The reception area of the Johannesburg Stock Exchange. File picture: Leon Nicholas

Johannesburg - South African stocks ended a see-saw session marginally lower on Monday, pulling back from three-week highs in the day as cautious investors digested comments from US Federal Reserve chair Janet Yellen.

The US central bank's “extraordinary” commitment to boosting the economy, especially the still-struggling labour market, will be needed for some time to come, Yellen said in her first public speech since becoming Fed chair two months ago.

Analysts do not expect the Fed to pull back on a decision to taper bond purchases that have boosted emerging markets such as South Africa.

Johannesburg's blue chip JSE Top-40 index inched down 0.4 percent to 42,996.63.

The broader All-share index also edged down 0.33 percent to 47,770.92.

“Her comments were very dovish. That was the reason why we have come back,” said Brandon Sacks, a sales trader at Avior Research in Johannesburg.

The market would experience some more volatility this week and end flat or marginally lower, he said.

Telecoms giants Vodacom and MTN were in nosebleed territory after a Johannesburg High Court ruled that the industry regulator can go ahead with interconnection rate cuts that will hurt their revenues.

Vodacom lost nearly 2 percent to 129.99 rand and MTN was down more than 1 percent at 215.55 rand.

Telkom SA, which had been down for most of the day, turned positive by the close. It stands to gain from the ruling, alongside unlisted No. 3 operator Cell C.

Advancers outnumbered decliners 171 to 10 with 55 issues unchanged.

An average 225 million shares changes hands, according to preliminary bourse data. - Reuters