US telco AT&T has made a bid for internet company Yahoo, according to sources who spoke to Bloomberg, with operators increasingly targeting mobile advertising.

If true this bid puts AT&T up against its main US competitor Verizon, which has long been the favourite to acquire Yahoo. Verizon made a major strategic move into online content and advertising when it acquired AOL a year ago, so has always seemed a natural fit for Yahoo, which has struggled for strategic direction.

Yahoo invited bid for the business earlier this year and reportedly received more than ten in the first round. The company has been working on narrowing down that list since then and is expected to reveal the results of that process soon.

AT&T bought into media itself last year with the $49 billion acquisition of satellite TV company DirecTV. One of the parts of Yahoo that could be especially appealing to AT&T is its advertising technology, which could help it monetise some of this video content.

There are probably also strategic reasons for AT&T to make it as difficult and expensive as possible for Verizon, should the latter eventually succeed in acquiring Yahoo. There is currently a content land-grab among large telco groups, who are hoping to counter the commoditization of their core offerings by bundling premium content and establishing mobile advertising as a significant revenue stream.