PRSS 2017 Annual Report

61 Stock option activity The following table summarizes stock option activity related to shares of common stock (in thousands, except weighted average exercise price): Number of stock options outstanding Weighted- average exercise price Weighted- average remaining contractual life (years) Aggregate intrinsic value Outstanding—December 31, 2016 2,147 $ 4.79 6.35 $ 8 Granted 604 2.90 Exercised (6) 2.12 Forfeited (475) 6.24 Outstanding—December 31, 2017 2,270 $ 3.99 6.81 $ — Options vested and expected to vest—December 31, 2017 2,270 $ 3.99 6.81 $ — Options exercisable—December 31, 2017 905 $ 4.83 5.05 $ — The total intrinsic value of options exercised during the years ended December 31, 2017 and 2016 was $0.0 million and $0.1 million, respectively. The following table summarizes information regarding stock options outstanding at December 31, 2017: Options outstanding Options vested and exercisable Exercise prices Number of stock options outstanding Weighted average remaining contractual life (years) Weighted average exercise price per share Shares subject to stock options Weighted average exercise price per share (in thousands) (in thousands) $2.08-$3.08 230 9.13 $ 2.50 15 $ 3.08 $3.09-$3.09 92 8.84 $ 3.09 25 $ 3.09 $3.13-$3.13 470 9.19 $ 3.13 88 $ 3.13 $3.25-$3.27 254 8.33 $ 3.26 68 $ 3.26 $3.74-$3.74 257 8.00 $ 3.74 — $ — $4.14-$4.14 147 7.38 $ 4.14 95 $ 4.14 $4.30-$4.30 267 4.37 $ 4.30 172 $ 4.30 $4.66-$4.66 103 4.86 $ 4.66 54 $ 4.66 $5.07-$5.07 247 3.59 $ 5.07 206 $ 5.07 $5.58-$18.80 203 2.07 $ 7.08 182 $ 7.26 $2.08-$18.80 2,270 6.81 $ 3.99 905 $ 4.83 Included in the stock options outstanding as of December 31, 2017 are 380,632 non-statutory stock options that have both three- year service criteria and vesting contingent on financial performance measures at the end of a three-year performance period ending December 31, 2018. The performance criteria for these awards consist of the following financial measures during the performance period: (i) revenue during each period, (ii) cumulative Adjusted EBITDA; and (iii) cumulative free cash flow, which we define as cash flows from operations minus capital expenditures. Compensation cost associated with these performance-based stock options is recognized using an attribution model and ultimately based on whether or not satisfaction of the performance criteria is probable. The total compensation cost we recognize under these option awards will be based upon the results of the financial measures. As of December 31, 2017, we have estimated that it is not probable that the performance criteria will be met and, accordingly, no stock compensation expense for the performance shares has been recorded. At December 31, 2017, we had $0.8 million of unrecognized compensation expense related to these performance awards.