Gamestop chain's stock surged 90% in early Wall Street trading after new cryptic messages in social media.
But the rally eventually fizzled out. The stock closed Monday at a 21.0% gain.
Keith Gill, known as "Roaring Kitty," continues to influence the stock's price movements.
His latest post came on the social media platform Reddit on Sunday. The post consists of a screenshot showing that Gill, who calls himself DeepF on Reddit, has traded Gamestop shares and options worth $116 million, equivalent to $1.2 billion.
As a result, the stock rose as much as 105% in Monday's pre-market trading on the US stock exchange, but lost heavily as the day went on.
Gill has also posted a picture of a reverse card from the Uno card game on X. The card changes the direction of the game and the order in which players draw cards.
The upswing is the latest turn in the Gamestop and other so-called meme stocks. Hysteria was revived from its slumber in mid-May after Keith Gill made his first post in years on X. The post consisted of a drawing of a man leaning forward on a chair.
It was a series of posts about Gamestop from the same Gill that in January 2021 triggered a wave of small investors' speculation in meme stocks.