It has been a nervy few days for financial markets.
A sell-off in bond markets, prompted by monetary tightening in America, this week infected global stock markets, too.
The S&P 500 share-price index fell by over 3% on October 10th, its worst day in eight months.
Markets in Shanghai hit their lowest level for nearly four years the next day; those in Japan and Hong Kong closed around 3.5% lower.
At first glance, the sell-off seems odd. The world economy is still growing briskly enough:
this week the IMF only slightly trimmed its forecast for world GDP growth for 2018, from 3.9% to 3.7%. But investors are right to fret.
Whereas acceleration was synchronised across much of the world in 2017, the global economy's expansion now looks increasingly unbalanced.
Two divides stand out. The first is between emerging markets, which are suffering from particularly volatile financial conditions, and advanced economies.
The cause of this divergence is a strong dollar, which is making emerging markets' debts that are denominated in the currency costlier to service.
The latest casualty is Pakistan. On October 8th it announced that it would seek an IMF bail-out, which is expected to amount to $12bn.
It joins the ranks of other emerging markets in distress, notably Argentina, which has negotiated a record $57bn credit line from the IMF, and Turkey.
Sustained falls in emerging-market currencies and stocks have been painful for investors. Several countries have raised interest rates to stem capital outflows.
Yet the damage to the real economy has for the most part been confined to those with large current-account deficits, such as Argentina.
From a global perspective, the bigger worry is China.
Authorities there are trying to reduce leverage in the financial system at the same time as American tariffs are squeezing their exports.
The currency is under pressure; growth expectations are being lowered.