Sun announced revenue of $2.86bn (£1.9bn) for the quarter ending on 30 September, down from $5bn in last year's first quarter.
The company also reported a pro forma net loss of $158m, or 5 cents per share, excluding unusual items. Including investment losses, in-process research and development costs and tax-related charges, Sun showed a net loss of $180m for the quarter.
Earlier this month, Sun predicted that it would report revenue of between $2.7bn and $2.9bn for the quarter. The company slashed its workforce at the same time, saying it would lay off about 3,900 of its employees.
Sun took a heavy revenue hit as result of the 11 September attacks on the US, said company officials.
"Our business nearly ground to a halt in the two weeks following that tragic date," said executive vice-president and chief financial officer, Michael Lehman, in early October. Sun traditionally gets a wealth of its orders during the last month of the quarter, he said.
The company's sales were seriously dented by the impact of the attacks on telecommunications and financial services companies, many of which are Sun customers, he said.