Ariel Helwani of MMAFighting.com is reporting that Brock Lesnar is in “serious talks” with UFC about fighting at UFC 200 on July 9, 2016 in Las Vegas, Nevada. Helwani, a credible source in the MMA world, noted talks are progressing well and both sides are close to finalizing a deal.
You can read Helwani’s report at this link.
Brock Lesnar is still under WWE contract, so it’ll be interesting to see how this plays out. WWE has exclusive rights to Lesnar’s services but it’s always been conveyed to us that they would allow for him to take a fight if they could benefit from the promotion. I've also heard they would want to approve the opponent, which according to this report, an opponent isn't close to being finalized at this time.
Helwani’s report doesn’t make any mention of Lesnar's WWE contract, which is good through Wrestlemania 34 in 2018.