Media mogul Sumner Redstone puts the business in show business through National Amusements. What began as a humble drive-in theater operation evolved into a powerhouse that controls just under 80% of media giants Viacom and CBS Corporation . Redstone, the controlling stockholder of National Amusements, is former chairman of Viacom and CBS Corporation. True to its roots, National Amusements also operates Showcase Cinemas, Multiplex Cinemas, and Cinema de Lux branded theaters -- about 950 screens total -- in the US, the UK, and Latin America. National Amusements additionally operates IMAX theaters in the US and Argentina, and is a partner in online ticketing service MovieTickets.com .