This list features the top 4 leading search engines based on US Internet usage, ranked by volume of searches for the 4 weeks ending May 31, 2008.

1. www.google.com 68.29%
2. search.yahoo.com 19.95%
3. search.msn.com 4.33%
4. www.ask.com 4.23%

Source - Hitwise - May, 2008 - based on volume of searches.