9. Stock Plans

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 1,666,667 shares of our common stock for issuance to employees, directors, officers, consultants and advisors. As of December 31, 2019, options to purchase 577,879 shares of our common stock were available for grant and 1,088,788 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 75,758 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, 2019, options to purchase 41,345 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 217,000 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, 2019, options to purchase an aggregate of 49,344 shares of our common stock were outstanding under the 2002 Plan.

In August 2001, we adopted the 2001 Employee Non-Qualified Stock Option Plan (the “2001 NQ Plan”) pursuant to which 53,031 shares of common stock were authorized for issuance for option grants to employees and consultants who are not officers or directors of Titan. The exercise prices of options granted under the 2001 NQ Plan were 100% of the fair market value of our common stock on the date of grant. The 2001 Stock Option Plan expired by its terms in August 2011. As of December 31, 2019, options to purchase an aggregate of 12,246 shares of our common stock were outstanding under the 2001 NQ Plan.

In January 2019, our stockholders approved a repricing of 122,115 fully-vested stock options with exercise prices in excess of $21.00 held by employees and consultants other than the named executive officers or members of the Board. The effected options were repriced at $1.55. As a result of the repricing of these stock options, we incurred a total of approximately $81,000 of additional stock-based compensation expense during the year ended December 31, 2019, of which approximately $54,000 was recorded within research and development and approximately $27,000 within selling, general and administrative in our statement of operations and comprehensive loss.

The following table summarizes option activity for the year ended December 31, 2019:

 

 

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

 

(3)Estimated forfeiture rates are based on historical data.

 

Based upon the above methodology, the weighted-average fair value of options and awards granted during the years ended December 31, 2019 and 2018 was $1.64 and  $3.21 , respectively.

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

 

 

As of December 31, 2019, there was approximately $0.3 million of total unrecognized compensation expense related to non-vested stock options. This expense is expected to be recognized over a weighted-average period of 1.5 years.