Google, Microsoft Added Internet-Search Market Share in December

Google Inc. and Microsoft Corp. took a bigger share of the U.S. search-engine market last month, while Yahoo! Inc. lost ground, according to ComScore Inc.

Google’s share rose to 66.6 percent in December from 66.2 percent in November, while Microsoft grew to 12 percent from 11.8 percent, according to Reston, Virginia-based ComScore. Yahoo! Inc. dropped to 16 percent from 16.4 percent.

Google, which depends on search advertising for most of its revenue, is working to maintain dominance as its biggest rivals team up. Yahoo is farming out its search functions to Microsoft’s Bing, with the two companies splitting revenue. The U.S. search-ad market generated $12.4 billion last year, up 16 percent from 2009, according to EMarketer Inc. in New York.

Microsoft, based in Redmond, Washington, fell 36 cents to $28.19 today on the Nasdaq Stock Market. Google, based in Mountain View, California, dropped 18 cents to $616.69, while Yahoo, based in Sunnyvale, California, rose 10 cents to $16.75.

To contact the reporter on this story: Brian Womack in San Francisco at bwomack1@bloomberg.net

To contact the editor responsible for this story: Tom Giles at tgiles5@bloomberg.net