Remember the dotcom boom? Gregory Perdon of private bank Arbuthnot Latham does. As its co-chief investment officer, he worries that 2019 feels a bit like 1999: "In the late 1990s, taxi drivers in New York would tell me which call options they were buying on which tech stocks — it was euphoric back then. I don't think we are at those levels just yet but, equally, I don't think we are a million miles away."

In fact, some argue that the only real difference is that the taxi drivers are now the investment, rather than the investors. Last month's initial