The Hulk was thrust into the Marvel Cinematic Universe back in 2008 when Tony Stark made a cameo appearance at the end of The Incredible Hulk. By that time we were slowly learning that Marvel was building up to The Avengers. However, since the film’s release we have yet to hear news on a solo Hulk film. We’ve heard many rumors throughout the since the release of The Avengers, one of the biggest ones being that the “Planet Hulk” storyline would be the premise of the film. And now we are finally learning why we haven’t seen a solo Hulk film despite the success of the MCU and fan requests.

Simply enough, the film rights are still over at Universal. This perhaps may explain a few things like why Betty Ross’s name is never mentioned in the first and (minor spoiler) second Avengers. Hit the jump for more.

Mark Ruffalo revealed the reason to Collider over the weekend during the Avengers: Age of Ultron press day:

While the actor did mention that he only had four films left on that contract, he also said that number could change given how he may appear in any number of the character films as well as Avengers: Infinity War. He will, however, not appear in Guardians of the Galaxy 2. Director James Gunn also shot down the idea calling it “100% BS.”

With the film rights still over at Universal, it is hard to tell when exactly we will be able to get a solo Hulk film. Ruffalo has said in the past that as much as he would like to get his own film, he isn’t in any rush to get one released. Age of Ultron director Joss Whedon has said that a Planet Hulk movie would be extremely difficult.

But at least we have a definitive answer as to why we aren’t able to get one at the moment.

Avengers: Age of Ultron opens in theaters on May 1, 2015.

[Source: Collider]