(written from a Production point of view)
National Amusements was founded in 1936 by Michael Redstone as the Northeast Theatre Corporation and has since gone on to become one of the world's leading media companies with more than 1,500 movie screens and controlling interests in CBS Corporation and Viacom, the current owner of Paramount Pictures.
As the conglomerate is fully owned by "media mogul" Sumner Redstone (son of founder Michael, and until 2016 also the CEO of both Viacom and CBS) and his daughter Shari, this means that the Redstone family is presently the de facto legal majority owner of the entire Star Trek phenomenon, since the acquisition of the franchise in 1994 by the "old" Viacom, Redstone had already acquired previously. The position of individual legal majority ownership of Star Trek had previously been held by the Charles Bluhdorn family (1967-1994), and before that by Lucille Ball (1964-1967; Gene Roddenberry lost all rights and title to his creation the moment he sold his Star Trek is...-pitch to Ball's company, Desilu Studios, in April 1964).
It should be noted that the conglomerate is skirting what is legally allowed. In 1948, the United States Supreme Court had its anti-trust ruling leveled against the motion picture industry – most ironically against Paramount Pictures in particular, being singled out by the Court as proxy for the entire industry – , specifically aimed at the time to break the top-to-bottom vertical hold individual studios hitherto had on the entirety of the industry, otherwise known as the traditional "Hollywood Studio System" (see also Desilu Studios and Universal Studios in this regard). With full control over both production and dissemination of their movie and television productions, the conglomarate as presently organized, is partially negating the intent lawmakers had in mind back in 1948.