Stocks ended slightly higher, with Steinhoff in demand a day after a fraud investigation in Germany sent its shares tumbling nearly 10 percent. Steinhoff has denied any wrongdoing.

At 1552 GMT, the rand traded at 13.0325 to the dollar, up 1.38 percent from its Thursday close in New York.

In the absence of domestic events, local traders were closely following Yellen's speech.

"It's all dollar weakness more than anything else," said TreasuryOne currency dealer Phillip Pearce.

"Everybody was hoping that (Yellen) would say something about monetary policy. The fact that there was nothing about monetary policy has weakened the dollar."

Investors were not expecting Yellen to make a policy statement but some market participants were hoping for some signal at least on the Fed's planned balance sheet reduction, if not on the outlook for US interest rate hikes.

Instead, Yellen focused on US financial reforms.

In fixed income, the yield for the benchmark government bond due in 2026 closed 1.5 basis points lower at 8.57 percent.

The JSE Top-40 index added 0.15 percent to 50,175 and the broader All-share index gained 0.12 percent to 56,655.

Steinhoff featured on the gainers' list, rising 2.9 percent to 61.30 rand after dismissing a report from a German magazine that its chief executive is among those investigated for an accounting fraud.

Steinhoff, Europe's second-largest furniture retailer after IKEA, said substantial facts and allegations in Manager Magazin's report were wrong or misleading.