Market research firm ComScore reports Google now has a marketshare of 58.5 percent in the search market, up from 57 percent in September.
The top five providers of Web search all showed at least 5 percent growth in the number of searches in October. Yahoo was number two after Google, followed by Microsoft, InterActiveCorp's Ask.com and Time Warner's network of sites, including AOL.
"They are all growing in the number of search queries but Google is taking a disproportionate share," ComScore spokesman Andrew Lipsman said by phone.
Yahoo sites had 22.9 percent of the U.S. market, a 0.8 percentage-point fall from September. Microsoft slipped to 9.7 percent from 10.3 percent, Ask was flat at 4.7 percent and Time Warner's network dipped 0.1 percentage point to 4.2 percent.
Google shares rose more than 3 percent to a high near $670 before settling back later in regular Nasdaq trade to $666.51, up 2.8 percent. Yahoo shares fell 3.1 percent to $25.87, while Microsoft stock was off half a percentage point at $34.39.