Short interest on the New York Stock Exchange rose to its highest level since the collapse of Lehman during the month to mid-March and at its highest rate in more than a year as hedge funds increased their bets against the rally in US equities during that period.

From February 27 to Friday March 13, the benchmark S&P 500 index rose about 3 per cent, prompting talk among participants of a lasting rally in the US stock markets, which have been battered by the recession.