The JSE was straight into red territory at its opening on Monday tracking negative global sentiment.
A local trader said that investors would eye US futures for direction with US earnings season well under way.
By 09.26am local time the JSE all share index had shipped 53% as resources lost 0.46%, platinum miners declined 1.23%, and gold miners were 0.22% weaker. Banks gave up 0.60%, financials dropped 0.59% and industrials shed 0.56%. Gold was quoted at $1 191.57 a troy ounce from $1 192.80/oz at the JSE's previous close, while platinum was at $1 512.50/oz from $1 516.50/oz before.
A trader said: "We saw Wall Street end lower on Friday, and that performance trickled into Asia, although some markets are on holiday there. Markets will eye US futures for direction during the course of the morning with some corporate earnings due later."
The trader said that Ireland's downgrade only added to current negative sentiment in Europe, while the economic outlook in the US also remains tentative.
Dow Jones Newswires reported that Moody's Investor Services on Monday cut Ireland's credit rating, citing a rising debt burden, a weak growth outlook and the high cost of rebuilding a shattered banking system.
Regional markets in Asia were mostly lower with the Hang Seng giving up 1%, and the Composite Index 0.22% lower. Japan's markets were closed.
On the JSE, Anglo American plc dropped R2.22 to R272.71 but BHP Billiton added 19 cents to R211.69. Sasol declined R2 at R278.