Australia’s rollercoaster share market has plunged more than four per cent amid a raft of profit warnings, an unprecedented travel ban and cancelled flights.

The benchmark S&P/ASX200 was down 174.7 points, or 3.3 per cent, at 5118.7 at 1030 AEDT as all indices tumbled.

Twenty minutes later it was 3.8 per cent lower.

The broader All Ordinaries index was 171.7 points lower, or 3.32 per cent, at 5161.1 despite a big surge on Wall Street overnight on a big stimulus plan.

By 1050 AEDT, it was 3.78 per cent down.

Local investors have been waiting to hear about Australian measures to ease economic pain from the coronavirus.

Prime Minister Scott Morrison has told Australians not to travel abroad and flagged further measures to stimulate the economy, without detailing them.

However Australia’s ailing airlines will be handed a $715 million federal government lifeline to help the sector through the coronavirus pandemic.

Regional carrier Rex has been urging government action, warning it could go under unless given help during the tumultuous period.

Its shares nosedived almost 10 per cent to 75 cents after half an hour of trading.

Virgin shares rose 11 per cent to seven cents after it cancelled all international flights and slashed domestic capacity.

Qantas shares fell 15.73 per cent at $2.41.

Property developer Mirvac joined the string of listed companies scrapping earnings guidance due to the Covid-19 pandemic on Wednesday.

Mirvac shares fell 4.1 per cent to $2.34.

Ardent Leisure was down more than 15 per cent at 19 cent as the tourism industry is hammered by the coronavirus.

Oil prices sank lower overnight amid an oil price war and recession fears. Woodside fell 4.02 per cent to $18.14 as Santos dipped 8.12 per cent to $3.28 and the wider energy index fell 5.88 per cent.

Gold prices rose overnight as bargain hunters bought up safe haven assets.

Newcrest was up 86 cents, or 3.58 per cent, at $24.86 and Evolution Mining was up 17 cents, or 4.68 per cent, at $3.80.

The “big four” banks dived between 3.8 per cent and 5.16 per cent.

Macquarie Group fell by $6.66, or 6.37 per cent, to $97.83.

On Wednesday data will be released giving a preliminary estimate for Australian retail turnover for February.

The Reserve Bank of Australia is expected to take further measures to protect the economy on Thursday.

The highly volatile local market had its best day ever on Tuesday, gaining 5.8 per cent, after its worst day ever on Monday, falling 9.7 per cent.

Meanwhile, the Aussie dollar has dropped below 60 US cents for the first time since April 2003.

It was buying 59.85 US cents at 1030 AEDT on Wednesday from 60.86 US cents as the market closed on Tuesday.