The market initially rallied on Friday, with investors spurred by a strong overnight bounce on Wall Street which followed a rebound in Brent crude oil and iron ore prices.

But it took only 30 minutes for the heat to start coming out of the ASX, and by the afternoon the market was back in negative territory before closing lower for the day, making it nine losses in 10 sessions. The benchmark ASX200 fell 0.3 per cent for the day and 2 per cent for the week to 4892.8, while the broader All Ordinaries slipped a similar amount to 4948.5.

The energy and mining sectors were the hardest hit over the week, dropping by more than 5 per cent. Brent crude oil this week dropped below $US30 per barrel for the first time in over a decade, and is now 18 per cent down so far this year. Iron ore was down 4.5 per cent for the week as at Thursday night, to $US40.22/tonne.

"It's been a pretty ordinary week," said Matt MacDonald, private client advisor at Morgans. "With China devaluing the yuan that means a lot of pressure on US-dollar priced resources and so that had a negative impact on our resources stocks. The dollar is around US69 USc and a negative movement in the currency can also have a negative impact on our market."

However, Mr MacDonald said the news was not all bad. "I think the mood at the moment is cautious, particularly around the resources sector, but upbeat on other sectors. The banks are still solid, there's nothing wrong with healthcare.

"My feeling is that we'll stay in this 4900 to 5300 range until we get a little bit more certainty about potential interest rate rises in the US, and China."

Friday's big news was BHP announcing a $US4.9 billion after-tax write-down against the value of its US oil and gas assets. The charge will be reflected in this half's financial results, the company said in an ASX statement.

The company blamed "significant volatility and much weaker prices" for the impairment, and said it had lowered its medium and long-term gas price assumptions.

Analysts said that the BHP write-down was not of major concern to the market.

"Market expectation wasn't that those assets were worth what the book balance was," said Tim Schroeders, who co-manages the resources fund at Pengana Capital.

​"[The writedown] is not really a huge issue in terms of adding to the existing woes of the company.

"Long term, a lot of these commodity prices are unsustainably low at these levels, but the question is how much pain and volatility can you bear between now and when markets move to better and happier times."

CMC chief market analyst Ric Spooner said while many "may regret the timing and pricing" of the write-down, "its reduced value has already been reflected in BHP's lower share price."

"The market is unconcerned about BHP writing down the value of its onshore US assets," he said. "News that BHP will further reduce its rig count is evidence that management remains focussed on cost and risk reduction in response to lower prices."

BHP was up 1.3 per cent for the day but closed 7.8 per cent lower for the week at an 11-year low of $15.07. Competitor Rio Tinto closed 1.7 per cent higher for the day, but 5.7 per cent lower for the week to $39.51.

Among the banks for the week, Westpac was 0.3 per cent higher at $31.09, National Australia Bank dropped 2.5 per cent to $27.01, Commonwealth Bank eased 0.7 per cent to $78.88 and ANZ fell 2.5 per cent lower to $24.91.

The worst-performing stocks for the week included mining and energy names such as Beach Energy, Fortescue, Western Areas, Santos, AWE and Whitehaven Coal, all of which lost between 10 and 20 per cent.

The worst performer was shipbuilder Austal, down 28.1 per cent to $1.03, after reports the US navy is spending millions of dollars to repair the company's new high-speed transport ships because their weak bows can't stand buffeting from high seas.

The best performer on the ASX 200 was JB Hi-Fi, up 6.5 per cent to $21.51, as investors bet the retailers stands to benefit from the potential closure of dozens of Dick Smith stores.