Mumbai: Microsoft Corp. has acquired privately held AdECN, an online hub for buying and selling internet ad space, marking its latest push into a sector led by rivals Google Inc. and Yahoo Inc.

Santa Barbara, California-based AdECN, which launched its service in October 2005, works like a stock market for advertisers and publishers to buy and sell advertising, Kevin Johnson, president of Microsoft`s platforms and services division, said at an analyst meeting.

AdECN conducts real-time auctions for internet ad space that are triggered when an individual surfs onto a page owned by an AdECN member. The system instantaneously culls demographic data about the individual, which is factored into bidding that is carried out based on members'' predefined criteria.

All it takes to begin and end the auction and display the ad is just 12 milliseconds, says AdECN.

Customers buy "seats" on the exchange, the same way seats are bought on the New York Stock Exchange. The cost of the seats vary according to a member`s projected volume and the quality of its traffic, according to AdECN`s Website.

Participating agencies in AdECN''s ad exchange include AMS Global Online, A Simple Internet, and Sierra Group Marketing. Financial terms of the transaction were not disclosed.

The deal is the latest step in Microsoft''s campaign to become a major player in the digital advertising market.

Microsoft had also announced deals under which it will serve up ads to visitors on the Web 2.0 news site Digg and place electronic ads in sports video games published by Electronic Arts.

In May, it acquired Screen Tonic SA that makes software designed to connect online advertisers with users of mobile phones and other digital devices. Earlier this month, Microsoft also tied up with Ask.com for a paid search programme.

Microsoft is also currently developing a web analytics product code named Gatineau.