4. 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 September 30, 2019
U.S. Treasury securities and obligations of U.S. Government	$	48,246	$	121	$	(22)	$	48,345
Corporate bonds		281,228		3,068		(174)		284,122
Collateralized corporate bank loans		121,741		363		(787)		121,317
Municipal bonds		104,540		1,826		(55)		106,311
Mortgage-backed		8,847		38		(149)		8,736
Total debt securities		564,602		5,416		(1,187)		568,831
Total equity securities		68,737		30,124		(6,762)		92,099
Total other investments		3,763		—		(754)		3,009
Total investments	$	637,102	$	35,540	$	(8,703)	$	663,939

As of December 31, 2018
U.S. Treasury securities and obligations of U.S. Government	$	48,609	$	5	$	(508)	$	48,106
Corporate bonds		243,314		440		(1,602)		242,152
Collateralized corporate bank loans		131,779		19		(5,270)		126,528
Municipal bonds		112,574		3,791		(838)		115,527
Mortgage-backed		13,992		11		(446)		13,557
Total debt securities		550,268		4,266		(8,664)		545,870
Total equity securities		68,709		20,693		(8,506)		80,896
Total other investments		3,763		—		(2,615)		1,148
Total investments	$	622,740	$	24,959	$	(19,785)	$	627,914

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


	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
U.S. Treasury securities and obligations of U.S. Government	$	—	$	—	$	—	$	—
Corporate bonds		154		(44)		171		(66)
Collateralized corporate bank loans		(103)		23		(65)		70
Municipal bonds		124		(145)		4,271		(164)
Mortgage-backed		—		—		(1)		1
Equity securities		—		—		—		359
Gain (loss) on investments		175		(166)		4,376		200
Unrealized (losses) gains on equity securities		(1,941)		7,121		11,175		3,217
Unrealized (losses) gains on other investments		424		25		1,861		(739)
Investment (losses) gains, net	$	(1,342)	$	6,980	$	17,412	$	2,678

We realized gross gains on investments of $0.5 million and $0.3 million during the three months ended September 30, 2019 and 2018, respectively and $4.9 million and $0.9 million for the nine months ended September 30, 2019 and 2018, respectively. We realized gross losses on investments of $0.3 million and $0.5 million for the three months ended September 30, 2019 and 2018, respectively, and $0.5 million and $0.7 million for the nine months ended September 30, 2019 and 2018, respectively. We recorded proceeds from the sale of investment securities of $6.0 million and $0.4 million during the three months ended September 30, 2019 and 2018, respectively, and $13.0 million and $14.6 million for the nine months ended September 30, 2019 or 2018, respectively. 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 September 30, 2019 and December 31, 2018 (in thousands):


	As of September 30, 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	$	—	$	—	$	23,142	$	(22)	$	23,142	$	(22)
Corporate bonds		29,172		(142)		13,305		(32)		42,477		(174)
Collateralized corporate bank loans		33,961		(636)		4,782		(151)		38,743		(787)
Municipal bonds		6,537		(48)		1,036		(7)		7,573		(55)
Mortgage-backed		1,384		(65)		599		(84)		1,983		(149)
Total debt securities		71,054		(891)		42,864		(296)		113,918		(1,187)
Total equity securities		9,538		(4,275)		2,391		(2,487)		11,929		(6,762)
Total other investments		—		—		3,009		(754)		3,009		(754)
Total investments	$	80,592	$	(5,166)	$	48,264	$	(3,537)	$	128,856	$	(8,703)


	As of December 31, 2018
	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	$	18,902	$	(181)	$	28,201	$	(327)	$	47,103	$	(508)
Corporate bonds		117,450		(907)		100,060		(695)		217,510		(1,602)
Collateralized corporate bank loans		120,410		(4,938)		4,931		(332)		125,341		(5,270)
Municipal bonds		14,281		(96)		25,891		(742)		40,172		(838)
Mortgage-backed		6,592		(60)		5,986		(386)		12,578		(446)
Total debt securities		277,635		(6,182)		165,069		(2,482)		442,704		(8,664)
Total equity securities		30,981		(3,699)		4,475		(4,807)		35,456		(8,506)
Total other investments		1,148		(2,615)		—		—		1,148		(2,615)
Total investments	$	309,764	$	(12,496)	$	169,544	$	(7,289)	$	479,308	$	(19,785)

We had a total of 81 debt securities with an unrealized loss, of which 58 were in an unrealized loss position for less than one year and 23 were in an unrealized loss position for a period of one year or greater, as of September 30, 2019. We had a total of 328 debt securities with an unrealized loss, of which 221 were in an unrealized loss position for less than one year and 107 were in an unrealized loss position for a period of one year or greater, as of December 31, 2018. 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. We see no other indications that the decline in values of these securities is other-than-temporary.

We complete a detailed analysis each quarter to assess whether any decline in the fair value of any fixed maturity investment below cost is deemed other-than-temporary. All fixed maturity investments with an unrealized loss are reviewed. We recognize an impairment loss when an investment’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 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.

Details regarding the carrying value of the other investments portfolio as of September 30, 2019 and December 31, 2018 are as follows (in thousands):


	September 30,		December 31,
	2019		2018
Investment Type
Equity warrant	$	3,009	$	1,148
Total other investments	$	3,009	$	1,148

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 September 30, 2019 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	$	121,593	$	121,977
Due after one year through five years		309,542		312,076
Due after five years through ten years		94,338		94,489
Due after ten years		30,282		31,553
Mortgage-backed		8,847		8,736
	$	564,602	$	568,831