China’s collapsing investment is as unprecedented as it is hard to explain.

A plunge estimated at more than 11% in October from a year earlier was the worst single-month performance since the initial Covid lockdowns at the start of 2020, official data showed on Friday. A further crash in investment could prove destabilizing by affecting an activity that makes up nearly half of China’s gross domestic product, driving up risks for an economy already coping with a downswing in exports.