Investors pulled record amounts of cash out of equity funds during the third quarter amid concerns that an AI-fuelled boom in share prices could be poised for an abrupt halt.

More than £3.6bn flowed out of equity funds over the last three months, figures from Calastone show, with £1.2bn withdrawn in September alone.

Investors ran scared of “sky-high stock markets”, according to the data company’s latest Fund Flow Index.

The FTSE 100 and the S&P 500 ended last week at fresh record highs despite the turmoil caused this year by Donald Trump’s tariff campaign.

Excitement about the prospects of AI have driven markets higher, particularly in the US. On Monday, ChatGPT maker OpenAI announced a chip supply deal with AMD, sending the latter’s shares up 24pc.