Private equity firm Apax Partners has agreed to acquire majority interest in Sophos, in a transaction valuing the IT security and data protection firm at $830m.

Up on completion of the transaction, founders of Sophos will retain a significant minority shareholding. TA Associates, a minority shareholder in Sophos since 2002, will sell its full interest to Apax in the transaction.

Based in Abingdon, England, Sophos endpoint security and data protection product offers anti-virus, anti-spyware, client firewall, host intrusion prevention, network access control, application control, device control, disk encryption and data leak prevention.

Sophos has over 100 million users in more than 150 countries, with customers including Cisco, Marks and Spencer, Heinz and Harvard University. The company generated revenue in excess of $260m in the fiscal year ended March 31, 2010.

Steve Munford, CEO at Sophos, said: “Over the past three years, Sophos has prospered operationally and financially, growing our revenues at a 27% cumulative annual growth rate and generating strong cash flow. As the market continues its migration from point solution to tailored, unified security suites, Sophos strategy to offer the worlds most resilient, cost effective solutions without any additional complexity remains key.

“Apax financial backing, combined with Sophos deep understanding of security and data protection is great news for our customers, prospects, partners. It is also a testament to the efforts of all those who helped bring Sophos to where it is today.”