The benchmark S&P/ASX200 index was down 18.6 points, or 0.28 per cent, to 6,610.7 at noon on Wednesday, while the broader All Ordinaries retreated 14.5 points, or 0.21 per cent, to 6,803.6.
The energy sector was the biggest laggard as Brent crude dropped 9.0 per cent to a two-month low of $US102 on fears a global recession will kill demand.
The sector was down by 4.2 per cent, with Woodside down by 5.4 per cent, Santos by 4.3 per cent and Beach Energy by 6.7 per cent.
The heavyweight mining sector dropped 3.7 per cent, with BHP falling 4.3 per cent to a seven-month low of $38.29, Rio Tinto down 5.2 per cent to an eight-month low of $95.55 and Fortescue retreating 4.9 per cent to an eight-and-a-half month low of $16.48.
Goldminers were also under pressure as the price of the precious metal dropped under US$1,800 an ounce for the first time since February, as rising interest rates crimp demand for the non-yield bearing asset.
Newcrest was down 5.2 per cent, Northern Star fell 3.3 per cent and Evolution dropped 4.4 per cent.
The tech sector was up 3.4, putting it on track for its best day in a week and a half following an overnight rally among US tech giants.
Xero was up 6.1 per cent, Wisetech Global climbed 5.3 per cent and Afterpay owner Block was up 4.7 per cent.
Both consumer discretionary and staples were up by close to 2.0 per cent, with Woolworths rising by 2.5 per cent and Domino's climbing 4.9 per cent.
The big banks were higher, with NAB the best performer, rising 1.3 per cent to $28.01.
The Australian dollar was buying 68.09 US cents, from 68.57 US cents at Tuesday's close, as the greenback surged against other currencies.
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