On equity markets, banks and retailers were among the worst performing blue-chip firms.

At 1502 GMT the rand was 0.54 percent softer at 13.6200 per dollar compared to its close of 13.5475 overnight in New York.

With no top-tier economic data due locally, focus shifted to Ramaphosa's speech, which comes after the market close, with investors looking for clues about the fate of cash-strapped state power firm Eskom.

In a note, Investec economist Annabel Bishop said expectations were for the speech to focus on key state-owned entities which are under financial pressure, with a formal announcement likely on Eskom's expected restructuring into three separate companies.

She added that the state would was likely to provide further financial support to Eskom in the meantime.

"Buying sentiment towards the Rand will be heavily influenced by the tone Ramaphosa adopts during the SONA," FXTM Chief Market Strategist, Hussein Sayed said in a note.

Bonds also weakened, with the yield on the benchmark government issue due in 2026 adding 0.5 basis points to 8.66 percent.

Stocks dropped, with the Johannesburg Stock Exchange's top-40 index down 1.34 percent at 47,672 points, and the broader all-share index slipping 1.26 percent to 53,888 points.

Truworths lead the declines, down 4.6 percent, with TFG (The Foschini Group), pharmacist Clicks, Nedbank and Woolworths following behind it.

Confidence in firms exposed to South African consumers - whose budgets are tight in a lagging economy - dipped after a series of weak trading updates from big retailers in recent weeks.

Meanwhile, Clover Industries regained some of the ground lost earlier when a minority partner in a consortium that offered to buy the dairy firm said it was reviewing its role in the deal.

Clover shares fell almost 10 percent on the news, but closed just 4.13 percent down.