The sharemarket is one per cent lower at noon as investors remain concerned about China's economy and falling commodity prices.
IG Market analyst Stan Shamu said growing concerns about China and a significant drop in the copper price overnight had not helped sentiment.
"It shows a bit of an acceleration of the trade that's been going on since the beginning of the week after that disappointing Chinese trade data," Mr Shamu said.
"It's compounding views that China is slowing down in the short term, with analysts feeling it won't reach its growth targets."
Recent data from China show an unexpected trade deficit, due to a big fall in exports. February's $US23.0 billion ($A25.52 billion) deficit was a shock after analysts had forecast an $US11.9 billion surplus.
A sharp fall in iron ore prices has also dominated trade so far this week, but the price stabilised at US$105 overnight.
Banking and mining stocks suffered some of the biggest falls on Wednesday morning.
BHP Billiton was down 34 cents at $35.59, Rio Tinto had dropped 27 cents to $60.93, but Fortescue Metals was up 12 cents at $4.95.
Most other sectors of the market were lower, including the financials.
Among the major banks, Westpac had lost 54 cents to $33.75, Commonwealth Bank was down 71 cents at $75.53, ANZ had dropped 42 cents to $31.92 and National Australia Bank was 33 cents weaker at $34.44.
Telstra was flat at $5.07.
* At 1200 AEDT on Wednesday, the benchmark S&P/ASX200 index was down 58.7 points, or 1.1 per cent, at 5,355.1 points.
* The broader All Ordinaries index was down 58.1 points, or 1.07 per cent, at 5,371.2 points.
* The March share price index futures contract was down 63 points at 5,352 points, with 8,659 contracts traded.
* National turnover was 574 million securities worth $1.3 billion.