WALTHAM, Mass. — Raytheon Co. said Thursday that third-quarter profit fell, but the defense contractor raised its forecast for full-year revenue and earnings.

Third-quarter sales fell at three of Raytheon's four operating units, including Tucson-based Raytheon Missile Systems, and were essentially flat at the other.

The company's shares fell $1.18, or 1.5 percent, to $77.31 in morning trading. They began the day up 36 percent for the year.

Net income fell 2 percent to $489 million from $500 million in the 2012 third quarter, and included $2 million in profit from discontinued operations. In both quarters, the profit amounted to $1.51 per share, due to a reduction in the number of outstanding shares since last year.

Analysts expected $1.32 per share, on average, according to FactSet.

Revenue dropped more than 3 percent to $5.84 billion, slightly above analysts' forecast of $5.82 billion. Sales fell in all of its business units, with the steepest drop, 7 percent, in its space and airborne systems division. Sales fell 3 percent in both the missiles and information-services units and were nearly flat in defense systems.

Raytheon Missile Systems, Southern Arizona's biggest private employer, posted third-quarter net sales of $1.64 billion, down 3 percent from the same period last year, mainly due to lower sales on U.S. Army sensor programs. The company had $202 million of operating income, down 5 percent from third-quarter 2012 primarily due to a change in contract mix, the company said.

Raytheon raised its forecast of full-year profit from continuing operations to between $5.67 and $5.77 per share, up from its July outlook for between $5.51 and $5.61 per share. And it raised its 2013 revenue projection by $100 million, to between $23.6 billion and $23.8 billion. It said the forecasts included the effects of the recent partial government shutdown.

Analysts were expecting 2013 profit of $5.65 per share on revenue of $23.7 billion.

The company said it had bookings of $5.7 billion in the quarter, which it ended with a backlog of $32.2 billion in work, down from $35.0 billion last year.

Chairman and CEO William Swanson said the "overall economic environment has been challenging" but the latest results showed the company's focus on technology that customers want.