The Australian share market has slumped amid pessimism about global growth prospects and concerns about US-Chinese trade tensions.

The benchmark S&P/ASX200 index was down 51.3 points, or 0.79 per cent, to 6,433.5 points at 1200 AEST on Wednesday, while the broader All Ordinaries was down 49.5 points, or 0.75 per cent, to 6,530.9.

Every sector of the ASX was in negative territory at midday.

The energy sector was hit with the sharpest decline, falling 1.46 per cent, as some investors feared international trade tensions could dent fuel consumption.

Santos, Woodside Petroleum, Oil Search, Origin Energy and Beach Energy were down between 0.33 per cent and 3.19 per cent.

Three of the big four banks were lower, with ANZ down 0.43 per cent to $27.88, Commonwealth down 0.29 per cent to $77.815 and Westpac down 0.88 per cent to $27.625.

NAB was the outlier, rising 0.11 per cent to $26.17.

Mining giant BHP was down 0.67 per cent to $38.34 and Rio Tinto was down 0.82 per cent to $104.445.

Telstra was flat at $3.56 after the telco said it faced an extra $200 million in restructuring costs for the 2019 financial year because of proposed job cuts it was bringing forward.

Bank of Queensland was up 0.65 per cent to $9.30 after it said chairman Roger Davis will step down from his position in October.

On Wall Street overnight, the Dow Jones Industrial Average closed down 0.93 per cent, the S&P 500 was down 0.85 per cent and the tech-heavy Nasdaq Composite was down 0.39 per cent.

Benchmark 10-year US Treasury yields fell to 2.264 per cent overnight – their lowest level since October 2017 – after US President Donald Trump signalled the United States and China were far from a trade deal.

The Aussie dollar is buying 69.24 US cents, from 69.28 US cents on Tuesday.