The Australian bourse continued losing at Friday noon, after a weak start led by losses on Wall Street overnight and disappointing profit results.

At midday (AEST), the benchmark S&P/ASX200 index shed 45.2 points or 1.01 per cent at 4433.8. The broader All Ordinaries index, meanwhile, had slumped 44.2 points or 0.98 per cent to hit 4465.4.

On the Sydney Futures Exchange, the September share price index contract was 48 points weaker at 4406, on volume of 13,897 contracts.

Global markets losses due to US unemployment figures were weighing the market down, according to Austock Securities senior client adviser Michael Heffernan.

But on Wall Street's reaction to the news, he said "I think the Americans have overdone it ... on the basis of those labour market figures."

"To make it comparable in Australian terms, it'd be less than if 1000 people applied for unemployment benefits. That's hardly something to get you all in a lather, frankly."

Mr Heffernan said the continuing uncertainty surrounding BHP Billiton's takeover bid for Potash Corp of Saskatchewan was also dragging down the market.

BHP stocks lost 50c at $37.80 by 12.10pm.

Other mining giants followed suit with Rio Tinto shedding $1.65 or 2.25 per cent at $71.53 and Fortescue Metals sliding 6c at $4.58.

On the retail sector, Mr Heffernan said Billabong could be a good buying opportunity after shares in the surfwear brand were down 88c, or 9.88 per cent, at $8.03 when it reported full year net profit and revenue losses.

The financials, with the exception of ANZ, also suffered losses.

At 12.17pm, Commonwealth plunged 65c at $49.71, Westpac slumped 42c at $22.52 and National Australia Bank shed 52c, or 2.13 per cent at $23.88.

ANZ shares climbed 29c, or 1.29 per cent, at $22.69, after it announced an unaudited underlying profit after tax for the nine months to June 30 of around $3.6 billion, up 26 per cent on the previous equivalent period.