At noon on Friday the benchmark S&P/ASX200 index was down 35 points, or 0.53 per cent, to 6521.1, while the broader All Ordinaries was down 40.9 points, or 0.6 per cent, to 6719.7.
With just a few hours of trading left, the ASX200 was down 6.5 per cent for September, meaning it will likely suffer its biggest drop since a 8.9 per cent decline in June.
The index was also down 0.8 per cent for the week, putting it on track for its third straight losing week, as well as its fifth weekly decline in the past six weeks.
Every sector was in the red at midday except for energy and mining, which had climbed 0.3 and 1.3 per cent, respectively, as the US dollar ebbed again following its recent rampage.
BHP had risen 2.0 per cent to $38.915, while Fortescue Metals was up 0.5 per cent to $16.865 and Rio TInto had added 3.7 per cent to $94.29
Goldminers Newcrest, Northern Star and Evolution were all up between 3.9 and 4.9 per cent as the price of the precious metal continued to recover after hitting a two and a half year low last week.
All the big banks were lower, with CBA down 1.2 per cent to $91.97, Westpac falling 1.0 per cent to $20.90, ANZ down 0.6 per cent to $23.225 and NAB dipping 0.3 per cent to $29.18.
Tech stocks were the biggest drag on the index, falling 1.9 per cent. Wisetech Global had fallen 3.7 per cent to $53.06 and Xero was down 3.8 per cent to $74.09.
