GameStop (GME) stock soared as much as 110% Monday and was temporarily halted for volatility after “Roaring Kitty,” the person who is seen as the kickstarter of the meme stock frenzy during the pandemic, posted online for the first time since 2021.

“Roaring Kitty,” who was identified that year as Keith Gill, became a prominent figure on Wall Street Bets and YouTube for his bullish stance on GameStop (GME).

Sunday’s post on X included a meme of a video gamer leaning forward, appearing to take the game seriously. The last time Roaring Kitty posted on X was in June 2021.

Gill was known for posting commentary about why GameStop would go higher and eventually testified before Congress about the massive January 2021 short squeeze spurred by an army of retail traders.

Short interest on GameStop sits at around 24% of the float, according to S3 Partners data.

“Including today’s losses, GME shorts are now down -$1.34 billion in May month-to-date losses, and now down -$952 million for the year,” Ihor Dusaniwsky, managing director of S3 Partners, told Yahoo Finance on Monday.

Monday’s gains follows a recent rally in meme related stocks. Theater chain operator AMC (AMC) gained 19% during the session while Trump Media & Technology (DJT) gained 8%.

“Short sellers may be in for a bumpy and bloody ride in these stocks,” said Dusaniwsky.

As Yahoo Finance’s Jared Blikre recently noted, the recent meme stock surge doesn’t appear to be the ominous signal it has been in the past, but rather a healthy risk appetite for investments.

Ines Ferre is a senior business reporter for Yahoo Finance. Follow her on Twitter at @ines_ferre.