By Philip Elmer-DeWitt
September 27, 2010

Smaller rivals like Jumptap and Millennial Media are also gaining, according to IDC

The pie chart at right is somewhat premature, given that it is IDC’s best guess — via
Bloomberg Businessweek
— of what the $500 million U.S. mobile advertising market will look three months from now.

But it’s an indication of how the winds have shifted. Apple AAPL , which had 0% share of the market before it bought Quattro Wireless in January and launched iAd in June, will end the year at 21%, according to IDC.

Where did that share come from? Chiefly from Google GOOG , Yahoo YHOO , Microsoft MSFT and Nokia NOK , according to the Businessweek piece.

IDC’s before-and-after numbers for the biggest losers below the fold.

Dec. 2009 Dec. 2010
Google 27% 21%
Yahoo 12% 9%
Microsoft 10% 7%
Nokia 5% 2%

. . .
[Follow Philip Elmer-DeWitt on Twitter @philiped]

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