An X account called Serenity with the handle @aleabitoreddit said in a post that they had taken positions in X-Fab Silicon Foundries SE, a Paris-listed firm with six semiconductor manufacturing sites worldwide. The X account has more than 400,000 followers.

The post, which has more than half a million views, kicked off a retail trading frenzy and sent X-Fab shares higher by as much as 77%. The stock was up by more than 30% in mid afternoon and volumes about 17 times the three-month average. The shares were halted several times due to elevated volatility.

“We have observed the recent increase in our share price and trading volumes,” X-Fab Chief Executive Officer Damien Macq said by email in response to Bloomberg News on Wednesday. “The company is not aware of any undisclosed material developments that would warrant disclosure at this time.”

Bloomberg News has reached out to @aleabitoreddit for comment via a message on X.

X-Fab was also among Wednesday’s most talked-about securities on Boursorama.com, an investor forum owned by Societe Generale.

It’s not the first time this year that a European tech stock has surged on recommendations from @aleabitoreddit, which according to its profile is an “AI/Semi supply chain analyst,” as well as “an AI research scientist.”

The account has previously laid out investment cases for computer maker Raspberry Pi Holdings Plc, wafer maker Soitec and Sweden’s Sivers Semiconductors AB. All these stocks have rallied sharply this year, as investors pile into companies that have exposure to the buildout of artificial intelligence data centers.

Currently trading at about €12 ($14), X-Fab’s stock price is more than double the average analyst price target of about €5.5. Only one out of the eight analysts tracking the stock rated it as a buy, according to data compiled by Bloomberg.

Berenberg analyst Trion Reid downgraded the stock to hold from buy earlier this month, recommending investors to book profits following recent gains.

Such cautious sentiment is shared by Bernstein analyst Alexander Peterc, who rates the stock as market-perform. “X-Fab still looks later than peers to the auto recovery and near-term visibility remains limited,” he wrote in a note dated Tuesday.