Reddit Inc.'s stock-trading enthusiasts made it a household name by backing companies that Wall Street wouldn't. For Reddit's own initial public offering, a group of them are about to flip the script.
In the days after the social-media company filed for an IPO, thousands of members of the WallStreetBets forum — which boasts around 15 million users and helped popularize meme stocks like GameStop Corp. — voted to boost a forum post about shorting the company, a sharp reversal of their typically bullish ways. Their avowed reasons varied from the company's lack of profitability to competitive concerns, and mostly centered on spite.
(paywalled on Bloomberg website)
How can I get in on shorting reddit?
You’ll need to approved for a margin account and will need to put up some collateral. It’s not nearly as easy as simply buying stock.
https://www.nerdwallet.com/article/investing/shorting-a-stock
He could also get approval for options trading and buy puts, but puts won't be available until roughly a week of trading, and the IV will likely eat most if not all of his investment.