Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2015

Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table classifies the Company’s financial assets and liabilities measured at fair value on a recurring basis at September 30, 2015 and December 31, 2014, respectively into the fair value hierarchy:

	Balance at September 30, 2015
	Level 1		Level 2		Level 3		Total
Asset included in:
Cash and cash equivalents
Money market securities	$	2,573,882	$	—	$	—	$	2,573,882
Investments at fair value
U.S. government obligations	$	3,308,573	$	—	$	—	$	3,308,573
U.S. government agency obligations	$	—	$	14,715,616	$	—	$	14,715,616
Corporate debt securities	$	—	$	18,454,522	$	—	$	18,454,522

	Balance at December 31, 2014
	Level 1		Level 2		Level 3		Total
Asset included in:
Cash and cash equivalents
Money market securities	$	3,608,890	$	—			$	3,608,890
Liabilities included in:
Growth Term Loan warrants	$	—	$	—	$	301,508	$	301,508
Convertible Preferred Stock warrants	$	—	$	—	$	429,035	$	429,035

Summary of Fair Value Assessment of Warrant Liability Inputs using Black Sholes Option Pricing Model

The December 31, 2014 fair value assessments used the Black-Sholes option pricing model using the following assumptions:

	December 31, 2014
Fair value of Series B/C/D Stock and Series E Stock shares on grant date or measurement date	$0.14 - $0.22
Exercise price	$0.01 - $0.346
Expected risk-free interest rate		1.20%
Expected volatility		70%
Expected term	4.1 years
Expected dividend yield	0 - 8%

Reconciliation of Beginning and Ending Liabilities Measured at Fair Value on Recurring Basis

A reconciliation of the beginning and ending liabilities measured at fair value and classified as Level 3 inputs for the nine months ended September 30, 2015 and September 30, 2014 are as follows:

	September 30,
	2015			2014
Beginning balance	$	730,543		$	44,120
Issuance of Series E Convertible Preferred Stock Warrants		—			2,191,507
Exercise of Series E Convertible Preferred Stock Warrants		(4,116	)		(1,890,000	)
Exercise of Series D Convertible Preferred Stock Warrants		(91,798	)		—
Reclassification of Series C-2 Convertible Preferred Stock Warrants to Common Stock Warrants		(555	)		—
Reclassification of Growth Term Loan Warrants to Common Warrants		(229,550	)		—
Issuance of Convertible Note Warrants		741,828			—
Reclassification of Convertible Note Warrants to Common Stock Warrants		(1,386,035	)		—
Change in Convertible Preferred Stock warrant valuation		239,683			56,322
Ending balance	$	—		$	401,949