The longed-for moment is almost here. For two and a half years, ever since America’s Federal Reserve embarked on its fastest series of interest-rate rises since the 1980s, investors have been desperate for any hint of when it would reverse course. Now it would be a huge surprise if Jerome Powell, the central bank’s chair, did not announce the first such reduction after its rate-setting committee meets on September 18th. Indeed, among traders, the debate is no longer “whether” but “how much”. Market pricing implies roughly a 40% chance that officials will cut their policy rate, currently between 5.25% and 5.5%, by 0.25 percentage points, and a 60% chance that they will instead opt for 0.5.