In April, after the markets chaos that followed ‘Liberation Day’, Mads Gosvig, who heads asset allocation at the UK’s Railpen pension fund, asked his team to assess the case for an emerging markets premium on US assets.

Gosvig’s intention was to provoke discussion, he says. But the task reflected a genuine disquiet, matched at other pension and sovereign wealth funds, about the behaviour of US investments.

Asset owners are asking whether they should call time on so-called US exceptionalism – the