Companies with exposure to the United States economy bucked the trend by showing strong gains.
At 12pm AEDT, the benchmark S&P/ASX200 index was down 18.6 points, or 0.4 per cent, at 4674.6 while the broader All Ordinaries had lost 12.1 points, or 0.26 per cent, to 4681.6.
On the Sydney Futures Exchange, the December share price index contract was three points higher at 4686, on a volume of 9395 contracts.
Austock Securities senior client adviser and strategist Michael Heffernan said investors were predictably taking a break after the market's strong surge in recent weeks.
"Last week was up over two per cent ... so I think it's just pause on a strong upward march," he said.
The major banks were subject to profit taking after their strong gains.
ANZ Banking Group was down 29 cents at $22.89, National Australia Bank lost 46 cents to $29.40, Westpac was 19 cents lower at $24.72 and Commonwealth Bank was down five cents at $49.04.
The big miners were also weaker with BHP Billiton 44 cents lower at $38.26 and Rio Tinto fell 21 cents to $60.79.
Rio's Alcan division said today it is cautious about the short-term aluminium market but the company remains bullish on growth during the next two decades.
Rio has also completed the $US750 million ($A859.35 million) sale of the Corumba iron ore mine in Brazil to Vale SA.
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