Think Nvidia looks dear? American shares could get pricier still

HOW can you tell it is time to get out of the market? In 1929, Joseph Kennedy, an American businessman and politician, supposedly realised the party was over upon hearing a shoeshine boy dispensing stock tips. In 2000, the exit doors beckoned after 17 dotcom firms paid millions of dollars each for brief advertising slots during the Super Bowl, an American football extravaganza.

And so to a sell signal fit for 2024: Keith Gill is back on social media.

Gill was an architect of the meme stock frenzy of 2021, exhorting retail traders to buy shares in GameStop, a struggling chain of video game shops. After a three-year absence he is posting once again, now apparently in possession of a stake in the firm worth a few hundred million dollars.