After sinking below 5,000 for the first time since 2016, the benchmark S&P/ASX200 gained 655 points in the final three and a half hours of trade to finish Friday 234.7 points higher at 5,539.3.

The broader All Ordinaries index closed up 219.8, or 4.09 per cent, to 5,590.7.

There was no single reason for the "massive" rebound, said CommSec analyst James Tao.

"I wouldn't necessarily pinpoint it to any one catalyst," he said. "There's a combination of factors."

Prime Minister Scott Morrison fronted the media with Chief Medical Officer Brendan Murphy as the market rebounded.

In the United States, US House Speaker Nancy Pelosi told reporters that House Democrats and the White House were close to agreeing on a fiscal stimulus package.

US stocks futures turned around, going from indicating a 70 0 point loss for the Dow to pointing to a 500-point gain.

And earlier in the day, the Federal Reserve took steps to inject an unusually large amount of cash into the US financial system to preserve liquidity.

Other Asian markets were down and across the Tasman, the NZX 50 finished 4.9 per cent lower.

The ASX's turnaround overshadowed the continued drop in the Australian dollar, which sunk below 63 US cents for the first time since 2003.

Since the start of the year it has lost over 10 per cent of its value, going from 70.16 cents at the end of 2019 to trading at just 62.98 US cents at 1719 AEDT on Friday.

Even with the gains the ASX finished the week down down 10.9 per cent, or 676.9 points, and has lost 23 per cent of its value since hitting a record high on February 20.

Healthcare shares were the biggest beneficiary of the late rally, collectively climbing 10.6 per cent as CSL jumped 11.9 per cent to $313.83 and Cochlear rose 21.1 per cent to $216.11.

Consumer shares gained an average of around six per cent, with Coles gaining 8.7 per cent to $16.05, Woolworths rising 6.7 per cent to $37.05 and Wesfarmers climbing 8.0 per cent to $37.85.

The energy sector rose 8.3 per cent, with Oil Search climbing 17.2 per cent to $3.48 and Woodside Petroleum up 9.9 per cent to $20.97.

The battered banking sector was up 3.7 per cent, with Commonwealth up 5.2 per cent to $66.36, ANZ up 3.0 per cent to $18.80, NAB up 1.5 per cent to $18.41 and Westpac up 2.1 per cent to $18.12.

Telstra rose 6.4 per cent to $3.32.

In the mining sector, BHP gained 1.5 per cent to $26.72, Rio Tinto rose 4.8 per cent to $81.08 and Fortescue Metals rose 13.0 per cent to $9.93.

Goldminers were mostly lower as the price of the precious metal dropped as low as $US1,555, its lowest level since the coronavirus outbreak began, before rebounding somewhat.

Northern Star fell 8.1 per cent and Evolution dropped 3.1 per cent, although Newcrest rose 2.9 per cent.

Every sector rose except for utilities and property trusts, which were down 0.6 and 0.9 per cent, respectively.

Travel stocks also did not benefit, with Qantas declining 12.6 per cent to a more than three-year low of $3.18 and Flight Centre dipping 2.4 per cent to $19.15 after announcing it would close up to 100 stores.

Mr Tao said it was hard to say whether the market had finally hit bottom and how things went from here would depend on the course of the outbreak.

"It doesn't mean we're out of the woods by any means," he said.

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Australian Associated Press