Aging populations, as Japan taught us, are inherently deflationary. Folks in their 70s don’t spend the way 20-somethings do. With the unemployment rate for Chinese between 16 and 24 stuck above 17% —or higher given the vagaries of Beijing’s data—what good will subsidies and rebates do?

The unexpected action is intended to tamp down a potential bubble in the bond market fueled by investors shunning riskier assets like stocks and real estate.

China's central bank suspended treasury bond purchases on Friday, briefly lifting yields and spurring speculation it is stepping up defence of the yuan currency which has been sliding since the election of Donald Trump as U.