GameStop stock and AMC Shares soared Monday after Keith Gill, who sparked the meme stock rally during the pandemic, made his return to social media for the first time in three years. The New York Stock Exchange temporarily paused trading on GME stock multiple times early Monday as shares careened higher.

Gill, known by his social media name Roaring Kitty, on  sunday night posted on social media platofrm X for the first time since June 2021. The post was an image of a meme implying he is “getting serious.”

Gill rose to infamy in 2020 and 2021 as one of the key drivers for the GameStop  short squeeze. The former financial broker and analyst was eventually called to testify in front of the House Financial Services Committee in February 2021 regarding a probe on potential market manipulation.

Retail investors celebrated with comments like “he’s back,” and “game on,” or “just in time for the memecoin supercycle,” in a reference to rising prices for smaller cryptocurrencies.

GME stock vaulted about 74.5% Monday following the post. The NYSE briefly paused trading on GME stock multiple times within the first hour or so of trade Monday due to volatility.

GameStop shares were essentially flat on the year through Friday, closing at 17.46.

Theater chain AMC Entertainment rallied 78.4% Monday. AMC stock has dived nearly 53% in 2024 through Friday. Shares are not too far above their record low of 2.38 from April.