Share-Based Compensation Plans | Note H - Share-based Compensation Plans We primarily use the Black-Scholes option pricing model to value stock options granted to employees and non-employees, including stock options granted to members of our Board of Directors. All stock options have 10-year terms and generally vest ratably over a 3 or 4-year period. A non-cash charge to operations for the stock options granted to non-employees that have vesting or other performance criteria is affected each reporting period, until the non-employee options vest, by changes in the fair value of our common stock. A summary of option activity for the nine months ended September 30, 2016 is presented below: Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value Outstanding at December 31, 2015 8,345,835 $ 4.77 Granted 4,252,739 4.26 Exercised (198,636 ) 3.31 Forfeited (452,604 ) 5.03 Expired (185,780 ) 8.75 Outstanding at September 30, 2016 11,761,554 $ 4.53 7.70 $ 32,843,626 Vested or expected to vest at September 30, 2016 10,599,495 $ 4.55 7.57 $ 29,971,443 Exercisable at September 30, 2016 5,624,490 $ 4.68 6.23 $ 15,941,877 The weighted average grant-date fair values of stock options granted during the nine months ended September 30, 2016 and 2015 were $2.38 and $3.85, respectively. As of September 30, 2016, $11.4 million of total unrecognized compensation cost related to stock options granted to employees and directors is expected to be recognized over a weighted average period of 2.4 years. As of September 30, 2016, unrecognized expense for options granted to outside advisors for which performance (vesting) has not yet been completed but the exercise price of the option is known is $308,000. Such amount is subject to change each reporting period based upon changes in the fair value of our common stock, expected volatility, and the risk-free interest rate, until the outside advisor completes his or her performance under the option agreement. Certain employees and consultants have been granted nonvested stock. The fair value of nonvested stock is calculated based on the closing sale price of our common stock on the date of issuance. A summary of nonvested stock activity for the nine months ended September 30, 2016 is presented below: Nonvested Shares Weighted Average Grant Fair Value Outstanding at December 31, 2015 1,730,604 $ 8.55 Granted 935,438 2.91 Vested (570,037 ) 8.52 Forfeited (158,982 ) 8.05 Outstanding at September 30, 2016 1,937,023 $ 6.51 As of September 30, 2016, there was approximately $10.4 million of unrecognized share-based compensation expense related to these nonvested shares awarded to employees which pertained primarily to performance based awards for which, if all milestones are achieved, will be recognized over a 1.6 year period. The total intrinsic value of shares vested during the nine months ended September 30, 2016, was $2.4 million. During the nine months ended September 30, 2016, 121,228 shares were issued under the 2009 Employee Stock Purchase Plan, 570,037 shares were issued as a result of the vesting of nonvested stock and 198,636 shares were issued as a result of stock option exercises. The impact on our results of operations from share-based compensation for the three and nine months ended September 30, 2016 and 2015, was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Research and development $ 818 $ 453 $ 3,689 $ 1,695 General and administrative 1,565 320 5,012 3,523 Total share-based compensation expense $ 2,383 $ 773 $ 8,701 $ 5,218 |