He will be replaced by Enrique Salem, the company's chief operating officer, effective April 4, 2009, Symantec said in a statement released Monday afternoon. During his tenure, Thompson built Symantec from a consumer desktop software vendor, best known for its Norton products, into a leading enterprise software provider. The company aggressively acquired new software companies including its most high-profile purchase: the 2005 US$10.5 billion acquisition of enterprise storage software vendor Veritas.

"He grew it from what was essentially a desktop software vendor to arguably the most important security pure-play," said Andrew Jaquith, a senior analyst with Forrester Research who formerly worked for Symantec under Thompson's leadership. "He's made a lot of gutsy calls; buying Veritas was an amazingly gutsy call, and it was the right one."

Investors might disagree with that assessment. Symantec's stock [SYMC] dropped on news of the Veritas merger four years ago and has never returned to its pre-acquisition highs.

Although Symantec has warned of a slowdown in sales recently, executives said Monday that they have been working on the transition for the past 10 months already, an effort called "Project Texas."

"I've always believed that 10 years was long enough to sit in this role," Thompson said in a call with financial analysts Monday.

Come April, Thompson will remain as chairman of Symantec's board of directors, but in an interview following the call he said his immediate retirement plans involve spending "a lot more time" in Hawaii.

A supporter of President-elect Barack Obama, Thompson has been considered a possible appointee to the incoming Obama administration. Thompson said he has had no conversations with the Obama camp and has no plans to work in Washington.

But he didn't entirely rule out the possibility. "Clearly if I were to get a call from the president-elect, it would be not only stupid, but unpatriotic to not take the call and consider anything that he might want to chat with me about," he said.

Salem, 43, had been groomed for the post since Symantec acquired his antispam company, Brightmail, in 2004. He headed Symantec's consumer business and then the worldwide salesforce before being promoted to COO in January of this year.

Years before Brightmail, Salem began his career at Symantec as a 25-year-old software engineer working on Norton Utilities for Windows.

Thompson said Salem would bring new energy to the role of CEO. "Enrique's got infinitely more energy than I have," he said. "This is the perfect time for us to put someone who is as energetic and intelligent in the job to run this company."