* Sees 2014 adj loss of $2.10-$2.30/share vs prev forecast of $2.00-$2.20
* First-quarter revenue $73.9 mln vs est $71.6 million
* CEO links share price fall to end of IPO insider lockups
* To pay $70 mln for nPulse
(Adds CEO and analyst comments; updates shares)
May 6 (Reuters) - Cybersecurity company FireEye Inc forecast a bigger loss this year as it spends more on developing new products, sending its shares down as much as 10 percent in extended trading.
The company uses cloud-based technologies to help businesses fight off sophisticated computer viruses that evade old-school anti-virus software made by companies such as Symantec Corp and Intel Corp's McAfee security division.
Companies and governments are spending more on Internet security in the face of increasingly complex attacks by cyber-criminals, such as the data breach at U.S. retailer Target Corp that resulted in the theft of at least 40 million payment card numbers.
FireEye also said it would acquire privately held nPulse Technologies for about $70 million. NPulse handles ultra-fast search and analysis of network traffic and helps customers detect and prevent data loss.
"We are spending more money on research and development to innovate (and) disrupt the market out there, and ...doing a little bit more in our service area, incident response area and expanding that," David DeWalt told Reuters.
The company said it will announce four new products in the next 90 days, and four new services in the next few months.
FireEye expects full-year adjusted loss of $2.10-$2.30 per share on revenue of $405 million to $415 million. Research and development costs are expected to be as much as 40-43 percent of revenue.
It had previously forecast a loss of $2.00-$2.20 per share on revenue of $400 million to $410 million, with research and development expenses as 36-39 percent of revenue.
Analysts on average were expecting a loss of $2.04 per share on revenue of $406.9 million, according to Thomson Reuters I/B/E/S.
"Given the company's high growth status, investors wanted to see a massive beat and raise out of the gates for 2014, instead the company gave a good, but not great overall performance to start the year," FBR Capital Markets analyst Daniel Ives said.
"The view on FireEye as well as many high growth stocks has shifted from a glass half-full to half-empty view as seen by valuations over the last few months, FireEye has now become a "prove me" stock in the eyes of many tech investors."
FireEye hit the headlines last month when it warned that a sophisticated group of hackers had exploited a bug in Microsoft Corp's Internet Explorer web browser. Microsoft rushed a fix soon after.
But FireEye stock has lost about 40 percent of its value since early April after research firm NSS Labs said FireEye's breach-detection systems underperformed rival offerings by Cisco Systems, Trend Micro Inc and General Dynamics Corp. (http://link.reuters.com/myb29v)
The net loss attributable to FireEye's shareholders widened to $101.2 million, or 76 cents per share, in the first quarter ended March 31, from $26.9 million, or $1.78 per share, a year earlier, before the company listed.
Excluding items, the company reported a loss of 53 cents per share.
Revenue nearly tripled to $73.9 million. Analysts on average had expected a loss of 53 cents per share on revenue of $71.6 million, according to Thomson Reuters I/B/E/S.
Shares fell as low as $33.38 after the bell on Tuesday before recovering to $33.50. They had been as high as $97.35 in March.
DeWalt linked the fall in the shares to the end of share lock-ups after its IPO last September. Some insiders were able to sell shares from March 19 and a further 82.2 million shares will be unlocked for potential sale from May 21.
"This lockup anxiety is related to the number of shares that will come, you know, off lockup coming up this particular quarter," DeWalt said on a conference call with analysts, adding the company's top three executives had no plans to sell shares.
(Additional reporting by Abhirup Roy in Bangalore; Editing by Saumyadeb Chakrabarty and Rodney Joyce)