Symantec has bought Veritas for $13.5 billion in an all-stock transaction, as rumoured earlier this week. Symantec shareholders will own around 60 percent of the merged company and the combined company will retain the Symantec name.

The monster deal is just the latest in a glut of big mergers in the IT industry in the past week. Yesterday, Spint and Nextel said they were joining together to make a $70 billion company. On Monday, 3Com paid $430 million for TippingPoint, and Oracle finally got its hands on PeopleSoft for $10.3 billion. And last week, IBM sold off its PC division to Chinese company Lenovo for $1.25 billion.

But back to the Symantec/Veritas deal: Veritas sells backup, archiving and file system software. Symantec sells software to protect home and office computer systems and networks, including firewalls and tools to detect viruses and network intrusions. By joining forces, they will be able to help enterprise customers secure their information better, the companies said. About three-quarters of the combined company's revenue will come from enterprise products and services, they said.

Symantec CEO John Thompson will continue in that role, while his opposite number at Veritas, Gary Bloom, will become vice-chairman and president of the combined company. The new board will be composed of 10 members, six chosen from Symantec's board and four from the Veritas board.

Both boards of directors have approved the deal, which now requires the approval of regulators, and of the shareholders of both companies. Symantec has offered Veritas stockholders 1.1242 Symantec shares for each Veritas share they hold. With Symantec's stock price at $27.38, that values the deal at around $13.5 billion.

This is not Symantec's first acquisition this year - although it is by far the largest. It announced plans to acquire anti-spam software company Brightmail for $370 million in May, and security consultant @Stake in September. Only last week, it announced plans to acquire intrusion system Platform Logic.