At 1342 GMT, the rand traded at 18.7100 against the dollar, about 1.2% weaker than its previous close. The rand had gained almost 2% against the dollar on Wednesday after South African inflation data for July came in lower than expected.
The dollar was up about 0.5% against a basket of global currencies, bouncing back from a drop on Wednesday and set for a monthly rise.
Most emerging market currencies were on the back foot on Friday heading into the Jackson Hole symposium, said Danny Greeff of ETM Analytics. Federal Reserve Chair Jerome Powell will speak at the symposium on Friday.
"The market is concerned that central bankers - in particular those representing the Fed - might double down on hawkish posturing at the conference," Greeff told Reuters.
At the BRICS summit in Johannesburg, the group of five developing nations agreed to admit Saudi Arabia, Iran, Ethiopia, Egypt, Argentina and the United Arab Emirates as new members.
South African President Cyril Ramaphosa said the BRICS countries - Brazil, Russia, India, China and South Africa - had reached a consensus on the first phase of expansion and that there would be more candidates, hailing a "new chapter".
On the Johannesburg Stock Exchange, the blue-chip Top-40 index was last trading around 0.1% up from its Wednesday close.
South Africa's benchmark 2030 government bond was firmer, with the yield down 4.5 basis points at 10.245%.
(Reporting by Tannur Anders;Editing by Alexander Winning, Nellie Peyton and Emelia Sithole-Matarise)
