SAP says it is offering $45 per share for the Sunnyvale, California-based company. That's a premium of 19.6 percent from Monday's closing price of Ariba shares. Ariba had 100.2 million shares on the market as of March 31, according to FactSet.
Ariba's board has approved the deal and SAP says it should close during the third quarter if Ariba shareholders approve the sale.
SAP, based in Walldorf, Germany, says the deal is worth about $4.3 billion.
Ariba's revenue grew almost 40 percent to $444 million in its latest fiscal year. SAP says the deal should add to its adjusted profit in 2013. The company has around 2,600 employees.