Why did so many world markets sell off on Tuesday? On the surface, there are similarities to the Asian crisis of 1997, which gave markets the word “contagion” – financial and currency crises spread from one country with weak economic fundamentals to another, until European and US markets also suffered.

This time, however, several analysts suggested that the cause was slightly different. Rather than contagion starting in China, where markets fell 9 per cent on Tuesday, they suggested that there was a correlated fall that involved many different assets that appeared over-valued and, therefore, unattractive for investors who had become more nervous about economic risks.