While Wall Street’s stroker of beards muttered something about AI, and weak manufacturing data prompting fresh fears about the economy, it was pretty clear they were clueless about the reason, as all the companies besides Intel had posted great quarterly results.

The worst hit was Nvidia. There was no company-specific news; it just appeared that investors are questioning valuations in the sector after Nvidia's second-quarter report last week beat estimates but by less than expected. Nvidia tumbled a record $279 billion and lost 9.5 per cent — the biggest single-day loss ever recorded by a US company.

This knock-on effect on TSMC fell five per cent because it has traditionally followed Nvidia for some reason.  AMD fell 7.82 per cent, for pretty much the same reasons. Intel, which was already having a bad week fell 8.80 per cent.

By the afternoon, it appeared that Wall Street had convinced itself that the fall was not about weak manufacturing data, but there was an AI bubble bursting, and dealers went on a witch hunt, searching for anyone who had dared to mention AI in a press release in the last year.

Ironically, Apple, which has yet to release an AI product, lost 2.75 per cent of its value because the Tame Apple Press has been talking up its unreleased AI products as if they were going to save the company and humanity. Microsoft, one of the key players behind AI, lost 1.75 per cent.  

September is always a rough time for tech companies, and investors are traditionally jittery. However, other than Intel, there is nothing to suggest any of these companies are overpriced or will not regain their value when the share brokers wake up in a couple of weeks with their minds changed.