• by Mark Walsh  @markfwal, February 16, 2012

Pushing further into mobile advertising, Opera Software is acquiring a pair of mobile ad networks: U.S.-based Mobile Theory and 4th Screen Advertising in the U.K. for $10 million total. The deals follow two years after Opera, best known for its Web browsers, bought mobile ad network AdMarvel.

While AdMarvel caters mainly to publishers and developers, Opera CEO Lars Boilesen said the acquisitions of two mobile demand-side platforms would be complementary. “Opera is uniquely positioned to deliver end-to-end mobile advertising solutions to brands, agencies, publishers and mobile operators across the globe,” he stated.

The addition of both ad networks could help Opera to monetize its own app inventory. The Norway-based company last year launched its own mobile app storefront to compete with Apple’s App Store and the Android Market. It features free and paid apps for virtually every type of device and mobile platform, including the iPhone, BlackBerry and Android.

By picking up Mobile Theory, Opera also expands its footprint in the U.S. mobile market, where the ad network reaches more than 60 million users on 300 mobile sites and apps. Across those platforms, it serves 2 billion impressions a month. Advertisers on the network include Microsoft, Chevrolet, AstraZeneca, Coca-Cola and Capital One.

The company last summer teamed with contextual advertising firm NetSeer to launch a new ad unit using semantic technology for targeting. Last Otober, it introduced its “Overpass” ad unit that run on standard Web pages in a mobile browser. The format is geared to sites that don’t yet have a mobile-optimized presence.

Opera is among several Europe-based software and mobile companies that have focused on expanding in North America in the last two years. Others include mobile ad network inMobi and mobile marketing firm Velti. Gartner has projected mobile ad revenue in the region will increase to $5.79 billion in 2015 from about $702 million in 2011.

4th Screen, which focuses on the European market, works with publishers including The Guardian, Shazam, MTV and IMDb. The company says it delivers 500 million impressions a month for advertisers such as Disney, Warner Bros, Nokia and Barclaycard.