Shares of Raytheon Co., parent of Tucson-based Raytheon Missile Systems, fell more than 4 percent Thursday after reporting that a slowdown in the federal marketplace sapped first-quarter sales.

Raytheon was the last of the top five U.S. government contractors to release quarterly earnings this week, and it had the biggest drop in revenue. Sales declined 6.3 percent to $5.51 billion in the period, with decreases across all four divisions, the company said today.

Raytheon reported higher first-quarter profit after a tax credit and favorable pension adjustments. Net income rose to $596 million, or $1.89 per share, from $488 million, or $1.49 a share, a year earlier. But excluding the tax and pension items, earnings dropped to $1.43 per share from $1.56. Analysts on average had forecast earnings of $1.77 per share on revenues of $5.5 billion, according to Thomson Financial.

Missile Systems reported first quarter net sales of $1.57 billion, down 4 percent from first-quarter 2013, mainly driven by lower sales on U.S. Army programs, the company said. The unit’s operating income fell 3 percent, to $208 million mainly due to the lower sales volume.

During the first quarter, Missile Systems booked $479 million for production and other work on the Standard Missile-3 interceptor for the Missile Defense Agency. The company also booked $164 million for Paveway guided-bomb kits and $86 million for Maverick air-to-ground missiles for foreign customers.

Raytheon’s overall performance highlighted weakness in the defense industry. The Pentagon represents about two-thirds of federal awards, and it is curbing spending as it withdraws combat troops from Afghanistan and absorbs automatic U.S. budget cuts.

“Defense budgets are flattening,” said Brian Ruttenbur, an analyst with CRT Capital Group LLC in Stamford, Conn., which rates Raytheon as fairly valued. “Near-term earnings are going to be totally fine. Longer term, we’re not going to war again. We’re pulling out.”

Raytheon forecast strong bookings and a small improvement in profit margins for the rest of the year but did not change its full-year forecast.

Stock in Raytheon — the fourth-largest federal contractor and the world’s biggest missile maker — closed Thursday at $95.92, down $4.31 in trading on the New York Stock Exchange.

Raytheon had risen 75 percent in trading in the past 12 months, compared with a 19 percent gain in the Standard & Poor’s 500 Index during that time.

The Arizona Daily Star contributed to this report.