Network security company FireEye Inc forecast current-quarter revenue below analysts’ average expectation and warned that development costs would rise sharply, sending its shares down nearly 8 percent in after-hours trading. FireEye, which acquired computer forensics specialist Mandiant Corp in January, said it expects revenue of $70-$72 million for the first quarter. Analysts on average were expecting revenue of $76.2 million, according to Thomson Reuters I/B/E/S. FireEye forecast current-quarter research and development costs to range between 50-53 percent of revenue. “Expenses are a little more than expected for the year… I think most investors here would focus on the growth profile, I think that’s kind of splitting hairs in terms of expense shocks,” FBR Capital Markets & Co analyst Daniel Ives said.