On June 16, 2016, the Company’s shareholders approved the 2016 Stock Incentive Plan, which authorizes the issuance of incentive stock options and non-qualified stock options, restricted stock, restricted stock units, stock appreciation rights, direct stock issuances and other stock-based awards to the Company’s officers, directors or key employees or to consultants that do business with the Company initially for up to an aggregate of 1,150,000 shares of common stock. On June 14, 2018, the Company’s shareholders approved an increase to the aggregate number of shares authorized under the 2016 Stock Incentive Plan to 3,650,000 shares. On November 7, 2019, the Company’s shareholders approved an increase to the aggregate number of shares authorized under the 2016 Stock Incentive Plan to 5,650,000 shares. On November 18, 2020, the Company’s shareholders approved an increase to the aggregate number of shares authorized under the 2016 Stock Incentive Plan to 7,400,000 shares. On June 23, 2022, the Company’s shareholders approved an increase to the aggregate number of shares authorized under the 2016 Stock Incentive Plan to 8,900,000 shares. On June 22, 2023, the Company’s shareholders approved an increase to the aggregate number of shares authorized under the 2016 Stock Incentive Plan to 11,400,000 shares.

Restricted Stock – A summary of unvested restricted stock activity is as follows (shares in thousands):

The fair value of the common stock at vesting aggregated $929,000, $6,900,000 and $8,810,000 for the years ended December 31, 2023, 2022 and 2021, respectively. Stock-based compensation expense related to employee and non-employee restricted stock and option grants recognized in the accompanying consolidated statements of operations, was as follows (in thousands):

Employee grants typically have a two or three-year vesting schedule, while non-employee grants have a one-year vesting schedule. At December 31, 2023, the total compensation expense related to unvested awards which had not been recognized was $8,281,000 and the associated weighted-average period over which the compensation expense attributable to those unvested awards will be recognized was approximately 0.67 years.