The correlation between the movement of big US stocks is at the highest level since Black Monday in 1987, with price moves increasingly driven by the ebb and flow of investors’ fears over the economic environment.
Stocks, in theory, should move in individual directions based on company fundamentals. But markets of late have been characterised by mass selling alternating with waves of buying, as investors upgrade or downgrade the risk of the US slipping into recession, or a financial crisis sparked by a European sovereign default.
The correlation between the biggest 250 stocks in the S&P 500 over the past month has reached its highest since 1987 this week, at 81 per cent, according to JPMorgan figures.