In August 2015, our stockholders approved the 2015 Omnibus Equity Incentive Plan (the “2015 Plan”). The 2015 Plan, as subsequently amended, authorized a total of 1,000,000 shares of our common stock for issuance to employees, directors, officers, consultants and advisors. As of December 31, 2022, options to purchase 74,262 shares of our common stock were available for grant and 925,738 shares of our common stock outstanding under the 2015 Plan.

In February 2014, our Board adopted the 2014 Incentive Plan (the “2014 Plan”), pursuant to which 2,526 shares of our common stock were authorized for issuance to employees, directors, officers, consultants and advisors. The 2014 Plan was terminated upon the approval of the 2015 Plan. As of December 31, 2022, options to purchase 1,189 shares of our common stock were outstanding under the 2014 Plan.

In July 2002, we adopted the 2002 Stock Incentive Plan (the “2002 Plan”). The 2002 Plan, as amended in 2005, authorized a total of approximately 7,234 shares of our common stock for issuance to employees, officers, directors, consultants, and advisers. The exercise prices of options granted under the 2002 Plan were 100% of the fair market value of our common stock on the date of grant. The 2002 Plan expired by its terms in July 2012. As of December 31, 2022, no options to purchase shares of our common stock were outstanding under the 2002 Plan.

The following table summarizes option activity for the year ended December 31, 2022:

We use the Black-Scholes-Merton option-pricing model with the following assumptions to estimate the stock-based compensation expense:

Based upon the above methodology, the weighted-average fair value of options and awards granted during the years ended December 31, 2022 and 2021 was $0.95 and $3.29, respectively.

The following table summarizes the stock-based compensation expense (in thousands):

As of December 31, 2022, there was approximately $0.8 million of total unrecognized compensation expense related to non-vested stock options subject to shareholder approval. This expense is expected to be recognized over a weighted-average period of approximately 0.7 year.

On August 2, 2022, our Board of Directors, or Board, modified the outstanding options to purchase common stock under our 2015 Omnibus Equity Incentive Plan, or 2015 Plan, to allow for the acceleration of vesting of all unvested 2015 Plan options in the event of a change in control through the election of a majority of new members to our Board.

On August 15, 2022, the Special Meeting was held at the request of Activist, to increase the size of our Board from five members to eleven members and elect Activist’s slate of six nominees to serve as directors in addition to the existing five Board members. As a result of the change of control, all unvested options granted under the 2015 Plan prior to August 15, 2022, immediately became vested. We recognized approximately $0.5 million of stock-based compensation related to the acceleration of vesting.

On August 15, 2022, our Board granted 125,000 options to purchase common stock at $1.52 per share which are subject to shareholder approval of an amendment to increase the number of shares reserved for issuance under our 2015 Plan. The options vest monthly over a 12-month period from the grant dates. As the shares underlying these options have not been approved by our stockholders, they have been excluded from the table above as of December 31, 2022. We have recognized approximately $60,000 of stock-based compensation related to these grants.

On September 15, 2022, our Board granted 900,000 options to purchase common stock at $1.31 per share which are subject to shareholder approval of an amendment to increase the number of shares reserved for issuance under our 2015 Plan. The options vest monthly over a 12-month period from the grant dates. As the shares underlying these options have not been approved by our stockholders, they have been excluded from the table above as of December 31, 2022. We have recognized approximately $250,000 of stock-based compensation related to these grants.