The Australian share market has dropped at the open with losses across the board, reflecting concerns US politicians will be unable to reach a deal to avoid a default.

With the US government shutdown about to enter its 14th day, US Senate Majority Leader Harry Reid said he had a "productive conversation" with his Republican counterpart Mitch McConnell.

Mr Reid said talks would continue and he was "optimistic about the prospects for a positive conclusion".

But investors appear unnerved by the continued deadlock, as the deadline to raise the country's borrowing authority looms at the end of the week.

At 11am (AEDT) the benchmark ASX 200 index had lost 0.4 per cent or 21 points to 5,209 and the broader All Ordinaries Index was down 20 points at 5,209.

The largest losses were among technology and energy shares; Whitehaven Coal has lost 2.1 per cent and the oil and gas producer Santos was 1.8 per cent lower.

Shares in the insurance comparison website iSelect added 3.2 per cent to $1.30 after its chief executive Matt McCann resigned just four months after the company listed on the share market.

Mr McCann announced he would step down immediately, at the same time as the company warned it would fail to meet its revenue forecasts this financial year.

Mining stocks were also out of favour, with iron ore miner Fortescue Metals down 0.8 per cent, while diversified miner BHP Billiton was down 0.2 per cent and its main rival Rio Tinto 0.3 per cent lower.

Copper and gold miner Oz Minerals has shed 7.3 per cent while Australia's largest gold miner Newcrest was down another 3.8 per cent after the spot price of gold fell to a three-month low of $US1271 an ounce.

The dollar was slipping against the greenback, fetching 94.4 US cents.