UFC Anti-Trust?

It's unclear whether or not this story has any merit. But I'm interested to know what the legal ramifications would be if it were true.

The contention is that UFC, which is kind of like the WWE of ultimate fighting (not in the sense that it's bogus, but in that it's the dominant company and it's run by a single owner), is telling fighters that if they sign deals with a mixed-martial arts videogame, they will be excluded from the UFC for life.

Again, who knows if this is true? But if it was, would the UFC be running afoul of any anti-trust laws, or would they be within their rights?