Financial markets have tumbled amid fears that an uptick in coronavirus cases will hurt the economic recovery.
In the US, the three main financial indexes saw their worst day in weeks, with the Dow Jones Industrial Average down almost 7%.
The decline came a day after America's central bank said the US faces a long road to recovery.
They follow a weeks-long rally that had helped shares recover some ground from March lows.
Energy and travel stocks were among the biggest losers, as oil prices also took a hit.
Earlier, European and Asian shares also dropped, with the UK's FTSE 100 sinking about 4%. In Germany, the Dax fell 4.4%, while in France the CAC 40 ended 4.4% lower.
Source:
BBC