San Francisco -- Thoma Bravo, the large private equity firm with offices in San Francisco and Chicago, said on Tuesday it will sell San Jose-based portfolio company SonicWall, a provider of IT security and data backup tools, to computer giant Dell. Financial terms of the deal, expected to close within 45 days, were not disclosed. Thoma Bravo originally led a group that took the company private in a deal that closed in 2010. "During our ownership of the company, their implementation of our operational strategies resulted in a significant increase in SonicWall's value," said Orlando Bravo, managing partner of Thoma Bravo. Founded in 1991, SonicWall currently has offices in 23 countries and more than 950 employees.