With reports that Red Bull GmbH is looking to sell the New York Red Bulls, and the backlash over the firing of coach Mike Petke, fans have rented billboards and ranted for ownership to sell. But the sale is probably not happening anytime soon according to local investment banker Jason Ader, who tried to buy the team a few months ago.

In the wake of Red Bull Head of Global Football Gerard Houllier’s comments to The Post that the team planned to cut costs and Sports Illustrated’s story that owner Dietrich Mateschitz was ready to cut bait, fans have revolted over Petke’s firing by renting a billboard in protest and getting #redbullout to trend on Twitter.

But Ader — the CEO of Ader Investment Management and the director of the Las Vegas Sands Corporation, part of a $350 million group aiming for an MLS expansion side in Las Vegas — doesn’t think Red Bull is selling. And he should know; the investment banker who actually has Red Bulls season tickets tried to buy the club he supports, only to be told it wasn’t for sale.

“I’ve done a tremendous amount of research,’’ said Ader, who approached Oliver Mintzlaff, Red Bull’s Head of Global Football-Commercial, last year about buying the team. “I expressed my interest to Oliver, who very quickly told me that the team is not for sale. I told him I’d be happy to help the team’s success, with youth development, fan engagement, whatever.

“It was in 2014 right around the time [I got involved in the Las Vegas bid]. I expressed interest, if the team was interested or Red Bull was interested in selling. He said they weren’t. … Obviously that’s the case today. I don’t think [it’s changed]. It was just a few months ago that I shared my interest.’’

Ader — who actually made the final contribution to fund the billboard on Route 280 near Red Bull Arena — also pointed toward Red Bull having just hired a new sporting director (Ali Curtis) and manager (Jesse Marsch) as signs that they may be streamlining but not selling.

“You wouldn’t change your sporting director and manager if you were planning on selling the team immediately. I think Oliver is trying to improve profitability, stems losses, get in a better financial position,’’ Ader said. “I’d hope they give me a chance to bid. I’d have interest, but right now, I sense they just want to improve the financial position of the club.’’

For Ader, his attempt to buy the team was not just about profit but was a personal matter. Ader remembers Petke making a birthday video for his son, Jack, and said his daughter Sophia’s favorite sporting memories are of going to her first Red Bull game and being enamored by the passion of the supporters.

“My family had never been to soccer game,’’ Ader said. “I took my daughter to see the Red Bulls in 2012. She’d been to the Knicks, Mets, Yankees — she hadn’t been to the Giants or Jets — and that’s one of the best times we’ve ever had together. I asked her of all the sporting things which was her favorite, and she said the Red Bulls.

“She really liked the supporters’ energy. Very quickly she knew all the chants, wanted go over there, see what it was all about. That’s why I thought it made sense to pledge funding the billboard. I wanted to support the supporters. They’ve been a big part of the experience for my family.’’