The Company has adopted the 2019 Plan, which allows for the grant of stock options, stock appreciation rights and stock awards for a total of 3,000,000 shares of common stock. On December 1^st of each year, pursuant to the “Evergreen” provision of the 2019 Plan, the number of shares available under the plan shall be increased by an amount equal to 5% of the outstanding common stock on December 1^st of that year or such lower amount as determined by the Board of Directors. In December 2019, the number of shares available for issuance under the 2019 Plan was increased by 467,535. The total number of shares authorized for issuance under the 2019 plan as of September 30, 2020 is 3,467,535. As of September 30, 2020, 1,076,396 shares are available for future grants under the 2019 Plan.

Stock Options:

Stock options are exercisable generally for a period of 10 years from the date of grant and generally vest over four years. The weighted average grant-date fair value of the Baudax Bio options awarded to employees during nine months ended September 30, 2020 was $2.22. Under the 2019 Plan, the fair value of the Baudax Bio options was estimated on the date of grant using a Black-Scholes option pricing model with the following weighted average assumptions:

Certain employees of the Company participated in the Recro Equity Plan. The combined financial statements prior to the Separation reflect stock-based compensation expense related to Recro stock options and RSUs issued to the Company’s employees as well as an allocation of a portion of Recro share-based compensation issued to corporate employees and members of the Board of Directors until the Separation date. The weighted average grant-date fair value of the options awarded to employees under the Recro Equity Plan during the nine months ended September 30, 2019 was $5.53.

Under the Recro Equity Plan for the nine months ended September 30, 2019, the fair value of the options granted to employees of the Company was estimated on the date of grant using a Black-Scholes option pricing model with the following weighted average assumptions:

The following table summarizes Baudax Bio stock option activity during the nine months ended September 30, 2020:

Included in the table above are 634,503 stock options outstanding as of September 30, 2020 that were granted outside of the plan. The grants were made pursuant to the Nasdaq inducement grant exception in accordance with Nasdaq Listing Rule 5635(c)(4).

Restricted Stock Units (RSUs):

The following table summarizes the Baudax Bio RSUs activity during the nine months ended September 30, 2020:

Included in the table above are 176,307 time-based RSUs outstanding as of September 30, 2020 that were granted outside of the plan. The grants were made pursuant to the Nasdaq inducement grant exception in accordance with Nasdaq Listing Rule 5635(c)(4).

Stock-Based Compensation Expense:

Stock-based compensation expense for the nine months ended September 30, 2020 and 2019 was $7,431 and $4,254, respectively. For the current year, this represents stock-based compensation from the 2019 Plan as well as stock-based compensation from the Recro Equity Plan for certain Baudax Bio employees who are continuing to vest in their Recro awards but are not performing services to Recro. For the prior year, this represents the allocated portion of Recro stock-based compensation expense for employees of the Company.

As of September 30, 2020, there was $10,720 of unrecognized compensation expense related to unvested options and time-based RSUs that are expected to vest and will be expensed over a weighted average period of 2.6 years, which includes stock-based compensation from the 2019 Plan as well as the Recro Equity Plan for certain employees of the Company.

The aggregate intrinsic value represents the total amount by which the fair value of the common stock subject to options exceeds the exercise price of the related options. As of September 30, 2020, the aggregate intrinsic value of the unvested options was $66. There was no aggregate intrinsic value of the vested options.