Stock Incentive Plans |
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Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stock Incentive Plans | 14. STOCK INCENTIVE PLANS Stock Options and Restricted Stock Units (“RSU”) The following table summarizes option and unvested RSU activity under the Company’s 2014 Equity Incentive Plan and 2016 Inducement Plan and related information:
The total intrinsic value of options exercised was $2.6 million in the nine months ended September 30, 2018. As of September 30, 2018, the total intrinsic value of outstanding RSUs was approximately $3.0 million and there were $6.6 million of unrecognized compensation costs related to RSUs, which are expected to be recognized over a weighted-average period of 3.19 years. As of September 30, 2018, the total intrinsic value of outstanding options was approximately $51.1 million and there were $6.4 million of unrecognized compensation costs related to options, which are expected to be recognized over a weighted-average period of 3.20 years. Options outstanding that have vested and are expected to vest at September 30, 2018 are as follows:
2014 Employee Stock Purchase Plan During the offering period in 2017 that ended on December 31, 2017, 34,176 shares were purchased for aggregate proceeds of $0.1 million from the issuance of shares, which occurred on January 4, 2018. During the offering period in 2018 that ended on June 30, 2018, 42,534 shares were purchased for aggregate proceeds of $0.3 million from the issuance of shares, which occurred on July 2, 2018. Valuation Assumptions The estimated fair value of employee stock options and ESPP shares were estimated using the Black Scholes option-pricing model based on the following weighted average assumptions:
Risk-free Interest Rate: The Company based the risk-free interest rate over the expected term of the award based on the constant maturity rate of U.S. Treasury securities with similar maturities as of the date of grant. Volatility: The Company used an average historical stock price volatility of its own stock and those comparable public companies that were deemed to be representative of future stock price trends. Expected Term: The expected term represents the period for which the Company’s stock-based compensation awards are expected to be outstanding and is based on analyzing the vesting and contractual terms of the awards and the holders’ historical exercise patterns and termination behavior. Expected Dividends: The Company has not paid and does not anticipate paying any dividends in the near future. Stock-based Compensation Expense The following table summarizes stock-based compensation expense relating to employee and nonemployee stock options, RSUs and ESPP shares for the three and nine months ended September 30, 2018 and 2017, included in the statements of operations as follows (in thousands):
No tax benefit was recognized related to share-based compensation expense since the Company has never reported taxable income and has established a full valuation allowance to offset all of the potential tax benefits associated with its deferred tax assets. In addition, no amounts of stock-based compensation expense were capitalized for the periods presented. |