But there is a non-statistical basis for concern: an ominous parallel with the financial environment that prevailed in the weeks leading up to the October 1987 stock-market crash. On that day — Black Monday — the Dow Jones Industrial Average dropped 22.6% in a single session.

In trade-related moves, the US currency gained ground on the Swiss franc after Trump set a 39% tariff rate on Swiss imports, up from the 31% he previously mooted. Canada’s dollar dipped to a more than two-month trough after the country received a 35% levy instead of an earlier threatened 25%.