(Corrects General Atlantic's investment amount, adds context in 8th, 9th paragraphs)
By Gerry Shih
SAN FRANCISCO, July 31 (Reuters) - Private equity firm General Atlantic LLC has invested $100 million in Box, the fast-growing cloud storage start-up seen as a likely candidate for an initial public offering.
The investment - the third funding round by Box in the last 18 months - valued the company at between $1.2 and $1.5 billion, people familiar with the matter said. All told, the latest funding round totaled $125 million, with some of Box's existing backers joining General Atlantic.
Led by 27-year old founder and CEO Aaron Levie, Box competes with Microsoft Corp's SkyDrive and Google Inc's Drive products to provide businesses with a file storage and workplace collaboration service.
The Mountain View, California-based company has expanded aggressively in recent months as it builds out its sales force, particularly across Europe.
General Atlantic's investment follows an $81 million funding round led last October by Salesforce.com and SAP Ventures, the European software giant's investment arm, that valued the company at more than $600 million.
Along with its new stake, the New York-based private equity firm, which manages $17 billion in capital, will also gain a board seat that will be held by Gary Reiner, an operating partner who served as General Electric's chief information officer until 2010.
In recent months Box has sold to CIOs at major companies like Procter and Gamble as well as small businesses.
The infusion of cash will allow Box some flexibility in terms of its IPO timetable, but the company seems to have put those plans on the backburner while it seeks to claim greater market share.
But a public listing remains the most likely outcome, Levie added. The company recently turned down a $700 million cash plus stock acquisition offer by Citrix (CTXS.O> Systems.
"We're in this window in the next couple years when the leaders of this new market is going to be defined," Levie said. "We see a once in a lifetime opportunity. That takes a lot of investment."
Reiner added: "It's a bit of land grab right now, and we're grabbing it." (Reporting By Gerry Shih; Editing by David Cowell and Gerald E. McCormick)