GameStop Shares Jump After Reddit Legend Keith Gill Doubles Down

The latest large swing in the company’s shares comes after Keith Gill, the man behind the Reddit-driven frenzy in GameStop stock, disclosed a larger stake in it late Friday. A new screenshot posted on Reddit by DeepF---ingValue, his online username, showed that he bought an additional 50,000 shares, bringing his total stockholdings to 100,000 shares, worth roughly $4 million as of Friday, The Wall Street Journal reported.

The aggressive GameStop position has already made Mr. Gill a millionaire and a hero to many individual investors, particularly those on Reddit’s popular WallStreetBets forum.

The latest activity is a sign that the wild ride for GameStop isn’t quite over.

Despite the dwindling stock price, some individual investors have said that they are clinging to their positions, and DeepF---ingValue’s fresh disclosure on Friday earned him praise from fellow Reddit users—and reinvigorated many individual investors.

On Monday on WallStreetBets, some traders talked of buying more GameStop shares.

“IMAGINE NOT BUYING GME WHEN DFV DOUBLE DOWN,” one user, u/CyAn_BryAn, said, referencing the video-game retailer’s ticker symbol and an abbreviation of Mr. Gill’s Reddit username on a GameStop-focused thread that drew thousands of comments.

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Another user commented: “DFV BOUGHT 50K MORE SHARES…That’s enough for me.”

Last week, key figures surrounding the GameStop frenzy, including Mr. Gill, Ken Griffin of Chicago-based hedge fund Citadel LLC and market-making giant Citadel Securities, Robinhood Markets Inc.’s Chief Executive Vlad Tenev and others testified in a House Financial Services Committee hearing on the stock mania.

Mr. Gill reiterated his bullish stance on the stock at the hearing, and his testimony at times appeared to coincide with moves in the retailer’s stock price. He said that even though the stock had notched bigger gains than he initially anticipated, he thought it was still a good buy. The following day, he disclosed the bigger position.

Write to Gunjan Banerji at Gunjan.Banerji@wsj.com and Caitlin McCabe at caitlin.mccabe@wsj.com