Wall Street’s rapid recovery from its Covid-19 slump has entered a new phase after a leading yardstick of American shares briefly hit a record high.

In early trading in New York the S&P 500, which measures the stock market valuation of the 500 leading US quoted companies, rose to 3,394.82, exceeding its previous high by a single point.

The remarkable turnaround means that shares have risen by 50% since their trough in late March, a period when countries around the world, including the US, were going into lockdown.

Since then, support from the US Federal Reserve has boosted stock market sentiment despite a steady stream of poor economic news, including a near-10% contraction in the American economy in the second quarter of 2020.

Much of the rise in the S&P 500 has been the result of the strong performance of a handful of high-profile companies such as Google, Amazon and Facebook, who have enjoyed a boom in demand during the lockdown.