Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity

Stockholders' Equity

3 Months Ended

Mar. 31, 2018

9. Stockholders’ Equity

Shares issued

1,072,500 shares of common stock were issued during January 2018 upon exercise of the overallotment option related to the December 2017 public offering, netting proceeds to the Company of $2.1 million.

The Company issued 65,600 shares of common stock upon vesting of Restricted Stock Units during the three months ended March 31, 2018. Additionally, the Company issued 2,034 shares of common stock pursuant to the Officers and Directors Purchase Plan during the three months ended March 31, 2018 for proceeds of $4,000.

Stock based compensation

The stock-based compensation expense attributable to option grants was allocated as follows:

	Three months ended March 31,
	2018			2017
Cost of product sales	$	50		$	—
Research and development cost		112			87
General and administrative expense		(18	)		74
Total	$	144		$	161

The following assumptions were used in the Black-Scholes-Merton pricing model to estimate the fair value of options granted during the periods presented.

	Three months ended March 31,
	2018	2017

Expected stock volatility	78.4%-79.9%	70.9%-72.2%
Risk free interest rate	2.06%-2.45%	1.53%-1.79%
Expected years until exercise	3.5	3.5
Dividend yield	0%	0%

There were no stock option exercises during the three months ended March 31, 2018.