3. INVESTMENTS

The Company invests its excess cash in fixed income instruments denominated and payable in U.S. dollars including U.S. treasury securities, commercial paper, corporate debt securities and asset-backed securities in accordance with the Company’s investment policy that primarily seeks to maintain adequate liquidity and preserve capital.

The Company has designated all investments as available-for-sale and therefore such investments are reported at fair value. Unrealized gains or losses on investments are recorded in accumulated other comprehensive income or loss, a component of stockholders’ equity (deficit), on the Company’s condensed consolidated balance sheets.

The following table summarizes the Company’s investments, which are included in cash equivalents and short-term investments, as of September 30, 2018 and December 31, 2017:

As of September 30, 2018	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market mutual funds	$	11,441,399	$	—	$	—		$	11,441,399
Asset-backed securities		19,485,610		367		(3,543	)		19,482,434
Commercial paper		98,181,285		—		—			98,181,285
Corporate debt securities		54,428,208		6,772		(11,505	)		54,423,475
U.S. Treasury securities		54,440,052		—		(12,969	)		54,427,083
Total	$	237,976,554	$	7,139	$	(28,017	)	$	237,955,676

As of December 31, 2017	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market mutual funds	$	44,181,756	$	—	$	—		$	44,181,756
Asset-backed securities		7,428,021		—		(6,318	)		7,421,703
Commercial paper		34,882,298		—		—			34,882,298
Corporate debt securities		26,905,815		—		(49,532	)		26,856,283
U.S. Treasury securities		8,940,778		—		(17,458	)		8,923,320
Total	$	122,338,668	$	—	$	(73,308	)	$	122,265,360

As of September 30, 2018, the Company does not consider those securities that are in an unrealized loss position to be other-than-temporarily impaired, as it has the ability to hold such investments until recovery of the fair value. The Company utilizes the specific identification method in computing realized gains and losses. The Company had no realized gains and losses on its available-for-sale securities for the three and nine months ended September 30, 2018 and 2017. The contractual maturity dates of all of the Company’s investments are less than one year.