Annual report [Section 13 and 15(d), not S-K Item 405]

Convertible Instruments and Accrued Interest - Preferred stock (Details)

v3.25.2
Convertible Instruments and Accrued Interest - Preferred stock (Details)
$ / shares in Units, $ in Thousands
 12 Months Ended
May 31, 2025
USD ($)
$ / shares
shares
May 31, 2024
USD ($)
$ / shares
shares
Class of Stock    
Accrued dividends | $ $ 8,269 $ 6,791
Accumulated deficit | $ $ (887,786) $ (891,531)
Preferred stock, par value | $ / shares $ 0.001 $ 0.001
Series B Convertible Preferred Stock    
Class of Stock    
Shares of preferred stock outstanding 19,000 19,000
Common stock conversion rate 10 10
Total shares of common stock if converted 190,000 190,000
Undeclared dividends | $ $ 24 $ 19
Total shares of common stock if dividends converted 48,000 38,000
Undeclared dividend, shares 10  
Preferred stock dividend, value per share | $ / shares $ 0.25  
Preferred stock conversion price, per share | $ / shares 0.5  
Preferred stock, liquidation preference per share ($ per share) | $ / shares 5  
Preferred stock, par value | $ / shares $ 0.001 $ 0.001
Series C Convertible Preferred Stock    
Class of Stock    
Shares of preferred stock outstanding 6,000 6,000
Common stock conversion rate 2,000 2,000
Total shares of common stock if converted 12,670,000 12,670,000
Accrued dividends | $ $ 3,769 $ 3,135
Total shares of common stock if dividends converted 7,538,000 6,270,000
Preferred stock conversion price, per share | $ / shares $ 0.5  
Preferred stock, liquidation preference per share ($ per share) | $ / shares $ 1,000  
Preferred stock dividend rate, as a percent 10.00%  
Preferred stock, par value | $ / shares $ 0.001 $ 0.001
Fractional shares 0  
Series D Convertible Preferred Stock    
Class of Stock    
Shares of preferred stock outstanding 9,000 9,000
Common stock conversion rate 1,250 1,250
Total shares of common stock if converted 10,565,000 10,565,000
Accrued dividends | $ $ 4,500 $ 3,656
Total shares of common stock if dividends converted 9,000,000 7,312,000
Preferred stock conversion price, per share | $ / shares $ 0.8  
Preferred stock, liquidation preference per share ($ per share) | $ / shares $ 1,000  
Preferred stock dividend rate, as a percent 10.00%  
Preferred stock, par value | $ / shares $ 0.001 $ 0.001
Fractional shares 0