|9 Months Ended
Sep. 30, 2019
2. Stock Plans
In January 2019, our stockholders approved an amendment to the Titan Pharmaceuticals, Inc. 2015 Omnibus Equity Incentive Plan to increase the number of shares authorized for awards thereunder from 583,334 to 1,666,667.
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 $136,000 of additional stock-based compensation expense during the nine months ended September 30, 2019, of which approximately $77,000 was recorded within research and development and approximately $59,000 within selling, general and administrative in our condensed statement of operations and comprehensive loss.
The following table summarizes the stock-based compensation expense recorded for awards under our stock option plans (in thousands):
We use the Black-Scholes-Merton option-pricing model with the following assumptions to estimate the fair value of our stock options:
The following table summarizes option activity:
As of September 30, 2019, there was approximately $0.3 million of total unrecognized compensation expense related to non-vested stock options. This expense was expected to be recognized over a weighted-average period of approximately 1.7 years.