3.	Investments.

Available-for-sale investments by security type were as follows:


	Amortized cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
At December 31, 2018:
U.S. Treasuries – ST	$	10,382,699	$	—	$	(1,835	)	$	10,380,864
U.S. Treasuries – LT		5,026,656		—		(18,413	)		5,008,243

Total	$	15,409,355	$	—	$	(20,248	)	$	15,389,107

At December 31, 2017, the Company did not have any available-for-sale securities.

In accordance with FASB ASC Topic 320, “Investments – Debt and Equity Securities”, or ASC 320, the Company has classified its U.S. Treasuries as available-for-sale securities with secondary or resale markets, and, as such, they are reported at fair value with unrealized gains and losses included in comprehensive loss in stockholders’ equity and realized gain and losses, included in other income, net. There were no realized gains or losses from sales of available-for-sale securities for the years ended December 31, 2018 or 2017.

Certain U.S. Treasuries at December 31, 2018 had fair values less than their amortized costs and, therefore, contained unrealized losses. Given that the Company has no intent to sell the U.S. Treasuries until a recovery of the fair value, which may be at maturity, and there are no current requirements to sell any of these securities, as of December 31, 2018, the Company did not consider these investments to be other-than-temporarily impaired. The Company anticipates full recovery of amortized costs with respect to these investments at maturity. The duration of time the U.S. Treasuries have been in a continuous unrealized loss position as of December 31, 2018 was less than 12 months.

The estimated fair values of available-for-sale securities at December 31, 2018, by contractual maturity, are summarized as follows:


	2018
Due in one year or less	$	10,380,864
Due after one year but within two years		5,008,243

	$	15,389,107