Fair Value Measurements

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

The following table presents the Company’s assets and liabilities that are measured and recognized at fair value on a recurring basis classified under the appropriate level of the fair value hierarchy as of December 31, 2016 and 2015:

	Fair Value Measurements at December 31, 2016
	Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market fund (1)	$	12,095,620	$	—	$	—	$	12,095,620
Corporate debt securities (2)	—		14,160,686		—		14,160,686
Commercial paper (3)	—		2,393,948		—		2,393,948
U.S. treasury securities (2)	—		8,621,892		—		8,621,892
Total Assets	$	12,095,620	$	25,176,526	$	—	$	37,272,146
Liabilities:
Derivative financial instruments—warrants	$	—	$	—	$	834,940	$	834,940
Total Liabilities	$	—	$	—	$	834,940	$	834,940

	Fair Value Measurements at December 31, 2015
	Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market fund (1)	$	65,016,222	$	—	$	—	$	65,016,222
Total Assets	$	65,016,222	$	—	$	—	$	65,016,222
Liabilities:
Derivative financial instruments—warrants	$	—	$	—	$	3,297,077	$	3,297,077
Total Liabilities	$	—	$	—	$	3,297,077	$	3,297,077

(1)Included as a component of cash and cash equivalents on the accompanying consolidated balance sheet.

(2)Included in short-term investments on the accompanying consolidated balance sheet.

(3)$1,198,504 of commercial paper was included as a component of cash and cash equivalents, and the rest of amount was included in short-term investments on the accompanying consolidated balance sheet.

The following table sets forth a summary of changes in the fair value of the Company’s Level 3 liabilities for the years ended December 31, 2016 and 2015:

Description	Balance at December 31, 2015		Unrealized (gains) or losses			Balance at December 31, 2016
Derivative financial instruments—Warrants	$	3,297,077	$	(2,462,137	)	$	834,940

Description	Balance at December 31, 2014		Fair Value of Warrants Reclassified to Additional Paid-in Capital			Unrealized (gains) or losses		Balance at December 31, 2015
Derivative financial instruments—Warrants	$	3,006,021	$	(435,365	)	$	726,421	$	3,297,077

The unrealized gains or losses on the derivative financial instruments—warrants are recorded as a change in fair value of derivative financial instruments—warrants in the Company’s consolidated statement of operations. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. At each reporting period, the Company reviews the assets and liabilities that are subject to ASC Topic 815-40. At each reporting period, all assets and liabilities for which the fair value measurement is based on significant unobservable inputs or instruments that trade infrequently and therefore have little or no price transparency are classified as Level 3.