To get a little more in depth, Sony has had the rights to Spider-Man since the mid-1990's when Marvel started selling rights. These rights were generally in perpetuity as long as movies were being made every so often. This is why the X-Men & Fantastic Four were at Fox , Hulk was at Universal, etc. This is why Marvel Studios started with Iron Man - it was a character that wasn't sold (Avengers was not that popular in the 90's). This was pre-Disney. Anyway, Disney buys Marvel (who had a distribution deal with Paramount but it was only that and Marvel owned these films outright). Marvel worked with Universal on Hulk, but after the Disney buyout that became less likely. After "The Amazing Spider-Man" movies fizzled Sony decided to do a similar deal, ceding creative control to Marvel Studios but still distributing the films. Venom, an offshoot of Spider-Man is 100% controlled by Sony still. Now that Disney has purchased Fox, they have 100% control of X-Men and Fantastic Four, and fans expect that they will be brought in to the overall Marvel Cinematic Universe.