| In millions, except per share items | Dec-30-18 | Dec-31-17 | Jan-01-17 | Dec-27-15 | Dec-28-14 |
| | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | 3.1 | 34.4 | -1.9 | -7.0 | -13.6 |
| Depreciation and amortization | 4.9 | 2.7 | 1.3 | 1.0 | 0.9 |
| Stock-based compensation | 17.3 | 10.7 | 3.1 | 1.2 | 0.6 |
| Change in working capital [+] | -1.8 | -6.0 | -0.5 | -5.4 | -7.0 |
| Accounts receivable | -1.5 | -12.3 | 1.2 | -5.9 | -2.1 |
| Inventories | -7.6 | 3.2 | -8.4 | 3.4 | -4.0 |
| Other current assets | -2.6 | -0.3 | -0.9 | 0.5 | |
| Accounts payable | 5.8 | -5.8 | 1.8 | -4.4 | 3.4 |
| Accrued expenses | 4.0 | 9.3 | 5.8 | 0.9 | |
| Other | | | | | -4.2 |
| Other operating activities | 1.4 | -35.2 | 0.4 | -1.8 | 0.0 |
| Cash from operations | 24.8 | 6.6 | 2.3 | -12.1 | -19.1 |
| |
| Capital expenditures | -5.1 | -9.0 | -2.7 | -1.8 | -1.3 |
| Purchases of property and equipment | -5.1 | -9.0 | -2.7 | -1.8 | -1.3 |
| Purchases of intangible assets | -1.7 | | | | |
| Purchases of short-term investments, net | -3.5 | -94.7 | | | |
| Purchases of short-term investments | -69.7 | -131.8 | | | |
| Sales of short-term investments | 66.2 | 37.1 | | | |
| Other cash from investing | -0.6 | | -0.1 | 0.1 | |
| Cash from investing | -11.0 | -103.6 | -2.8 | -1.7 | -1.3 |
| |
| Issuance of common stock, net | 8.4 | 7.7 | 98.7 | 0.2 | 0.1 |
| Other cash from financing | -7.5 | -3.4 | 0.0 | 14.1 | 20.4 |
| Cash from financing | 0.9 | 4.3 | 98.7 | 14.3 | 20.6 |
| |
| Free cash flow | 19.7 | -2.3 | -0.4 | -13.8 | -20.3 |
| Per share (diluted) | $0.50 | ($0.06) | ($0.06) | ($17.99) | ($31.00) |
| |
| Cash paid for interest | | 0.2 | 0.5 | 0.4 | |