The fair value of each option grant on the date of grant is estimated using the Black-Scholes option-pricing model.  On the date of grant, the following weighted average assumptions were utilized for options granted during the three and six months ended June 30, 2015 and 2014.

The following table presents information relating to all stock options outstanding and exercisable at June 30, 2015:

During the six month period ended June 30, 2015, the Company granted 5-year stock options to each of its three non-management directors to purchase 35,000 shares of its common stock at an exercise price of $2.34 per share.  Such options vest over a one-year period in four equal quarterly amounts beginning on April 22, 2015, subject to continued service on the Board.

The Company recorded stock-based compensation of $74,000 and $135,000 for the three months ended June 30, 2015 and June 30, 2014, respectively.  The Company recorded stock-based compensation of $174,000 and $162,000 for the six months ended June 30, 2015 and June 30, 2014, respectively.  The Company has an aggregate of $99,000 of unrecognized stock-based compensation cost as of June 30, 2015.  The aggregate intrinsic value of options exercisable at June 30, 2015 was $1,167,985.

During the three month period ended June 30, 2015, the Company’s Executive Vice President exercised a stock option to purchase 150,000 shares of the Company’s common stock at an exercise price of $0.90 per share.  The option was exercised on a cashless (net exercise) basis by delivery to the Company of 60,000 shares of common stock resulting in 90,000 net shares issued to the Company’s Executive Vice President with respect to such option exercise.  In addition, during the three month period ended June 30, 2015, a consultant to the Company exercised a stock option to purchase 50,000 shares of the Company’s common stock at an exercise price of $0.90 per share.  The option was exercised on a cashless (net exercise) basis by delivery to the Company of 19,651 shares of common stock resulting in 30,349 net shares issued to the consultant with respect to such option exercise.

During the three month period ended June 30, 2014, the Company’s Chairman and Chief Executive Officer exercised stock options to purchase an aggregate of 1,517,500 shares of common stock at exercise prices of $0.25 per share (1,100,000 shares) and $0.68 per share (417,500 shares).  All such shares were exercised on a cashless (net exercise) basis by delivery of an aggregate of 292,618 shares of common stock.  In addition, the Chairman and Chief Executive Officer delivered an aggregate of 516,288 shares of common stock with an aggregate value of $986,110 to fund payroll withholding taxes with respect to such option exercises.  As a result of the aforementioned stock option exercises, the Chairman and Chief Executive Officer received 708,594 net shares of the Company’s common stock.

During the six month period ended June 30, 2014, the Company’s Executive Vice President exercised a stock option to purchase 75,000 shares of the Company’s common stock at an exercise price of $0.68 per share.  The option was exercised on a net exercise (cashless) basis by delivery to the Company of 31,098 shares of common stock.  In addition, 16,968 shares were delivered to the

Company with an aggregate value of $28,000 to fund payroll withholding taxes on exercise, resulting in net shares of 26,934 issued to the Company’s Executive Vice President with respect to such option exercise.

As of June 30, 2015, the following are the outstanding warrants to purchase shares of the Company’s common stock:

All of the aforementioned warrants were issued to Recognition Interface, LLC in connection with the Company’s acquisition of the Mirror Worlds Patent Portfolio (see Note J[2]).