March 27 (Reuters) - Shares of Trump Media & Technology Group rose more than 18% on Wednesday, extending gains from their stellar Nasdaq debut to the second day.

It was the fifth most-trending stock on retail trader-focused platform Stocktwits and among the 15 most-traded stocks across U.S. exchanges at 9:40 a.m ET, according to LSEG data.

The rise underscores the popularity of Donald Trump driving investor interest, but the platform Truth Social would need to show strong user growth to sustain the trajectory, analysts said.

"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.

At $68.56, TMTG has a market capitalization of $9.29 billion on an undiluted basis and that has boosted the value of Trump's stake to about $5.40 billion.

Truth Social has 8.9 million signups, according to a regulatory filing on Feb. 14, and does not break down the active users figure.

In comparison, X had 238 million daily active users as of June 2022, as per the latest available official data, while Facebook and Reddit had 2.1 billion and 73 million, respectively.

Digital World and the newly listed TMTG have surged about 600% since their merger was announced in 2021, cementing TMTG's status as one of Wall Street's so-called meme stocks. (Reporting by Yuvraj Malik in Bengaluru; Editing by Arun Koyyur)