If the rumor mill is accurate, Fox returned its Fantastic Four license to Marvel in exchange for X-Men's TV rights.
Update: Current statements from both Marvel and Fox state that Fantastic Four's film rights still belong to Fox for the time being. That said, Spider-Man went through a similar back-and-forth for months, so who knows? Perhaps this will change in the near future.
Original Story: Marvel Studios has done an incredible job of proving it can make better superhero movies than many companies it once sold film rights to. But this year marked another shift - it proved good enough to get those film rights back. In March, it formed a partnership with Sony bringing Spider-Man to the Marvel Cinematic Universe. Now the rumor mill suggests that Fantastic Four will be next, bringing with it Doctor Doom, Silver Surfer, and even Galactus.
According to the rumor, Fox and Marvel came to an agreement: Marvel would get Fantastic Four's film rights in exchange for X-Men's TV rights. While the information hasn't been confirmed, it does match recent superhero news. Fox just announced it would produce Legion and Hellfire, both based on the X-Men universe. Fantastic Four's associated characters and villains would return to Marvel's wheelhouse if accurate.
While we don't know if this deal is true, it makes an incredible amount of sense for both parties. X-Men is the only Marvel franchise to qualify as a non-Marvel Studios success, so Fox isn't about to give the rights back. Meanwhile, Marvel hasn't had much luck with televised X-Men projects - Wolverine and the X-Men was the last great example, but it didn't have the audience to warrant a second season. Then there's Fantastic Four, which suffered an abysmal film reboot earlier this year that Fox wants to distance itself from. And Marvel is very capable of spinning success stories from superhero franchises few see the appeal in.
Until we learn specifics, what I'm curious about is how the Fantastic Four could possibly join the MCU when it's already filled with super-geniuses. Here's my theory: Marvel's First Family disappeared into a dimensional portal in the 1960s, only to return in present day with superpowers. Ideally that would bypass spending half the film on another origin story, while dropping them into a new world filled with Avengers and aliens. Whatever happens, I find myself eagerly awaiting more news on the nature of this deal.