New measurements show that Yahoo continued to improve its share of the U.S. search market after striking a deal last year with Mozilla, the maker of Firefox.
According to comScore, which publishes monthly stats on search share, Yahoo gained 1.2 percentage points in January, climbing to 13%. It was the second straight month of increases for Yahoo.
Yahoo's growth came largely at the expense of Google, which dropped 1 percentage point during January. Google accounted for 64.4% of the U.S. search share last month.
Meanwhile, Microsoft's Bing remained flat at 19.7%.
Since November 2014, when Yahoo partnered with Mozilla to make its search engine the default for U.S. Firefox users, Yahoo's share has grown by 2.8 percentage points, representing a 28% increase.
The continued upward trend in Yahoo's share identified by comScore was similar to the one drawn by Irish analytics firm StatCounter, which earlier in February pointed to a second-consecutive month of gains by the Sunnyvale, Calif. company.
Mozilla changed the default search from Google to Yahoo for U.S. users when it released Firefox 34 on Dec. 1, 2014. The Mozilla-Yahoo deal was a result of the former not renewing its long-standing partnership with Google, which in 2013 generated approximately $275 million in revenue for the open-source developer of Firefox.
But Yahoo's growth, smaller in January than the month before by both comScore's and StatCounter's measurements, may have reached its limit: For the month thus far -- through Feb. 25 -- StatCounter pegged Yahoo's usage share in the U.S. at 10.5%, down from January's 10.9%.