At 1515 GMT, the rand traded at 14.2700 against the dollar, roughly 0.8% weaker than its previous close.
JPMorgan said in a note to clients that three factors made the rand look vulnerable: it had reached high levels on an in-house emerging market risk appetite index, key terms of trade were starting to look less favourable and investors might also look at hedging options again soon.
The rand has been one of the best-performing emerging market currencies this year, gaining around 3% against the dollar year-to-date at a time when other units have been under pressure. http://tmsnrt.rs/2egbfVh
Bumper prices for South Africa's commodities exports, in particular metals and precious metals, have helped government revenue collection and supported an economic recovery from the COVID-19 pandemic.
But after strong gains in the past three weeks, some analysts have predicted a reversal.
Shares listed on the Johannesburg Stock Exchange (JSE) slipped on Tuesday after a strong start to the week, as weak platinum prices pulled down the mining companies which had spearheaded most of the gains earlier.
However, local banks, often considered the barometer of the domestic economy, fared well as investors said the worst of the third wave of coronavirus in the country was over and some green shoots were visible.
"It's certainly a little bit better than what anyone anticipated six months ago," said Wayne McCurrie, portfolio manager at FNB, on the prospects of the local economy.
But he cautioned this could be short-lived as falling commodity prices could take the sheen off South Africa and that would reflect on the JSE as well.
The benchmark all-share index ended down 0.54% to 64,300 points and the blue-chip index of top-40 companies closed down 0.65% to 58,115 points.
The mining index was down almost 2%, while the bank index closed up 1.31%.
The yield on the government's benchmark 2030 bond was little changed at 8.895%.
(Reporting by Alexander Winning and Promit Mukherjee, Editing by William Maclean)
