Lee Cooperman, the founder of Omega Advisors, has joined the growing chorus of investors blaming last week's stock market sell-off — and his own poor performance in August — on esoteric but increasingly influential trading strategies pioneered by hedge funds like Bridgewater.

In a letter to investors on September 1, Mr Cooperman and his partner Steven Einhorn said fundamental factors such as China's ructions and uncertainty over the US interest rate outlook "cannot fully explain the magnitude and velocity of the decline in equity markets last month".