Investments

Investments at December 31, 2017 and 2016 consisted of mutual funds, United States corporate debt securities and an equity investment in the Company's affiliated entity PLS. The Company classifies all investments as available-for-sale, as the sale of such investments may be required prior to maturity to implement management strategies. Available-for-sale securities are recorded at fair value, based on current market valuations. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a separate component of other comprehensive loss until realized. Realized gains and losses are included in non-operating other income (expense) on the consolidated statement of operations and are derived using the specific identification method for determining the cost of the securities sold. During the years ended December 31, 2017 and 2016, net realized loss on investments of $215,000 and $139,000 was recorded, respectively. The Company assessed each of its investments on an individual basis to determine if any decline in fair value was other-than-temporary. There were no impairments considered to be other-than-temporary during the years ended December 31, 2017 and 2016. Interest and dividends on investments classified as available-for-sale are included in interest and other income, net, in the consolidated statements of operations. As of December 31, 2017, the Company had 42 available-for-sale securities in a gross unrealized loss position, of which 16 with an aggregate total unrealized loss of $108,000 were in such position for longer than 12 months.

The following is a summary of available-for-sale securities as of December 31, 2017 and 2016:



		As of December 31, 2017
	Contractual Maturity (in years)	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value
Mutual funds	---	$	68,776,165	$	42,097	$	(252,373	)	$	68,565,889
US corporate debt securities	Less than 2	35,210,121		3,032		(140,198		)	35,072,955
Investment in affiliated entity (PLS)	---	—		2,325,079		—			2,325,079
Total investments		$	103,986,286	$	2,370,208	$	(392,571	)	$	105,963,923



		As of December 31, 2016
	Contractual Maturity (in years)	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value
Mutual funds	---	$	60,883,065	$	94,374	$	(387,693	)	$	60,589,746
US corporate debt securities	Less than 2	25,098,122		6,853		(65,309		)	25,039,666
Investment in affiliated entity (PLS)	---	—		3,777,510		—			3,777,510
Total investments		$	85,981,187	$	3,878,737	$	(453,002	)	$	89,406,922