The world’s economy is slowing down again, uncannily like it did last year. Why? And is this just another soft patch or something more enduring?

Purchasing manager surveys have been accurate leading indicators for output, especially in the US. The May readings uniformly showed growth in manufacturing – in the west, in China, and in South Africa – slowing down, albeit avoiding recession. Even before the latest PMIs, Citigroup’s surprise index, which measures how far economic releases in the G10 exceed or fall below Bloomberg’s consensus expectations from economists, showed data more disappointing than at any time since the credit crisis ended two years ago.

Wednesday’s PMI announcements had immediate market effects: 10-year US Treasury yields fell below 3 per cent for the first time this year, the dollar’s recent revival was squashed, and equities and key commodities (except for gold) fell.