GameStop Corp's Frankfurt-listed shares trebled at one point on Thursday, overshooting the videogame retailer's 100% surge on Wall Street overnight, as European retail traders joined in the fresh buying push.
GameStop shares rose as much as 240% in premarket trading and were up 210% as of 0741 GMT.
The surge comes after a couple of weeks that saw the shares move in relatively tighter ranges.
"It's a marathon, not a sprint. Whatever happens resist the urge to sell. The longer we hold the higher it goes," said @catchme1fyoucan, one user in Italy of the retail trading platform eToro, in a discussion on GameStop.
Analysts could not pinpoint one reason for the sharp move, but at least one ruled out a short squeeze that had fired the "Reddit rally" in January when amateur investors piled into stocks that hedge funds had bet against.
Some Twitter users cited factors including options trading and the resignation of GameStop Chief Financial Officer Jim Bell, announced on Tuesday.
GameStop's US-listed shares soared nearly 104% on Wednesday and were halted several times in a rally that began after 1930 GMT. They jumped another 85% after hours.
German shares of cinema operator AMC Entertainment, another stock favoured last month by individual traders in online discussion forums such as Reddit's WallStreetBets, jumped 41% following an 18% rise in its US stock on Wednesday.