Opera Software announced today that it has acquired demand-side mobile advertising platforms Mobile Theory Inc. and 4th Screen Advertising Ltd. Further details of the transactions were not disclosed.

Opera said the acquisitions “significantly expand” the services and opportunities it can offer to advertisers and publishers across all mobile platforms, both feature phones and smartphones, on platforms including iOS, Android, Blackberry, Java and Symbian.

The benefits flow the other direction too, since the deals improve Opera’s ability to monetize traffic through its Opera Mini and Opera Mobile browsers. Collectively, Opera has more than 160 million monthly active users that generate more than 100 billion page views and consume more than 16 Petabytes of mobile data services a month, as of December 2011.

Two years ago, Opera acquired supply-side mobile advertising platform AdMarvel. Lars Boilesen, Opera Software CEO, said in 2011 Opera helped generate over $200 million for its publishers.

Based in London, 4th Screen Advertising is a premium mobile advertising network focused on serving European markets. It offers brands and advertisers engagement and rich media-based mobile campaigns, and its clients include The Guardian, MTV, Global Radio, Shazam and IMDb.

Mobile advertising network Mobile Theory serves the U.S. mobile advertising market from its headquarters in San Francisco and its offices in New York City, Chicago, Los Angeles and Seattle. Reaching more than 60 million mobile users on over 300 mobile sites and apps, Mobile Theory serves up 2 billion impressions per month.

“This is yet another important step in Opera’s quest to create even more economic value in the mobile ecosystem,” Boilesen said. “Today, we are announcing the acquisition of two great demand-side platforms for mobile advertising. With these assets, and our very popular mobile browsers, Opera is uniquely positioned to deliver end-to-end mobile advertising solutions to brands, agencies, publishers and mobile operators across the globe. We are delighted to welcome the Mobile Theory and 4th Screen team to the Opera family.”

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