Symantec announced today that it has agreed to acquire privately held Clearwell Systems for $390 million, bolstering the security company's efforts in the growing market for electronic legal-document discovery.

Symantec, best known for its Norton security products for PCs, will combine Clearwell's analysis and archiving of legal documents with its own Enterprise Vault e-discovery software. The e-discovery software market is expected to grow at an annual rate of 14 percent and is estimated to reach $1.7 billion by 2014, according to Gartner industry research.

"As information continues to grow at unprecedented rates, the biggest challenge for customers is to protect, manage, and back up this information as well as have the ability to categorize and discover it efficiently," Deepak Mohan, senior vice president of Symantec's Information Management Group, said in a statement.

Symantec said the purchase would dilute adjusted earnings by 1.5 cents per share in fiscal 2012 and is expected to add to fiscal 2013 earnings. The deal is expected to close by the end of September.

Symantec shares fell 11 cents to close at $19.57.