All good things must come to an end, including summer holidays and bull markets. The bull run in US shares that began in the aftermath of the financial crisis in March 2009 has now officially passed the previous record of 3,452 more-up-than-down days from October 1990 to March 2000. This time round, the S&P500 index of US stocks has risen by more than 300 per cent — and that rise has continued throughout Donald Trump’s reign, despite his trade war threats and other follies.