Ariana Grande and Cashmere Cat at Ultra 2015

Ariana Grande and Cashmere Cat at Ultra Music Festival 2015 on March 29.

Seth Browarnik/Startraksphoto

When an estimated 100,000 EDM fans per day flocked to downtown Miami for the 17th annual Ultra Music Festival, held March 27-29, they expected the lights, thumps and fist-pumps of such dance titans as Skrillex, Tiesto and Avicii. Justin Bieber and Ariana Grande? Not so much. But there they were, along with Diddy and Usher, eliciting a surprisingly positive reaction from the crowd, which was flooded with artists and executives angling to get in on the EDM action.

Ultra Crosses Over: 10 Highlights From a Star-Studded Weekend

The festival's clear winner was manager Scooter Braun of SB Projects and School Boy Records, who has a hand in the careers of nearly all of the festival's special guests (Bieber, Grande and Korean star CL, as well as Martin Garrix and ex-Swedish House Mafia member Steve Angello), and orchestrated Garrix and Usher's recent single "Don't Look Down."

Braun, who has been wading into dance music for the past two years (SB talent scout Michael George signed Garrix at Ultra 2013), likened the fest to Woodstock. "I grew up watching footage of Jimi Hendrix, learning about the '70s when shows had this collaborative energy," he tells Billboard. "That's what EDM has."

Diplo, Sean "Diddy" Combs, Skrillex, Justin Bieber at Ultra 2015

Diplo, Sean "Diddy" Combs, Skrillex and Justin Bieber at Ultra Music Festival on March 29, 2015.Seth Browarnik/Startraksphoto

Despite their company's dominance at this year's festival, both SB execs insist the guest spots came together organically: Grande, for example, had a show in Miami that weekend. But the appeal of reaching an audience as sweeping and engaged as Ultra's isn't lost on such executives as Def Jam CEO Steve Bartels, who has Bieber as well as Ultra headliner Axwell & Ingrosso under his roof. He, like Braun, shakes off the idea that the strategy is based on business. Says Bartels, "Artists always want to reach their fans in different, meaningful ways."

This article first appeared in the April 18 issue of Billboard.