Metals company Alcoa, weeks away from splitting into two, has reported a quarterly profit that missed estimates and lowered its revenue forecast for the unit serving the auto and aerospace sectors, sending shares down 11.4 per cent.

Quarterly revenue fell in the business making products for the automotive and aerospace industries, due partly to delays with new jet aircraft engines and pricing pressure, Alcoa said.

It posted a higher third-quarter profit as cost-cutting offset lower revenue from curtailed or closed smelting operations and falling prices.

"We are performing well despite the low pricing environment ... demanding conditions on the commodity side as well as aero industry teething problems," Alcoa chief executive officer Klaus Kleinfeld told Reuters. "We have concentrated on what we can influence and you see our strong resilience."

Alcoa will split into two entities ahead of the market opening on November 1. The first company, keeping the Alcoa name, will focus on the traditional smelting business. The other, Arconic, will specialise in higher-end aluminium and titanium alloys for the automotive, aerospace and construction industries.

The company lowered its full-year 2016 revenue targets across all areas of the business, which it said was due to near-term challenges, particularly in the aerospace industry.

The delay in building new, more energy-efficient jet engines stems from the need to test all the metal parts involved, which is taking longer than planned and delaying production.

Charles Bradford of Bradford Research said Alcoa has done "quite well on the cost side" in the third quarter, adding that its problems were largely external, from low alumina prices to the delay in aircraft production.

"The jet engine issue is nothing to do with them," Bradford said. "Demand for those engines is strong, the problem is actually making them."

Alcoa said global automotive production will rise between 1 per cent and 4 per cent in 2016 and that aircraft deliveries will be flat to up 3 per cent in 2016.

Its quarterly results came as benchmark aluminium prices hit two-month highs on Tuesday before retreating on oversupply concerns and rising output by top producer China.

But Kleinfeld said Chinese capacity growth "has not been substantial", adding Alcoa sees aluminium demand increasing 5 per cent in 2016, outpacing supply growth of 3 per cent.

He said the continued "aluminiumisation" of the auto industry is a positive, "although the overall market in the US seems to be plateauing".

Earlier Tuesday the top executive at rolled-aluminium product maker Novelis told Reuters that aluminium demand should grow 4 per cent to 5 per cent in 2017, boosted by sales to auto makers.

New York-based Alcoa reported a third-quarter net profit of $US166 million, or 33 cents per share, up from $US44 million, or 6 cents a year earlier. Excluding items, earned 32 cents a share. Analysts, on average, expected 35 cents.

In the most recent quarter, Alcoa reported "productivity gains" of $US377 million across all segments.

Revenue fell to $US5.2 billion from $US5.6 billion a year earlier and was below estimates of $US5.3 billion.

Alcoa shares tumbled $US3.60 to $US27.91 in New York.