Quarterly report pursuant to Section 13 or 15(d)

Condensed Statement of Changes in Stockholders' Equity

v3.19.3
Condensed Statement of Changes in Stockholders' Equity - USD ($)
Total
Common Stock [Member]
Additional Paid-in Capital [Member]
Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2017 $ 11,758,730 $ 225 $ 185,659,954 $ (173,901,449)
Beginning balance (in shares) at Dec. 31, 2017   22,584,588    
Stock-based compensation - restricted stock units ("RSUs") 4,251,961   4,251,961  
Stock-based compensation - employee stock purchase plan ("ESPP") 154,545   154,545  
Stock-based compensation - performance share units ("PSUs") 202,702   202,702  
Issuance of shares for RSUs   $ 3 (3)  
Issuance of shares for RSUs (in shares)   341,936    
Issuance of shares for PSUs   $ 1 (1)  
Issuance of shares for PSUs (in shares)   80,098    
Exercise of stock options 981,053 $ 2 981,051  
Exercise of stock options (in shares)   179,732    
Cashless exercise of warrants (in shares)   7,989    
Proceeds from contributions to the ESPP 200,935   200,935  
Issuance of shares in an at-the-market ("ATM") offering, net of issuance costs 38,846,815 $ 22 38,846,793  
Issuance of shares in an at-the-market ("ATM") offering, net of issuance costs (in shares)   2,221,455    
Net loss (13,443,457)     (13,443,457)
Ending balance at Mar. 31, 2018 42,953,284 $ 253 230,297,937 (187,344,906)
Ending balance (in shares) at Mar. 31, 2018   25,415,798    
Beginning balance at Dec. 31, 2017 11,758,730 $ 225 185,659,954 (173,901,449)
Beginning balance (in shares) at Dec. 31, 2017   22,584,588    
Net loss (38,387,119)      
Ending balance at Sep. 30, 2018 26,893,028 $ 259 239,181,337 (212,288,568)
Ending balance (in shares) at Sep. 30, 2018   26,059,350    
Beginning balance at Mar. 31, 2018 42,953,284 $ 253 230,297,937 (187,344,906)
Beginning balance (in shares) at Mar. 31, 2018   25,415,798    
Stock-based compensation - restricted stock units ("RSUs") 3,884,725   3,884,725  
Stock-based compensation - employee stock purchase plan ("ESPP") 253,201   253,201  
Stock-based compensation - performance share units ("PSUs") 204,954   204,954  
Issuance of shares for RSUs   $ 1 (1)  
Issuance of shares for RSUs (in shares)   104,112    
Exercise of stock options 2,171   2,171  
Exercise of stock options (in shares)   872    
Cashless exercise of warrants (in shares)   11,370    
Proceeds from contributions to the ESPP 169,879   169,879  
Proceeds from contributions to the ESPP (in shares)   29,458    
Net loss (12,298,371)     (12,298,371)
Ending balance at Jun. 30, 2018 35,169,843 $ 254 234,812,866 (199,643,277)
Ending balance (in shares) at Jun. 30, 2018   25,561,610    
Stock-based compensation - restricted stock units ("RSUs") 3,578,276   3,578,276  
Stock-based compensation - employee stock purchase plan ("ESPP") 67,174   67,174  
Stock-based compensation - performance share units ("PSUs") 207,206   207,206  
Issuance of shares for RSUs   $ 3 (3)  
Issuance of shares for RSUs (in shares)   297,599    
Exercise of stock options 336,237 $ 2 336,235  
Exercise of stock options (in shares)   200,141    
Proceeds from contributions to the ESPP 179,583   179,583  
Net loss (12,645,291)     (12,645,291)
Ending balance at Sep. 30, 2018 26,893,028 $ 259 239,181,337 (212,288,568)
Ending balance (in shares) at Sep. 30, 2018   26,059,350    
Beginning balance at Dec. 31, 2018 18,370,435 $ 265 243,111,741 (224,741,571)
Beginning balance (in shares) at Dec. 31, 2018   26,526,303    
Stock-based compensation - restricted stock units ("RSUs") 3,083,567   3,083,567  
Stock-based compensation - employee stock purchase plan ("ESPP") 87,825   87,825  
Issuance of shares for RSUs   $ 4 (4)  
Issuance of shares for RSUs (in shares)   434,522    
Shares withheld for payroll tax on RSUs (10,207)   (10,207)  
Shares withheld for payroll tax on RSUs (in shares)   (1,329)    
Shares withheld for payroll tax on performance share units ("PSUs") (329,159)   (329,159)  
Shares withheld for payroll tax on performance share units ("PSUs") (in shares)   (44,481)    
Exercise of stock options 400,103 $ 1 400,102  
Exercise of stock options (in shares)   80,201    
Proceeds from contributions to the ESPP 173,167   173,167  
Issuance of shares and warrants in private placements, net of issuance costs 23,319,156 $ 33 23,319,123  
Issuance of shares and warrants in private placements, net of issuance costs (in shares)   3,333,333    
Net loss (11,019,468)     (11,019,468)
Ending balance at Mar. 31, 2019 34,075,419 $ 303 269,836,155 (235,761,039)
Ending balance (in shares) at Mar. 31, 2019   30,328,549    
Beginning balance at Dec. 31, 2018 18,370,435 $ 265 243,111,741 (224,741,571)
Beginning balance (in shares) at Dec. 31, 2018   26,526,303    
Net loss (29,007,691)      
Ending balance at Sep. 30, 2019 21,278,035 $ 309 275,026,988 (253,749,262)
Ending balance (in shares) at Sep. 30, 2019   30,844,921    
Beginning balance at Mar. 31, 2019 34,075,419 $ 303 269,836,155 (235,761,039)
Beginning balance (in shares) at Mar. 31, 2019   30,328,549    
Stock-based compensation - restricted stock units ("RSUs") 2,675,184   2,675,184  
Stock-based compensation - employee stock purchase plan ("ESPP") 122,749   122,749  
Issuance of shares for RSUs   $ 2 (2)  
Issuance of shares for RSUs (in shares)   189,220    
Proceeds from contributions to the ESPP 145,422 $ 1 145,421  
Proceeds from contributions to the ESPP (in shares)   85,765    
Net loss (9,803,996)     (9,803,996)
Ending balance at Jun. 30, 2019 27,214,778 $ 306 272,779,507 (245,565,035)
Ending balance (in shares) at Jun. 30, 2019   30,603,534    
Stock-based compensation - restricted stock units ("RSUs") 2,037,620   2,037,620  
Stock-based compensation - employee stock purchase plan ("ESPP") 62,055   62,055  
Issuance of shares for RSUs   $ 3 (3)  
Issuance of shares for RSUs (in shares)   280,053    
Shares returned (in shares)   (38,666)    
Proceeds from contributions to the ESPP 147,809   147,809  
Net loss (8,184,227)     (8,184,227)
Ending balance at Sep. 30, 2019 $ 21,278,035 $ 309 $ 275,026,988 $ (253,749,262)
Ending balance (in shares) at Sep. 30, 2019   30,844,921