v3.19.3.a.u2
Consolidated Statements of Cash Flows - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Operating activities      
Net loss $ (290,976) $ (230,699) $ (119,491)
Adjustments to reconcile net loss to net cash used in operating activities:      
Stock-based compensation expense 51,696 33,817 23,100
Depreciation and amortization expense 7,070 3,732 956
(Accretion) amortization of investment (discounts) premiums (1,330) (1,885) 732
Loss on disposals of property and equipment 1,027 0 0
Non-cash operating lease expense 964 0 0
Non-cash interest expense 0 211 0
Asset retirement obligation accretion expense 71 49 0
Changes in operating assets and liabilities:      
Prepaid expenses and other current assets (998) (5,764) (784)
Operating lease assets 239 0 0
Other assets 322 (314) 2
Accounts payable 4,213 (1,958) 2,163
Accrued compensation 4,070 4,972 1,919
Accrued research and development expenses (10,869) 15,204 1,598
Other current liabilities (394) 2,491 1,896
Operating lease liabilities (731) 0 0
Other long-term liabilities 0 372 407
Net cash used in operating activities (235,626) (179,772) (87,502)
Investing activities      
Purchases of short-term investments (270,230) (466,489) (176,459)
Proceeds from maturities and sales of short-term investments 336,261 306,125 296,600
Purchases of property and equipment (5,733) (35,925) (20,232)
Proceeds from sale of property and equipment 161 0 0
Net cash provided by (used in) investing activities 60,459 (196,289) 99,909
Financing activities      
Proceeds from sale of common stock in underwritten offerings, net 140,888 293,290 0
Proceeds from issuance of common stock through ATM facilities, net 47,729 47,586 19,156
Proceeds from employee stock awards 7,350 24,691 1,249
Taxes paid related to net share settlement of restricted stock units (6,695) (7,503) (357)
Principal payments on finance and capital lease obligations (486) (528) 0
Net cash provided by financing activities 188,786 357,536 20,048
Increase (decrease) in cash, cash equivalents and restricted cash 13,619 (18,525) 32,455
Cash, cash equivalents and restricted cash at beginning of period 62,092 80,617 48,162
Cash, cash equivalents and restricted cash at end of period 75,711 62,092 80,617
Non-cash investing and financing activities      
Proceeds from issuance of common stock through ATM facilities received subsequent to December 31, 2019 1,185 0 0
Property and equipment purchases included in accounts payable and other accrued liabilities 276 1,579 10,122
Accrued costs related to underwritten public offering 172 0 160
Capitalized lease obligations 0 441 9,904
Property and equipment acquired under capital leases 0 191 1,076
Asset retirement costs 0 88 580
Interest capitalized during construction period for build-to-suit lease arrangement 0 77 264
Proceeds from options exercised received subsequent to December 31, 2017 0 0 439
Supplemental cash flow disclosure      
Cash paid for interest 50 240 0
Cash paid for taxes $ 0 $ 0 $ 0

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