Local stocks extended losses for a third straight day, weighed down by the gold and financial sectors. That tracked a decline by global equities as commodity markets weakened.
At 1545 GMT, the rand had slipped 1.68 percent to 15.5670 per dollar, its weakest in 2 1/2 weeks, as the dollar recovered from profit-taking earlier in the day..
The dollar was up 0.27 percent measured against a basket of major currencies.
Government bonds fell, with the yield on benchmark debt due in 2026 rising 8.5 basis points to 9.645 percent.
South Africa's trade balance swung to a 1.77 billion rand ($115 million) surplus in November from a revised 21.6 billion rand shortfall in October, which had driven the rand to record lows.
However, the surplus failed to strengthen the currency. A return of dollar appetite globally left the rand at its weakest since Dec. 14.
Credit and money supply data due on Thursday present further risks for the rand. A Reuters poll of economists expect the figures to show Africa's most advanced economy continues to struggle.
Trade was muted on the stock exchange, with only 938 million shares changing hands, according to preliminary data, well below last year's daily average of 183 million shares.
Anglo American Platinum was the biggest loser among the blue chips, shaving off 5 percent to close on 181.19 rand.
Merchant Insurance Holdings lost 3.41 percent at 38.19 rand and FirstRand gave back 2.68 percent at 42.56 rand. Investment firm Brait shed 3.07 percent at 162.35 rand.
The benchmark Top-40 index dropped by 0.21 percent to 45,900.83 points. The broader All-Share index was down 0.31 percent at 50,805.13 points.