Google Inc., the world's most popular Internet search engine, lost market share last month for the first time since June, according to Nielsen Online.
Google's share of U.S. Web queries fell to 56.3% in December from 57.7% the previous month, Nielsen said. Yahoo Inc. dropped to 17.7% from 17.9%.
The companies lost market share to Microsoft Corp., which upgraded its search engine in September to include shopping, health, map and entertainment options. Microsoft captured 13.8% of searches, up from 12% in November.