STOCKHOLDERS’ DEFICIT

Stock Options

The fair value for options granted at the time of issuance were estimated at the date of grant using a Black-Scholes options pricing model. Significant assumptions included in the option value model include the fair value of our common stock at the grant date, weighted average volatility, risk-free interest rate, dividend yield and the forfeiture rate. There were no stock options granted in any of the periods presented.

Our stock option activity and related information are summarized as follows:



			Weighted-Average		Contractual Terms
	Options		Exercise Price		(in Years)
Outstanding at January 1, 2017	248,201		$	23.81	2.4
Forfeited or expired	(70,438	)	$	9.82
Outstanding at September 30, 2017	177,763		$	29.34	2.3

Options generally include a time-based vesting schedule permitting the options to vest ratably over three years. At September 30, 2017 and December 31, 2016, all options were fully vested.

There was no stock-based compensation expense on stock options for all periods ended September 30, 2017 and 2016, respectively.

Restricted Stock

Our restricted stock activity and related information are summarized as follows:



			Weighted-Average
			Remaining
	Restricted		Contractual Terms
	Stock		(in Years)
Outstanding at January 1, 2017	677,242		3.5
Granted	79,261
Forfeited	(13,223	)
Vested	(38,510	)
Outstanding at September 30, 2017	704,770		3.2
Restricted stock exercisable at September 30, 2017	—

At September 30, 2017, there was $4,346 of unrecognized compensation expense remaining related to our service-based restricted stock awards. The unrecognized compensation cost was expected to be recognized over a weighted average period of 3.2 years or earlier upon an elimination of the restriction period as a result of an initial public offering or change in control event.

Stock-based compensation expense on restricted stock amounted to $354 and $300 for the three months ended and $1,081 and $950 for the nine months ended September 30, 2017 and 2016, respectively. Due to our limited operating history and lack of marketability, a discount of 15% was applied when estimating the stock-based compensation expense on restricted stock in 2017.

Total stock-based compensation expense is included as a component of general and administrative expenses in our statement of operations and was $354 and $300 for the three months ended and $1,081 and $950 for the nine months ended September 30, 2017 and 2016, respectively.

Warrants

For all periods presented, there were warrants issued and outstanding for the issuance of 44,101 shares of common stock. The warrants were issued at exercise prices ranging from $26.27 to $30.97 per share. The warrants generally have a ten-year term. At September 30, 2017, no warrants had been exercised. At inception, no fair value was assigned to the warrants.