By Friday afternoon, the JSE lost most of the gains during the week.
Anglo American Platinum has fallen by almost 9%, while eight insurers and banks are among the companies with the sharpest declines.
The decline on the JSE comes after the US markets closed more than 3% lower on Thursday.
The Dow Jones Industrial Index closed 3.5% lower. The S&P 500 dropped 3.3% or 106 points.
Market volatility increased sharply on Friday, judging by the so-called fear index, the VIX. This index rose by 23%.
The rand opened at R15.69 on Friday morning after weakening by 2% the day before after the shock news that a case of the coronavirus occurred in South Africa.
China is Africa’s largest trading partner, with some 10,000 Chinese firms on the continent.