At noon AEST on Friday, the benchmark S&P/ASX200 index was down 107.2 points, or 1.33 per cent, to a one-week low of 7,929.3, while the broader All Ordinaries had dropped 107.2 points, or 1.3 per cent, to 8165.5.
The day was on track to be the ASX200's worst since a similar 1.33 per cent drop on June 11, but the index was still set to finish the week down just 0.26 per cent following gains of 0.7 per cent on both Monday and Wednesday.
There was no obvious reason for the sell-off, which may simply be from profit-taking after days that had left the ASX200 at an all-time high.
Overnight, the S&P500 dropped 0.8 per cent and the Dow Jones fell 1.3 per cent amid a rotation out of tech stocks.
At midday, every sector of the ASX was lower except for telecommunications, which was up marginally.
The materials/mining sector was down nearly two per cent, as prices dropped for base metals, especially copper and tin.
BHP was down 1.9 per cent, Fortescue had fallen 2.1 per cent and Rio Tinto was down 1.8 per cent.
Goldminers were also in the red as the precious metal traded for US$2,424 an ounce, down from Wednesday's all-time high of $US2,483.
Northern Star had dropped 2.0 per cent and Evolution had slipped 3.8 per cent.
All of the big four banks were lower, with ANZ falling 2.1 per cent, Westpac and NAB both dipping 1.5 per cent and CBA retreating 1.2 per cent.
At midday, Lifestyle Communities was the worst performer in the ASX200, falling another 13.6 per cent to a nearly four-year low of $9.55 after the retirement community operator withdrew its forward guidance following a critical story by ABC's 7.30.
Lifestyle Communities said on Friday that the media coverage had focused on the exit fees that community members pay to leave, while not considering the lower prices homeowners pay to live in its communities.
The company said it had asked the Victorian Civil and Administrative Tribunal to hear a case brought by some disgruntled homeowners as soon as possible.
On the flip side, Universal Store Holding was up six per cent to $5.79 after the youth fashion retailer reported unaudited sales of $288.5 million in 2023/24, up 9.7 per cent from the previous year.
Chief executive Alice Barbery credited enhanced execution, rather than favourable macroeconomic conditions, which she said were still challenging.
Droneshield was up 8.1 per cent to $1.87, on track to finish the week down 20.2 per cent, but still up fivefold for the year.
The Australian dollar was at a more than two-week low against its strengthening US counterpart, buying 67.05 US cents, from 67.40 US cents at Thursday's ASX close.