What companies today are monopolies?

I would call ATT&T a monopoly ( they were broken up in the 1980 as Pacific Bell and became the "baby Bells" and then morphed into ATT&T. They have bought back many of the "baby Bells" and own wireless companies, internet and TV services. If they aren't a monopoly today they are close to it. Time/Life could be one as well. They own TV networks, AOL, magazines, newspapers, movie studiOS, publishers.