This autumn the dials on Goldman Sachs’ forecasting machine are spinning in a startling manner. Last month, the US bank’s leading composite indicator of economic growth surged at a record rate – suggesting that western economies will rebound sharply in the second half of this year.

More startling, Goldman’s so-called “financial stress index”, which measures different elements of market health, has recently risen to levels not seen since before the near-failure of Bear Stearns in the spring of 2008.