The Australian share market was weaker by early afternoon after a negative lead from Wall Street, while the resources sector rallied.

The benchmark S&P/ASX 200 index plunged 19.6 points, or 0.43 per cent, at 4510.3, while the broader All Ordinaries index fell to 4522.3, a decline of 19.8 points 0.44 per cent.

On the Sydney Futures Exchange, the September share price index contract dived 24 points at 4484, on 9890 contracts.

Burrell Stockbroking adviser Daniel Manley said the Australian bourse was due to set back after its recent rally. "I think the market has had a good run, so this was going to happen at some point," he said.

"We had to have a down day, so the first sign of any pullback in the US and our market related with that.

"The market is well and truly stuck with this trend that we've been seeing over the past couple of weeks.

"It's really waiting for two things to pass, reporting season and the election - so until those things are out of the way, I don't think we'll see the market with any urge to go one way or the other.

"We'll probably follow the US to some extent, but certainly with no conviction."

The buoyant resources sector was sustaining the market.

Mining stocks had gained across the board, with major player BHP Billiton climbing 15 cents at $40.35 and Rio Tinto adding 6c at $71.10.

Gold producer Newcrest Mining rose 14c at $32.92 and so did its takeover target Lihir Gold, which ascended 2c at $4.08.

The finance sector, however, took losses. Commonwealth Bank dropped 19c at $52.41, while Westpac slumped 24c to $23.91. NAB lost 17c to $25.17 and ANZ went down 23c to $23.00.