IBM has agreed to acquire major human-resources software player Kenexa for about $1.3 billion, the company announced today.

Kenexa offers talent management, recruiting, and retention software to nearly 9,000 customers in 21 countries. It has 2,800 employees, and it will help IBM with its “social business” credentials.

IBM will pay $46 per share for Kenexa, a 42.5 percent premium on top of Kenexa’s closing price Friday on the NASDAQ exchange.

The deal helps IBM be more competitive with SAP, which bought SuccessFactors for $3.4 billion, and Oracle, which purchased Taleo for $1.9 billion.

“Every company, across every business operation, is looking to tap into the power of social networking to transform the way they work, collaborate, and out-innovate their competitors,” said IBM general manager for social business Alistair RennieĀ in a statement. “IBM is uniquely positioned to help clients generate real returns from their social business investments, while helping them gain intelligence into the data being generated in these networks to be more competitive in their markets.”

IBM expects the deal to close in the fourth quarter of this year.

IBM photo via Daniel Voyager/Flickr