Nearly as predictable as the phases of the moon, Donald Trump’s protectionist rhetoric continues to wax and to wane. Talk of tariffs has been in the ascendency as we sign off on our latest quarterly forecast, with the comprehensive Sino–US trade deal, which seemed so close in early spring, now but a distant memory. The turning point came on 6 May, days after the S&P 500 had eclipsed its early October peak, when the US President took to the Twittersphere…