Microsoft's efforts to promote its Bing search engine appear to be paying off—at the expense of partner Yahoo.

Microsoft's share of U.S. search traffic increased to 11.5% in February from 10.7% in January, according to figures released Wednesday by market watcher comScore. Yahoo, currently the number two player in the market, saw its share fall from 17% to 16.8% over the same period.

Market leader Google, meanwhile, enjoyed a miniscule increase of just .1%, from 65.4% in January to 65.5% in February, comScore said.

While month-to-month comparisons show incremental shifts in the market, the longer-term view indicates that Microsoft is gaining significant search share while Google stagnates and Yahoo fades.

Bing launched in June 2009, when Microsoft's share of the search market was just 8.4%, Yahoo's share was 19.6%, and Google held a 65% stake.

ComScore's February numbers thus indicate Microsoft's share of U.S. search traffic has increased 37% since Bing went live, Yahoo's share has declined 14%, and Google has remained flat at the 65% mark.

Microsoft's gains in search are in part due to heavy promotional efforts the company has undertaken to publicize Bing. The latest is a complete makeover its MSN home page that features a significantly more prominent Bing search box and direct integration with Facebook.

Microsoft has also enhanced Bing in recent months with online travel tools, visual search, and a tie-in with the Wolfram Alpha math engine.

Yahoo, for its part, may be suffering from the perception that it's abandoning the search market, as it will eventually outsource search on its pages to Microsoft under an alliance the two companies struck last year.

That will further boost Microsoft's share of the search market.

As for Google, its dominance of the search advertising market is drawing scrutiny from antitrust regulators in the U.S. and Europe, and any efforts by the company to grow its stake significantly beyond the 65% mark could spark regulatory action.

Indeed, many of Google's recent moves to grow revenue come not from attempts to further build search share but from endeavors to exploit new markets like e-mail and cloud-based software such as Google Apps.

The upshot: Microsoft is likely to continue its search gains, at least in the near term, while Yahoo struggles and Google idles.

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