• GameStop’s stock has exploded in the past week, surging more than 800%.
  • Chewy cofounder Ryan Cohen’s 12.9% stake, acquired in August 2020 for $76 million, is now worth nearly $3.1 billion.
  • Members of a Reddit forum dedicated to playing the stock market have boosted the stock to an all-time high.

One month ago, GameStop announced to shareholders that it would close more than 1,000 stores by the end of March.

Since then, the video-game retailer’s stock has skyrocketed by more than 1,900%, with some 800% occurring in the past week alone. The company can thank a Reddit forum, named “Wall Street Bets,” for this massive rally. The forum has more than 2 million members, largely committed to buying the stock at this point in time. (It didn’t hurt that Elon Musk tweeted “Gamestonk!!” during after-hours trading on Tuesday).

Redditors are posting screenshots of their paper gains from the rally, but the biggest winners aren’t boasting online. GameStop’s three biggest individual shareholders gained $4.1 billion combined since January 20, as calculated by Insider using SEC filings.

The biggest beneficiary from the stock surge is Ryan Cohen, the cofounder of pet-food e-commerce firm Chewy, who made a $76 million investment in GameStop last August. His 12.9% stake is now worth nearly $3.1 billion – up from $352 million on January 20 – based off a price of $340.42 at 1:00pm ET Wednesday. The 35-year-old sold Chewy to PetSmart for $3.35 billion in 2017, which was the largest e-commerce acquisition in history at the time.

Cohen also recently joined GameStop’s board.

The second-biggest winner is Donald Foss, who bought a 5.3% stake last February for about $12 million. His stake is now worth $1.2 billion. The founder of subprime auto lender Credit Acceptance Corp. has a total fortune of $2.5 billion, with his net worth increasing more than $660 million since market close on Tuesday, per Forbes data.

GameStop CEO George Sherman's 1.2 million shares are now worth $400 million. If stock continues to rise at this rate, he could be a billionaire in a matter of days.

Representatives for Cohen, GameStop, and Credit Acceptance Corp. did not immediately respond to Insider's request for comment.

E-commerce entrepreneur Attal Alain joined GameStop's board on January 10 just in the nick of time. His 125,000 shares, worth $4.9 million when reported to the SEC on January 19, are now worth $42.6 million.

Wedbush Securities Managing Director Michael Pachter has written off the rally as "a cult phenomenon."

"They don't currently have the earnings power to support a price this high," Pachter told Insider. "The market appears to believe Ryan Cohen has a strategy that will take earnings up by a lot. I can't give him credit for his genius until I see what the strategy is."

[Editor's note: This article's headline was changed to reflect that Ryan Cohen's GameStop stock increased by $2.7 billion in value and is now worth $3.1 billion. It did not increase by $3.1 billion in value.]