Consolidated Statements of Cash Flows - USD ($)
$ in Thousands
3 Months Ended
Aug. 31, 2020
Aug. 31, 2019
Cash flows from operating activities:    
Net loss $ (30,832) $ (16,164)
Adjustments to reconcile net loss to net cash used in operating activities:    
Amortization and depreciation 505 531
Amortization of debt issuance costs 4 284
Amortization of discount on convertible notes 1,339 1,030
Inducement interest - warrant exercises and debt conversion 3,345 2,431
Interest expense associated with accretion of convertible notes payable 266
Change in fair value of derivative liabilities (625)
Stock-based compensation 3,692 581
Changes in current assets and liabilities:    
(Increase) in inventories (39,327)
Decrease in prepaid expenses 199 499
Increase (decrease) in accounts payable and accrued expenses 20,127 (4,023)
Net cash used in operating activities (40,948) (15,190)
Cash flows from investing activities:    
Furniture and equipment purchases (59) (5)
Net cash used in investing activities (59) (5)
Cash flows from financing activities:    
Proceeds from private warrant exchange, net of offering costs 7,441 2,256
Proceeds from exercise of warrants 13,469 1,754
Proceeds from warrant tender offers 11,900
Release of funds held in trust for warrant tender offer (854)
Proceeds from exercise of stock options 39
Payment of payroll witholdings related to tender of common stock for income tax withholding (778)
Proceeds from convertible notes payable, net of discount and issuance costs 25,000
Payment of offering costs (1,532)
Dividend declared and paid on Series B preferred shares (243)
Net cash provided by financing activities 44,928 13,524
Net change in cash 3,921 (1,671)
Cash, beginning of period 14,292 3,467
Cash, end of period 18,213 1,796
Supplemental disclosure of cash flow information:    
Cash paid during the period for interest 11 10
Non-cash investing and financing transactions:    
Issuance of stock for note payable redemption and conversions 9,537 1,005
Accrued dividends on Series C convertible preferred stock 207 110
Accrued dividends on Series D convertible preferred stock $ 213