Symantec said Monday that it will spend $350 million to purchase data leak prevention vendor Vontu, making it the latest security vendor to enter this new but crowded market.

The acquisition is expected to close by year's end, putting Symantec in competition with security vendors McAfee, Trend Micro, and Websense, all of whom have acquired data loss prevention companies of their own over the past year.

Vontu sells software that discovers sensitive information on the network and then prevents it from leaking out on laptops or storage devices. With state-mandated data-breach notification laws and new federal regulations making it increasingly important for companies to keep a lid on sensitive data, this kind of technology is becoming attractive to security vendors such as Symantec.

Symantec has already been shipping Vontu's software as an add-on to its Mail Security 8300 series appliances for the past year and a half.

The company's first order of business following the acquisition, however, will be to integrate Vontu's detection software into Symantec's Endpoint Protection 11.0 corporate antivirus software, said Steve Roop, vice president of marketing and products with Vontu.

After that, the software will be integrated with Symantec's archiving and backup products so that IT staff can search the network for sensitive data, he said. When that integration is completed, "rules and decisions about what sensitive data can be backed up and where it can be stored can be put in place," he said. "That's a capability that's never really existed before."

The market for Vontu's products is small but growing, according to company officials.

In 2006, the company booked $29 million in sales, according to Roop. That number is expected to reach $43 million this year, he said.

Founded in 2001, Vontu employs a staff of about 160.