonetheless, it is at least reasonably possible that the performance of certain issuers of these debt securities will be worse than currently expected resulting in future write-downs within our portfolio of debt securities.

Also, as a result of the challenging market conditions, we expect the volatility in the valuation of our equity securities to continue in the foreseeable future. This volatility may lead to changes regarding retention strategies for certain equity securities.

We complete a detailed analysis each quarter to assess whether any decline in the fair value of any debt security below cost is deemed other-than-temporary. All debt securities with an unrealized loss are reviewed. We recognize an impairment loss when a debt security’s value declines below cost, adjusted for accretion, amortization and previous other-than-temporary impairments and it is determined that the decline is other-than-temporary. We did not recognize an impairment loss during the three months ended March 31, 2020 or 2019.

Debt Investments: We assess whether we intend to sell, or it is more likely than not that we will be required to sell, a fixed maturity investment before recovery of its amortized cost basis less any current period credit losses. For fixed maturity investments that are considered other-than-temporarily impaired and that we do not intend to sell and will not be required to sell, we separate the amount of the impairment into the amount that is credit related (credit loss component) and the amount due to all other factors. The credit loss component is recognized in earnings and is the difference between the investment’s amortized cost basis and the present value of its expected future cash flows. The remaining difference between the investment’s fair value and the present value of future expected cash flows is recognized in other comprehensive income. During the three months ended March 31, 2020 we did not dispose of previously impaired securities. During the three months ended March 31, 2019 we disposed of six previously impaired securities and recognized a realized gain of $4.1 million.

Equity Investments: On January 1, 2018, we adopted ASU 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities (Topic 825).” ASU 2016-01 requires equity investments that are not consolidated or accounted for under the equity method of accounting to be measured at fair value with changes in fair value recognized in net income each reporting period. As a result of this standard, equity securities with readily determinable fair values are not required to be evaluated for other-than-temporary-impairment.

Details regarding the carrying value of the other investments portfolio as of March 31, 2020 and December 31, 2019 are as follows (in thousands):


	2020		2019
Investment Type
Equity warrant	$	168	$	2,169
Total other investments	$	168	$	2,169

We acquired this warrant in an active market. The warrant entitles us to buy the underlying common stock of a publicly traded company at a fixed price until the expiration date of January 19, 2021.

The amortized cost and estimated fair value of debt securities at March 31, 2020 by contractual maturity are as follows. Expected maturities may differ from contractual maturities because certain borrowers may have the right to call or prepay obligations with or without penalties.


	Amortized Cost		Fair Value
	(in thousands)
Due in one year or less	$	212,895	$	213,273
Due after one year through five years		319,397		314,222
Due after five years through ten years		38,117		35,813
Due after ten years		19,196		18,512
Mortgage-backed		7,565		7,563
	$	597,170	$	589,383