NOTE 8 —Stock-based Compensation

As of March 31, 2019, the Company had the 2012 Equity Incentive Plan (the “Option Plan”) in place. As of March 31, 2019, the number of shares available to be issued under the Option Plan was 459,075.

The Option Plan provides for the grant of incentive and nonstatutory stock options (“Options”), stock appreciation rights (“SAR”), restricted stock awards (“RSA”), and restricted stock unit awards (“RSU”) to employees, nonemployee directors, and consultants of the Company. Awards granted under the Option Plan generally becomes exercisable ratably over a two-year or four-year period following the date of grant and expire ten years from the date of grant. At the discretion of the Company’s Board of Directors, certain awards may be exercisable immediately at the date of grant but are subject to a repurchase right, under which the Company may buy back any unvested shares at their original exercise price in the event of an employee’s termination prior to full vesting. All other awards are exercisable only to the extent vested. At March 31, 2019 and December 31, 2018, there were no shares that had been early exercised that were subject to the Company’s repurchase right at that date. The exercise price or strike price for Options and SARs granted under the Option Plan must generally be at least equal to 100% of the fair value of the Company’s common stock at the date of grant, as determined by the Board of Directors. The exercise price of incentive stock options granted under the Option Plan to ten percent stockholders must be at least equal to 110% of the fair value of the Company’s common stock at the date of grant, as determined by the Board of Directors, and are not exercisable after five years from the date of grant.

Stock-based compensation expense for the three months ended March 31, 2019 and 2018 is as follows:

Stock Options:

Stock option activity for the three months ended March 31, 2019 is as follows:

As of March 31, 2019, there was approximately $707 of unamortized stock-based compensation cost related to unvested stock options, which is expected to be recognized over a weighted average period of three years.