Shares of Trump Media & Technology Group DJT.O surged 17% on Wednesday, extending gains from their stellar Nasdaq debut to the second day, fueled by retail investors including supporters of former President Donald Trump.

Shares of Trump-controlled TMTG, which owns his Truth Social social network, have climbed over 30% since they began trading on Wall Street on Tuesday through a merger with a blank-check company already listed on the Nasdaq.

With the stock last at $67.69, TMTG had a market capitalization of $9.1 billion, lifting the value of Trump’s stake to over $5 billion.

“There is likely to be significant volatility ahead as a share buying frenzy among his supporters may wane, and investors dig deeper into the fundamentals,” said Susannah Streeter, head of money and markets at Hargreaves Lansdown.

Truth Social has about 8.9 million sign-ups. Unlike other social media platforms, it has not publicized how many active users it has.

In comparison, X had 238 million daily active users as of June 2022, per latest available official data.

Reddit RDDT.N has 73 million active users, and its stock market value was about the same as TMTG’s on Wednesday as it dipped 10% in the fifth day of trading since that social media company’s Wall Street debut last week.

Blank-check company Digital World AcquisitionCorp and the newly listed TMTG have surged over 600% since their merger was announced in 2021, cementing TMTG’s status as one of Wall Street’s so-called meme stocks.