Justin Bieber, Ariana Grande Still With Scooter Braun

Music executive Scooter Braun still has A-list clients like Justin Bieber and Ariana Grande under his belt, despite reports ... but we're told he's got his hands full -- because he's stepping into a larger role.

Sources familiar with what's happening behind the scenes tell TMZ ... all of Scooter's clients, including Justin and Ariana, are still under contract with his company, SB Projects.

However, we're told contract negotiations have been going on for several months as he shifts into his bigger role as CEO of HYBE America -- his multi-billion-dollar South Korean entertainment company that manages the likes of BTS.

Sources say folks spreading rumors about Bieber and Ariana are off ... Scooter's team at SB Projects is still handling both Justin and Ariana as they work through figuring out what the new structure will look like.

For those unaware, reports have been flying recently about the 2 superstars leaving SB, but it's been a bit of a gray area until now.

There was also word that Demi Lovato has stepped away from Scooter -- our sources confirm her departure, saying it was a mutual decision.