v3.23.1
Note 9 - Stock-based Compensation
 3 Months Ended
Mar. 31, 2023
Notes to Financial Statements  
Share-Based Payment Arrangement [Text Block]

9. Stock-Based Compensation

 

The Company recorded total stock-based compensation expense for stock options, restricted stock units, or RSUs, and the Amended and Restated 2011 Employee Stock Purchase Plan, or the Amended ESPP, as follows (in thousands):

 

  

March 31, 2023

  

March 31, 2022

 

Research and development

 $93  $174 

Selling, general and administrative

  457   464 

Discontinued operations

  19   145 

Total

 $569  $783 

 

The following table summarizes restricted stock unit activity under the Company’s equity incentive plans:

 

      

Weighted

 
  

Number of

  

Average

 
  

Restricted

  

Grant Date

 
  

Stock Units

  

Fair Value

 

Restricted stock units outstanding, January 1, 2023

  82,778  $16.97 

Granted

  44,091   1.76 

Vested

  (34,606)  21.61 

Forfeited

  (643)  17.91 

Restricted stock units outstanding, March 31, 2023

  91,620  $7.89 

 

Upon vesting, certain of the Company’s RSUs may be settled on a net-exercise basis to cover any required withholding tax with the remaining amount converted into an equivalent number of shares of common stock. There were 12,906 shares of common stock underlying vested RSUs that were withheld during the quarter ended March 31, 2023, based on the value of the RSUs as determined by the Company’s closing stock price on the applicable vesting date.

 

The following table summarizes stock option activity under the Company’s equity incentive plans:

 

  

Number
of Stock Options
Outstanding

  

Weighted-
Average
Exercise
Price

  

Weighted-
Average
Remaining
Contractual
Life (Years)

  

Aggregate
Intrinsic
Value

 
              

(in thousands)

 

January 1, 2023

  725,623  $52.98         

Granted

  264,520   1.76         

Forfeited

  (1,950)  19.41         

Expired

  (90,802)  83.75         

Exercised

  —   —         

March 31, 2023

  897,391  $34.84   6.9  $— 

Vested and exercisable options— March 31, 2023

  459,397  $58.42   4.7  $— 

Vested and expected to vest— March 31, 2023

  897,391  $34.84   6.9  $— 

 

The per-share weighted average grant date fair value of the options granted during the quarter ended March 31, 2023 was estimated at $1.39 per share on the date of grant using the Black-Scholes option-pricing model with the following weighted average assumptions:

 

  

Three months ended

March 31, 2023

 

Expected term (in years)

  6.3 

Risk-free interest rate

  3.9% 

Expected volatility

  94% 

Expected dividend rate

  0% 

 

As of March 31, 2023, total stock-based compensation expense related to unvested options to be recognized in future periods was $1.7 million which is expected to be recognized over a weighted-average period of 2.2 years. As of March 31, 2023, there were 127,611 shares available for grant under the Company’s equity incentive plans and 185,860 shares available for grant under the Amended ESPP.