Here’s a terrific chart in Recode showing all of the big corporate players in media by market cap and industry segment (Top four are AT&T, Verizon, Comcast, and Disney):
A similar article showing several corporate trees was released by Lifecoachcode.com:
A 1951 movie, As Young As You Feel, making fun of conglomerates is terrific. I highly recommend it. A very young Marilyn Monroe makes a cameo in the film.