10. Stockholders’ equity:

Stock-based compensation

During the six months ended June 30, 2018, a total of 1,643,296 options to purchase Common Stock, with an aggregate fair market value of approximately $2.4 million, were granted to Company employees. Options granted to employees have a term of 10 years from the grant date and vest ratably over a three-year period. The fair value of each option is amortized as compensation expense evenly through the vesting period.

The Company’s stock-based compensation expense is allocated between research and development and selling, general and administrative as follows:


	Three months ended,				Six months ended,
Stock-based compensation expense	June 30, 2018		June 30, 2017		June 30, 2018		June 30, 2017
Research and Development	$	0.03	$	0.4	$	1.1	$	0.8
Selling, General and Administrative	$	1.1	$	2.5	$	2.9	$	5.2

The fair value of each option award is estimated on the grant date using the Black-Scholes valuation model that uses assumptions for expected volatility, expected dividends, expected term, and the risk-free interest rate. Expected volatilities are based on implied volatilities from historical volatility of the Common Stock, and other factors estimated over the expected term of the options.

Expected term of options granted is derived using the “simplified method” which computes expected term as the average of the sum of the vesting term plus contract term. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for the period of the expected term.

The key assumptions used in determining the fair value of options granted during the six months ended June 30, 2018 follows:


Expected price volatility		60.34%-68.77%
Risk-free interest rate		2.05%-2.82%
Weighted average expected life in years		6 years
Dividend yield		—

Option activity during the six months ended June 30, 2018 was as follows:


	Number of shares			Weighted average exercise price per share		Aggregate intrinsic value
Outstanding at January 1, 2018		2,712,954		$	3.68	$	1,190

Granted in 2018:
Officers and Directors		800,000			2.18
Employees		843,296			2.40
Exercised		(196,541	)		1.99
Forfeitures		(327,428	)		3.57

Outstanding at June 30, 2018		3,832,281		$	3.18	$	1,920

As of June 30, 2018, options exercisable totaled 1,767,831. There was approximately $5.2 million of unrecognized compensation cost related to non-vested share-based compensation awards, including options and restricted stock units (“RSUs”) granted. These costs will be expensed through 2021.

Restricted stock units

During the six months ended June 30, 2018, 1,410,611 RSUs were granted to the Company’s executive officers, employees and directors, with a fair market value of approximately $3.1 million. The fair value of restricted units is determined using quoted market prices of the Common Stock and the number of shares expected to vest. These RSUs were issued under the Company’s 2011 Equity Incentive Plan, as amended (the “EIP”).

RSU grants are either time-based or performance-based, all of which generally vest over a three-year period. Performance-based RSUs vest if specified predetermined net revenue and operating income goals are achieved. Actual performance relative to the predetermined performance measures are evaluated independently at the end of each fiscal year and the number of awards that will vest will be based upon the percentage of the individual performance measure achieved relative to the predetermined target. This allows for partial vesting relative to separate performance measures.

Restricted stock activity during the six months ended June 30, 2018 was as follows:


	Number of restricted shares			Weighted average fair market value per RSU
Outstanding at January 1, 2018		4,706,895		$	5.20
Granted:
Executive officers		1,038,434			2.23
Directors		55,000			1.95
Employees		317,177			2.10
Vested		(1,266,433	)		2.38
Forfeitures		(319,691	)		2.48
Conversions		(2,119,925	)		2.72

Outstanding at June 30, 2018		2,411,457		$	8.02

Series B Preferred Stock Financing

On May 17, 2018, the Company entered into a placement agency agreement with William Blair & Company, L.L.C., as placement agent, relating to the Company’s registered direct offering, issuance and sale of an aggregate of 5,000 shares of the Company’s authorized preferred stock that the Board of Directors of the Company has designated as Series B Non-Voting Convertible Preferred Stock, par value $.001 per share (the “Series B Preferred Stock”). All of the shares were sold by the Company. The placement agency agreement contains customary representations, warranties and covenants of the Company and the Placement Agent. The closing of the offering was completed on May 21, 2018. The shares sold in the offering were issued pursuant to a shelf registration statement, as amended, that the Company filed with the SEC, which became effective on July 13, 2015.

Each share of Series B Preferred Stock is convertible into a number of shares of the Company’s common stock, par value $.001 per share determined by dividing $10,000 by a conversion price of $1.80 per share (subject to adjustment for stock splits and stock dividends as provided in the Certificate of Designation) at any time following stockholder approval, which occurred at the annual shareholder meeting on August 2, 2018. As of the closing, the aggregate outstanding shares of Series B Preferred Stock will be convertible (upon stockholder approval) into an aggregate 27,777,778 shares of Common Stock. The Series B Preferred Stock does not contain any price-based anti-dilution protection. The Series B Preferred Stock is convertible at any time after stockholder approval at the option of the holder, except that a holder will be prohibited from converting shares of Series B Preferred Stock into shares of Common Stock if, as a result of such conversion, such holder, together with its affiliates, would beneficially own more than 9.98% of the total number of shares of Common Stock then issued and outstanding, which percentage may be increased or decreased on sixty-one (61) days’ notice from the holder of Series B Preferred Stock to the Company provided that, until stockholder approval, such beneficial ownership limitation may only be increased to up to 19.99% of the total number of shares of Common Stock then issued and outstanding.

Within ten (10) days following the date of stockholder approval, the Company has the right to deliver a notice to the holders of the Series B Preferred Stock to require conversion of the Series B Preferred Stock into Common Stock, provided that certain conditions with respect to the Common Stock are satisfied. Such forced conversion shall be subject to a holder’s beneficial ownership limitation of 9.98% of the total number of shares of Common Stock then issued and outstanding. Following an initial forced conversion of the Series B Preferred Stock, every ninety (90) days thereafter, the Company has the right to require the forced conversion of the still outstanding shares of Series B Preferred Stock up to the beneficial ownership limitation of 9.98% of the total number of shares of Common Stock then issued and outstanding.

Warrants

The Company has granted warrants to purchase shares of Common Stock.

The fair value of each warrant grant is estimated on the grant date using the Black-Scholes valuation model that uses assumptions for expected volatility, expected dividends, expected term, and the risk-free interest rate. Expected volatilities are based on implied volatilities from historical volatility of the Common Stock, and other factors estimated over the expected term of the warrants.

Expected term of warrants granted is derived using the “simplified method” which computes expected term as the average of the sum of the vesting term plus contract term. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for the period of the expected term. A cumulative total of 2,136,020 shares underlying warrants to purchase Common Stock are outstanding as of June 30, 2018 with a weighted average exercise price of $2.60 per share.