8. Stock-Based Compensation

As of March 31, 2020, the Company had 149,022 options to purchase common stock outstanding.

In June 2013, the Company’s shareholders voted to approve the Rexahn Pharmaceuticals, Inc. 2013 Stock Option Plan (the “2013 Plan”).  Under the 2013 Plan, the Company grants equity awards to key employees, directors and consultants of the Company.  The Company has reserved 283,333 shares of common stock for issuance pursuant to the 2013 Plan. As of March 31, 2020, there were 144,366 options outstanding under the 2013 Plan, and 136,936 shares were available for issuance.  In addition, as of March 31, 2020, there were 4,656 options outstanding under a previously established stock option plan under which no new stock options may be granted. 

Accounting for Awards

Stock-based compensation expense is the estimated fair value of options granted amortized on a straight-line basis over the requisite vesting service period for the entire portion of the award. Total stock-based compensation recognized by the Company for the three months ended March 31, 2020 and 2019 is as follows:





No income tax benefit has been recognized in the statement of operations for stock-based compensation arrangements as the Company has provided for a 100% valuation allowance on its deferred tax assets.

Summary of Stock Option Transactions



A summary of stock option activity for the three months ended March 31, 2020 is as follows:





A summary of the Company’s unvested options as of March 31, 2020 and changes during the three months ended March 31, 2020 is presented below:



As of March 31, 2020, there was $501,655 of total unrecognized compensation cost related to unvested stock options, which is expected to be recognized over a weighted average vesting period of 1.7 years.