"At over 19 million active accounts globally, Roku has built one of the biggest, most advanced content distribution platforms of any U.S. company," Roku Chief Executive Anthony Wood and Chief Financial Officer Steve Louden said in a shareholder letter. If Roku were a traditional pay-TV provider, it would rank No. 3 in the U.S. after Comcast ( CMCSA ) and AT&T ( T ), they said.