For the second quarter of 2018, overall gross profit margin on a GAAP and non-GAAP basis was 31% and 32%, respectively, compared to 33% on a GAAP and non-GAAP basis in the second quarter of 2017.
Operating expenses for the second quarter of 2018 were $50.2 million, compared to $39.8 million in the second quarter of 2017. Non-GAAP operating expenses for the second quarter of 2018 were $47.1 million, compared to $37.5 million in the second quarter of 2017. Operating expenses for the second quarter of 2018 were impacted by lower research and development credits compared to the second quarter of 2017.
As of June 30, 2018, cash, investments, and restricted cash totaled $144 million. Working capital at the end of the second quarter was $325 million, compared to $332 million at March 31, 2018.
"Our second quarter was highlighted by a number of new AI wins, several installations of supercomputers and storage systems around the world, and expanded storage and AI offerings", stated Peter Ungaro, president and CEO of Cray. "We continue to see signs of improvement in our target market and, although it is still early to predict the extent of the rebound, I remain confident that our market is returning to growth. While we have work left to do, we remain focused on executing on our outlook for the remainder of 2018 and setting the company up for strong long-term growth."
For 2018, while a wide range of results remains possible, Cray expects revenue to be in the range of $450 million. For the third quarter of 2018, revenue is expected to be about $90 million. For 2018, GAAP and non-GAAP gross margins are expected to be in the low-30% range. Non-GAAP operating expenses for 2018 are expected to be in the range of $190 million. For 2018, non-GAAP adjustments are expected to total about $14 million, driven primarily by share-based compensation. For the year, GAAP operating expenses are anticipated to be about $12 million higher than non-GAAP operating expenses, and GAAP gross profit is expected to be about $2 million lower than non-GAAP gross profit.
Based on this outlook, Cray's effective GAAP and non-GAAP tax rates for 2018 are both expected to be in the low-single digit range, on a percentage basis.
While a wide range of results remains possible and it is still early in the planning process, Cray expects 2019 annual revenue to grow modestly compared to its current 2018 outlook.
Actual results for any future periods are subject to large fluctuations given the nature of Cray's business.
Recent highlights include the following: