Grabbing roles on a deal that could reshape the U.S. media landscape, at least a dozen firms are advising on telecommunications giant AT&T’s proposed $48.5 billion acquisition of DirecTV, the nation’s largest satellite television operator.

Announced Sunday, the deal is the latest in a string of mergers involving mass media and telecommunications companies. It comes three months after cable giant Comcast announced that it had agreed to acquire Time Warner Cable for $45.2 billion.