4.  Stock-Based Compensation

As of December 31, 2019, an aggregate of 3,783,114 shares of common stock were authorized under the Company’s 2019 Stock Incentive Plan (the “2019 Plan”), subject to an “evergreen” provision that will automatically increase the maximum number of shares of common stock that may be issued under the term of the 2019 Plan. As of December 31, 2019,  744,362 common shares were available for future grants under the 2019 Plan. As of December 31, 2019, 291,667 shares of common stock were authorized under the Company’s 2016 Consolidated Stock Incentive Plan (the “2016 Plan”) and 147,041 common shares were available for future grants under the 2016 Plan.

Stock Options

Below is a table summarizing the options issued and outstanding as of and for the three months ended December 31, 2019:

As of December 31, 2019, unrecognized compensation costs of associated with the stock options $6.0 million will be recognized over an estimated weighted-average amortization period of 1.5 years.

The weighted average grant date fair value of options granted during the three months December 31, 2019 was $4.78.

Key assumptions used to estimate the fair value of the stock options granted during the three months ended December 31, 2019 included:

Restricted Stock

A summary of the changes in the unvested restricted stock during the three months ended December 31, 2019 is as follows:

The Company recorded stock-based compensation expense in the following expense categories of its condensed consolidated statements of operations for the three months ended December 31, 2019 and 2018: