According to Compete.com, Bing was able to amass 49.57 million unique visitors in its first month as Microsoft’s official search engine. Bing’s traffic trumps that of Digg (38.96 million) Twitter (23 million), and CNN (28.54 million). We want to stress that this focuses on U.S. visitors, since Compete does not track international visits.
Google in June: 145m
Yahoo in June: 135m
(according to compete.com, so take that as you will)
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Bing More Popular Than Twitter, CNN, and Digg