Aug. 29 (Bloomberg) -- Microsoft Corp., the world's biggest software maker, agreed to buyGreenfield Online Inc. and its subsidiary Ciao GmbH for about $486 million in cash to add price- comparison sites in Europe.

Greenfield shareholders will get $17.50 a share, Microsoft said today in a statement distributed by PRNewswire.

Microsoft is looking for ways to catch Google Inc. and boost its Internet business after the failure of its bid for Yahoo! Inc. earlier this year. The Redmond, Washington-based company will need to spend at least $1.2 billion annually to match Google's research and development plus additional funds for marketing, Chief Executive Officer Steve Ballmer said last month.

Microsoft has dropped 22 percent this year amid concern about the Yahoo bid and spending to boost the Internet business. The shares rose 1.4 percent to $27.94 in Nasdaq Stock Market trading yesterday.

Microsoft expects to complete the deal in the fourth quarter.

To contact the reporter on this story: Peter Morley in London on pmorley1@bloomberg.net

Last Updated: August 29, 2008 01:35 EDT