Symantec

(SYMC) - Get Report

, the leading anti-virus software maker, will buy privately held anti-spam vendor Brightmail for $370 million in cash, the companies announced after the closing bell Wednesday.

Brightmail, which filed to go public in March, has grown rapidly. In 2003, it lost $4.97 million, or 87 cents a share, on sales of $12.18 million. By 2004, the company had turned a profit, earning $1.17 million, or 20 cents a share, on sales of $26.04 million, according to documents filed with the

Securities and Exchange Commission

. At the end of January, the company had $26 million in cash and short-term investments on hand.

The acquisition is expected to close by early July if regulators approve.

"Spam has increasingly become one of the most severe threats to individuals and enterprises today, topping viruses as the number one problem plaguing email systems and administrators," John W. Thompson, Symantec chairman and chief executive officer said in a statement.

"Brightmail is the leader in helping enterprises, service providers, and wireless carriers mitigate this threat. Their patented technology is a critical component of a comprehensive gateway security solution," he said.

Thomson did not indicate how the acquisition will affect Symantec's financials, saying the company will discuss that "at some point in the future."

Symantec made a strategic investment in Brightmail in July 2000 and currently holds an approximately 11% equity stake in the company.

Brightmail CEO Enrique Salem denied that the recent slump in tech stocks prompted Brightmail's decision not to go ahead with its public offering. "That had nothing to do with it," he said in an interview.

Brightmail, like other software companies, sees a significant opportunity overseas, and Symantec, which earns more than half its revenue offshore, is well positioned to help Brightmail expand. "What we are saying is that the email security market is very large and our combined companies can capitalize on it," Salem added.

Symantec shares were recently down 48 cents, or 1%, to $46.60 in after-hours trading; the stock closed Wednesday's regular session up 45 cents, or 1%, to $47.08.