Meme stock favourite GameStop is rising again, after a social media post seemingly from the investor known as “Roaring Kitty” claimed a sizeable stake in the video game retailer.

Shares in the firm opened for trade on Monday priced above $40 apiece, up more than 70% from Friday, before later retreating a bit.

The surge followed a screenshot shared by the Reddit account tied to Keith Gill, claiming he owned 5 million GameStop shares – nearly 2% of the firm’s stock – a holding worth more than $100m (£78m).

The post was one of a series in recent weeks that follow a long period of silence from the Roaring Kitty accounts.

The veracity of the post could not be confirmed. Neither Mr Gill nor GameStop responded to emails seeking comment.

Mr Gill became famous in 2021 for inspiring an army of online investors to back GameStop.

It led to an unexpected surge in the struggling firm’s shares, creating a financial squeeze on professional Wall Street firms that had bet against the retailer.

A post from that year showed Mr Gill held about 200,000 shares, worth $30.9m.

Shares in some other so-called meme stocks – whose rise and fall appears disconnected from the fundamentals of the business – also headed higher on Monday, such as AMC and Blackberry.

Analysts had argued the original rise of meme stocks was driven by the surge in savings and time many households had during the pandemic, thanks to government support programmes and the shutdown of many in-person activities.

With markets rising again this year, trading firms such as Charles Schwab and Robinhood have reported another uptick in new accounts and activity by retail investors – people not working for investment houses or other private firms.

GameStop cashed in on the interest last month, raising $933m in a share sale.

But the activity has been a source of some disquiet in the financial industry and in Washington, which hosted hearings on the GameStop phenomenon in 2021.

In an interview last month with business broadcaster CNBC, former financial regulator Jay Clayton, who led the Securities and Exchange Commission under former President Donald Trump, compared it to gambling.

“It bothers me on many levels,” he said. “It’s a lot closer to gambling than it is to trading and it’s certainly not investing.

“Is this something we should be tolerating in our markets?” he added.

“Whether it’s legal or illegal, I don’t think so.”