NEW YORK (AFP) - Wall Street on Wednesday (Dec 9) continued its pattern of setting records and then retreating, closing lower amid uncertainty over a new US relief package and rising coronavirus cases.

The benchmark Dow Jones Industrial Average sunk 0.3 per cent to finish the day at 30,068.81.

The broad-based S&P 500 fell 0.8 per cent to end at 3,672.82, while the tech-rich Nasdaq Composite Index lost 1.9 per cent to end at 12,338.95, the day after each set new records.

Expectations for the release of a Covid-19 vaccine and the potential Congress would pass a new spending package to support the US economy had boosted investor sentiment in recent days.

But rising coronavirus cases and the continued stalemate among lawmakers sapped some of the good feeling.

Treasury Secretary Steven Mnuchin on Tuesday unveiled a US$916 billion (S$1.2 billion) stimulus spending proposal proposal, however its likelihood of winning over Democrats controling the House of Representatives and Republicans leading the Senate is unclear.

"You have a tug of war between virus news and vaccine news and the tiebreaker has been the potential for a stimulus. When there's any bump in the road, the market deserves a breather and I think that's what happened today," Art Hogan of National Holdings, told AFP.

"That gridlock is certainly enough for us to take a breather," he said of the ongoing stimulus talks.

Bucking the trend, food delivery startup DoorDash surged 86 per cent in its US stock market debut on Wednesday, as frenzied investors pushed the shares up to a whopping US$189.51.

Another tech unicorn, Airbnb, makes its debut on Thursday.

Meanwhile, FireEye was fell 13 percent after the hacker-fighting firm announced Tuesday its owns defenses had been breached by sophisticated attackers who made off tools with used to test customers' computer systems.