McDonald's filed for U.S. trademark registration last month to protect the brand's name on ground and whole-bean coffee, spurring speculation that the chain may launch a branded coffee for retail sale. Coffee accounted for at least $2.1 billion of the chain's sales last year, and a 2011 study showed stronger loyalty to the brand's brew than Starbucks or Dunkin' Donuts, both of which sell their beans and ground coffee by the pound.