Oracle is to buy rival software company Siebel Systems for $10.66 a share in cash.
Oracle, which said the deal would make it the biggest customer relationship management software maker in the world, valued the takeover at $5.85 billion, or $3.61 billion after subtracting Siebel's $2.24 billion in cash.
The price per share represents a 16.75 per cent premium to Siebel's closing share price of $9.13 on Friday.