Google grabbed 72.17 percent of U.S. search market in May, up from 71.4 percent in April for almost a 1 percent gain, according to new stats from HitWise.
Google's gain came at the expense of Yahoo and Microsoft Bing. Yahoo dropped from 14.96 percent in April to 14.43 percent in May, while Bing fell from 9.43 percent the prior month to 9.23 percent.
The numbers stand out against the May search statistics from comScore, which quantified the search market shares using two data sets.
In one set where comScore counted contextual shortcuts and slideshows from Yahoo and Bing, Google's search share at 63.7 percent, Yahoo commanded 18.3 percent and Bing nabbed 12.1 percent.
Subtracting the shortcuts and slideshows, Google grabbed 66.4 percent of the search engine market through May, its greatest share ever. Yahoo's search share for the month was 16.6 percent, with Bing grabbing 10.8 percent.
These stats are forcing financial analysts and other industry insiders to question comScore's metrics. Recognizing this, ComScore is making changes to its methodology for classifying and counting Web searches.
In the meantime, HitWise, which looked at a sample of 10 million Internet users, may be the go-to stat machine for search, particularly for those believing Google's market share is consistently in the 70 percent range.
The researcher also said Google delivered the most searches to the health, automotive, shopping and travel vertical industries.
Yahoo saw gains in the automotive and shopping markets. Bing, which places a heavy emphasis on shopping and commerce saw triple-digit growth in searches for health and shopping.
Google in May revamped its search user interface to include more refinements for users looking to drill down into search results. Google followed that up in June with roll-out of its Caffeine search indexing system.
That means Google has also completed a total overhaul of its search engine in 2010, showing that it is determined not to give up the keys to its search kingdom.