Mark Cuban joined Reddit’s WallStreetBets for an “Ask Me Anything” session on Tuesday and, true to form, he didn’t hold back.

The billionaire has been among a group of prominent financial heavyweights, including Chamath Palihapitiya and Cameron and Tyler Winklevoss, to align with retail traders in what they see as a battle between Main Street and Wall Street.

During the chat, Cuban encouraged the forum to hold on to their GameStop Corp. shares if they could afford to do so, and predicted that institutional funds would jump back in for a second round of shorting the video-game retailer (click here to see Cuban’s responses). The serial entrepreneur and reality television star said GameStop holders should take a lesson from Bitcoin investors who held on to the cryptocurrency when its price plummeted in 2017.

“I have no doubt that there are funds and big players that have shorted this stock again thinking they are smarter than everyone on WSB,” said Cuban, who doesn’t own the stock. “I know you are going to hate to hear this, but the lower it goes, the more powerful WSB can be stepping up to buy the stock again.”

‘Big Way’

The owner of the NBA’s Dallas Mavericks also took shots at Robinhood Markets for, in his words, failing its users.

“There was only one thing that messed you all up: Robinhood and the other zero commission brokers that everyone used didn’t have enough capital to fund the fight,” he wrote. “They let you down in a big way.”

Robinhood clients are currently only allowed to purchase restricted amounts of shares in certain securities. Users are limited to buying 100 shares of GameStop and 1,250 shares of AMC Entertainment Holdings Inc., for example.

But it wasn’t just Robinhood that attracted Cuban’s ire. He attacked the U.S. Securities and Exchange Commission for not caring about ordinary investors, saying he “wouldn’t trust them to do the right thing ever.”

Short Target

Cuban also spoke about this own experience of being the target of short-sellers. Back when his company, Broadcast.com, was public he said he encouraged people to short the stock if they didn’t believe in it. Now, he said, he loves to see the companies he owns being shorted.

“If it’s a company I want to own, I know the shorts can be squeezed and if the company does really, really well, then the shorts will have to cover, creating more demand for the stock of the company I own, pushing the stock price up,” Cuban wrote.

Cuban, who’s worth US$4.9 billion, according to the Bloomberg Billionaire Index, told WallStreetBets’ members to keep sticking it to the establishment and to find a better broker for the next time.

“Thanks for changing the game. Thanks for taking on Wall Street,” Cuban wrote, urging them to find “a broker with TRILLIONS OF DOLLARS in assets on their balance sheet. Someone that can be there when the fight starts and won’t blink an eye.”