Revenue for the first quarter of 2019 was $72 million, compared to $80 million in the first quarter of 2018. Net loss for the first quarter of 2019 was $29 million, or $0.72 per diluted share, compared to net loss of $25 million, or $0.62 per diluted share in the first quarter of 2018. Non-GAAP net loss was $26 million, or $0.63 per diluted share for the first quarter of 2019, compared to non-GAAP net loss of $21 million, or $0.53 per diluted share in the first quarter of 2018.
Overall gross profit margin on a GAAP and non-GAAP basis for the first quarter of 2019 was 36% and 37%, respectively, compared to 34% on a GAAP and non-GAAP basis in the first quarter of 2018.
Operating expenses for the first quarter of 2019 were $56 million, compared to $52 million in the first quarter of 2018. Non-GAAP operating expenses for the first quarter of 2019 were $53 million, compared to $49 million in the first quarter of 2018. Net Research and Development expenses increased by $6 million in the first quarter of 2019 compared to the first quarter of 2018, driven primarily by the timing of certain milestone reimbursements.
As of March 31, 2019, cash and restricted cash totaled $222 million. Working capital at the end of 2019 was $263 million, compared to $291 million at December 31, 2018.
"We are incredibly honored to have been selected to deliver 'Frontier', an exascale supercomputer to the U.S. Department of Energy's Oak Ridge National Laboratory, which was announced earlier today", stated Peter Ungaro, president and CEO of Cray. "This transformative award serves as further validation for our next-generation Shasta architecture, which will enable groundbreaking research and AI at unprecedented scale. This is a truly historic win for our company, representing the largest contract we've ever received, and with our recent Aurora system at Argonne, the second exascale award for our Shasta platform."
Peter Ungaro added: "We continue to expect 2019 to be a transition year as we do not plan to begin shipping Shasta systems until the end of the year. However, with growing momentum and continued execution, we are well positioned to expand on our market leadership position and deliver strong long-term growth."
For 2019, while a wide range of results remains possible, Cray continues to expect revenue to grow modestly compared to 2018. Revenue is expected to be about $70 million for the second quarter of 2019. For the year, GAAP and non-GAAP gross margins are expected to be in the 30% range. Operating expenses will increase in 2019, primarily driven by investments made toward the exascale award. For 2019, non-GAAP operating expenses are expected be in the range of $215 million for the year, and total non-GAAP adjustments are expected to be about $16 million, driven primarily by share-based compensation. Based on this outlook, the company continues to expect a substantial GAAP and non-GAAP net loss for 2019.
Crays effective GAAP and non-GAAP tax rates for 2019 are both expected to be in the low single-digit range.
Actual results for any future periods are subject to large fluctuations given the nature of Cray's business.
Recent highlights include the following: