(Telecompaper) AT&T has announced the acquisition of advertising technology company AppNexus for an undisclosed sum, confirming recent reports. Privately-held AppNexus operates an independent ad exchange for buying and selling of digital ads, which would help AT&T compete better with Google and Facebook and monetise its new content assets at Time Warner. In a statement, AT&T said AppNexus and its staff including more than 400 software engineers and product managers will become part of advertising and analytics platform, expanding the latter's footprint into Asia-Pacific, Australia, Europe, and Latin America. The deal is expected to close in the third quarter.