To him, there are reasonable explanations why people could be somewhat excited about GameStop. One of its newest board members, Ryan Cohen, helped turn Chewey into one of the largest online pet product sellers in the world, before selling it to PetSmart. GameStop’s also on a track to being profitable again.

But that doesn’t come close to explaining GameStop’s share price now. “It’s a Ponzi scheme,” Pachter said, referring to a form of fraud that appears to make money but in fact is only propped up by funding from new investors. “There is a point where it’ll go down.”

He suspects that may happen after the company reports its quarterly results in March, at which point executives and investors on the board are allowed to sell their shares.

In the meantime, the social media hype is continuing on Reddit, where users are declaring their intention to buy and hold more GameStop shares, all to send prices even higher.