The Australian market was lower at noon, with investors worried about global economic growth dragging down cyclical resources stocks.
One reason for that is the release of HSBC Bank figures on Thursday morning showing manufacturing activity in China slowed last month, which supports the Chinese government's own numbers released on Wednesday.
Weaker commodities prices in offshore trade, especially in oil and copper, were affected by the latest Chinese data plus a steady recent flow of poor economic indicators out of the US and China.
"Low commodity prices are weighing pretty heavily on the market at the moment ... it looks like that growth is slowing, which is concerning," Rivkin global analyst Tim Radford told AAP.
"We are constantly seeing this flow of macro data that is quite weak and negative recently, it has consequently led to a reasonable sell off in copper prices for instance in a sign of slowing global economic growth."
Among the mining giants, BHP Billiton has fallen 35 cents to $31.82, Rio Tinto dropped 62 cents to $54.41 and Fortescue had sunk 8.5 cents to $3.395.
Ports and rail operator Asciano shares were also down, 17, cents, or 3.2 per cent, weaker at $5.20.
It flagged slashing about $250 million in spending and cutting jobs after a mixed quarterly update in which volumes fell in its ports container and intermodal rail businesses.
The four major banks are all posting losses so far.
ANZ lost 16 cents to $31.53, National Australia Bank dropped five cents to $33.90, Westpac fell 10 cents to $33.96 and Commonwealth Bank tumbled 45 cents to $72.50.
* At 1240 AEST on Thursday, the benchmark S&P/ASX200 index was down 42.2 points, or 0.82 per cent, at 5,124 points.
* The broader All Ordinaries index was also down 43.9 points, or 0.85 per cent, at 5,100 points.
* The June share price index futures contract was 48 points lower at 5,113 points, with 13,924 contracts traded.
* National turnover was 814.2 million securities worth $1.76 billion.