While Michael Milken’s conference took over the Beverly Hilton, Jeffrey Katzenberg hosted his own, far more private A-list conference for CEOs in Montecito.

One attendee at the Rosewood Miramar told Page Six Hollywood: “There are no plus-ones. It’s the head of every major tech company, and then a handful of celebrities like Oprah, Bieber, Kendrick and the rest are AI billionaires.”

According to a program seen by P6H, Katzenberg’s conference included a special poolside performance by Justin Bieber, a celebrity-judged Lego competition (which was allegedly won by Julia Roberts), YouTube CEO Neal Mohan being interviewed by comedian Nate Bargatze, a chat between “Titanic” director James Cameron and former Disney CEO Bob Iger, chef Nancy Silverton discussing “My Favorite Snacks,” Oprah Winfrey interviewing Chanel CEO Leena Nair, Lego winner Roberts talking to Trevor Noah, NVIDIA CEO Jensen Huang being quizzed by Mellody Hobson, karaoke with Swedish production duo StarGate, Jason Sudeikis chatting with Anduril Industries’ Palmer Luckey and artist Jeff Koons in a panel discussion with LACMA head Michael Govan.

The WNDR26 confab — now in its fifth year — also featured talks by CEO of Palantir Alex Karp, Axel Springer’s Mathias Döpfner, author Brené Brown, Alibaba Group head (and owner of the NBA’s Brooklyn Nets) Joe Tsai, Lego CEO Niels B. Christiansen, FIFA president Gianni Infantino, “Hello” singer Lionel Richie, TBPN hosts John Coogan and Jordi Hays and Duolingo CEO Luis von Ahn, among others.

We also hear that Montecito resident Meghan Markle was among the attendees at the off-the-record confab, where press is barred and no social media is allowed. Producer Brian Grazer was also spotted at the three-day event that was co-hosted by Sujay Jaswa of WndrCo.

“Jeffrey gets a great list… and it’s not for any [clear purpose],” said a source. “Allen & co is for bankers to make deals. This is just for his own ego.”

In recent years, the once-exclusive Allen & Company conference in Sun Valley, Idaho — aka “summer camp for billionaires” — has received Super Bowl-like coverage, while private conferences run by moguls such as Eric Schmidt and Jeff Bezos are increasingly en vogue.