Shares were flat on the Australian market after a negative US lead, and the ASX appeared it may struggle for an eighth consecutive positive finish.

The S&P/ASX200 benchmark was down by 1.6 points, or 0.02 per cent, to 6194.1 at 1200 AEDT on Wednesday.

The All Ordinaries index was worse by 0.4 points, or 0 per cent, to 6399.8.

The downbeat US lead came after Johnson & Johnson revealed it had paused a study for a COVID-19 vaccine after a participant suffered an unexplained illness.

The ASX financials sector was down 0.76 per cent, materials dropped 0.21 per cent and energy sunk the most, 0.96 per cent.

The best sectors were healthcare, up 1.5 per cent, and information technology, up 1.25 per cent.

The healthcare performance was helped after CSL narrowed its guidance on net profit and said it expected growth of three to eight per cent.

Chief executive Paul Perreault told the annual general meeting the previous low end of the range of zero per cent had been revised to three per cent. This would give net profit after tax of $2.170 billion to $2.265 billion this financial year.

Shares were higher by 1.7 per cent to $303.32.

The tech sector improved after financial crimes watchdog AUSTRAC decided it will take no more action against Afterpay following an audit.

An auditor decided Afterpay met anti-money laundering requirements.

The buy-now pay-later company reached a record price of $98.68. It later had a 2.09 per cent gain to $96.44.

In banking, Bank of Queensland posted a fall in full-year profit, due to the economic and social impact of the coronavirus pandemic, but sees better days ahead.

Net profit was $115 million for fiscal 2020, down 61 per cent.

The annual dividend was slashed to 12 cents per share, down from 65 cents in the previous year.

Shares were higher by 3.98 per cent to $6.65.

Among its major rivals, ANZ shed 0.35 per cent to $19.43, the Commonwealth lost 0.79 per cent to $68.83, NAB was down 0.93 per cent to $19.17 and Westpac slipped by 1.52 per cent to $18.67.

Among the miners, BHP dropped 0.05 per cent to $36.29, Rio Tinto lost 0.96 per cent to $95.62 and Fortescue was down 0.33 per cent to $16.56.

Building materials supplier James Hardie Industries raised its full-year profit forecast and says it expects to post record second-quarter results boosted by solid demand for its services across markets.

The company increased its fiscal 2021 forecast for underlying net operating profit after tax (NOPAT) to between $US380 million ($A529 million) and $US420 million, from an earlier projection of $US330 million and $US390 million.

Shares were better by 3.4 per cent to $36.42.

Earlier in the US, all three major stock indexes closed in the red.

The virus study setback coincided with US House Speaker Nancy Pelosi rejecting the $1.8 trillion coronavirus relief proposal from the White House.

The Aussie dollar was buying 71.69 US cents at 1200 AEDT, lower from 71.88 US cents at the close of trade on Tuesday.