On July 23, 2014, Company stockholders approved the Amended 2013 Plan, which provides for the granting of stock options, restricted stock awards, restricted stock units, stock bonus awards and performance-based awards. The Amended 2013 Plan serves as the successor to the 2013 Equity Incentive Plan. There were no option awards under the 2013 Equity Incentive Plan. Under the Amended 2013 Plan, the Company may grant up to 10,000,000 shares of new stock. As of June 30, 2015, the Company had approximately 3,250,556 of authorized unissued shares reserved and available for issuance.

The stock options are exercisable at no less than the fair market value of the underlying shares on the date of grant, and restricted stock and restricted stock units are issued at a value not less than the fair market value of the common stock on the date of the grant. Generally, stock options awarded are vested in equal increments ranging from two to four years on the annual anniversary date on which such equity grants were awarded. The stock options generally have a maximum term of 10 years. The following table summarizes stock option activity for the Amended 2013 Plan during the six months ended June 30, 2015:

The following table summarizes unvested stock options as of June 30, 2015:

The Company recognized expenses of $557,792 and $1,723,786 relating to stock options issued to employees, non-employees, officers, and directors during the three and six months ended June 30, 2015, respectively. The Company recognized expenses of $308,900 and $898,900 relating to common stock issued to employees, non-employees, officers, and directors during the three and six months ended June 30, 2015. For the three and six months ended June 30, 2015, stock-based compensation of $857,846 and $2,601,173, was expensed to selling, general and administration, respectively. For the three and six months ended June 30, 2015, stock-based compensation of $8,846 and $21,513, was expensed to research and development, respectively. As of June 30, 2015, total unrecognized compensation cost related to unvested stock-based compensation arrangements granted to employees, officers, and directors was $5,096,320, which is expected to be recognized over a weighted-average period of 2.14 years. There was no stock-based compensation expense for the three and six months ended June 30, 2014.