Google, Microsoft, and Yahoo! have swiftly lost share in the U.S. mobile advertising market to Apple's new iAd, reports "Bloomberg Businessweek" (http://www.businessweek.com/technology/content/sep2010/tc20100926_023792...).

Apple will end the year with 21% of the market, according to estimates provided to Businessweek.com by researcher IDC. Google's share will drop to 21% from 27% last year, when combined with results from AdMob, the ad network it bought in May. Microsoft will drop to 7% from 10%.

"Apple's acquisition of Quattro and Steve Jobs's launch of iAd put a spotlight on mobile advertising," Paran Johar, chief marketing officer at rival mobile ad network Jumptap, told "Bloomberg."

Apple's push into mobile ads may be a reason for its rivals' market-share declines, the article adds. Since June, the number of brands that have agreed to run ads through Apple's iAd network has doubled, according to Natalie Kerris, a spokeswoman for Apple.

On June 7, Apple said it had US$60 million in iAd commitments from marketers, including food and personal-care product maker Unilever, electronics retailer Best Buy, and satellite-television service provider DirecTV.

Ads combine the emotion of TV advertising with the interactivity of Internet advertising, according to Apple CEO Steve Jobs. Apple has iAd commitments for 2010 totaling over US$60 million, which represents almost 50 percent of the total forecasted US mobile ad spending for the second half of 2010, says Jobs.

He adds that iAd, which is built into iOS 4, allows users to stay within their app while engaging with the ad, even while watching a video, playing a game or using in-ad purchase to download an app or buy iTunes content.

Developers who join the iAd Network can incorporate a variety of advertising formats into their apps. Apple will sell and serve the ads, and developers will receive 60% of the iAd Network revenue, which is paid via iTunes Connect. iAds require iOS 4.