The number of very rich people in the US grew last year at the fastest pace in at least a decade as their moves into international stockmarkets, real estate and alternative investments paid off.

The number of households with $5m (€4m) or more in investable assets – excluding the family home – rose by 26 per cent to a record 930,000, according to a study by Spectrem Group. That is the biggest jump since Spectrem began its survey in 1996. The number of millionaires rose by 11 per cent, to a record 8.3m – the second biggest jump in the decade since they were surveyed.