December 2014 saw Google experience its biggest drop in search share since 2009, the latest StatCounter report revealed.
Conversely, Yahoo reported its highest search share for over five years, coinciding with Yahoo replacing Google as the default search engine on Firefox 34 browser users in the US, ending Mozilla’s 10-year relationship with Google.
StatCounter CEO Aodhan Cullen said: "The move by Mozilla has had a definite impact on US search. The question now is whether Firefox users switch back to Google."
During the month, Google’s market share hit 75.2%, a fall from 79.3% recorded during the corresponding period last year. The Yahoo search market share, in comparison, rose by 10.4% from 7.4%.
The report added that Firefox users constituted for over 12% of US internet usage during the month.
However, Google’s Chrome and Microsoft’s Internet Explorer maintained their dominance on personal computers, with average US market shares of 37% and 34%, respectively, during last year.
Meanwhile, Apple also revealed plans to replace Google as its default search in iPhone’s Safari by next year, with a rival search platform such as Microsoft’s Bing or Yahoo.