Now I get it (sort of...)

I knew that back in the day Marvel sold off a bunch of movies rights to several studios, but I never completely knew who got what. I found this today and it helps simplify things a bit. Also take into account the various studios got not only the heroes in those titles but also the villains (like Doctor Doom), titles (like Mutant), and associated non-super characters (Franklin "Foggy" Nelson).  and ,as with everything in life,  there are notable exceptions to these rules (like Quicksilver, who is a Mutant and an Avenger).

An online friend just sent me a more updated graphic.