Hong Kong stocks tumbled Wednesday as Asian markets retreated on recession fears and traders re-evaluated their recent big bets on China's reopening, even as mainland officials unveiled fresh measures to roll back Covid restrictions.

The Hang Seng Index dived 3.22 percent, or 626.36 points, to close at 18,814.82.

The Shanghai Composite Index fell 0.40 percent, or 12.91 points, to 3,199.62, though the Shenzhen Composite Index on China's second exchange edged up 0.15 percent, or 3.11 points, to 2,071.04.

The losses were in line with a retreat across Asia and followed a second successive day of selling on Wall Street after heads of top banks including JP Morgan and Goldman Sachs warned of a dour outlook for the US economy and possible recession.

The comments came as traders were already spooked by forecast-beating reports on jobs and the giant US services sector, which fanned worries the Federal Reserve will have to push interest rates higher than hoped.

The bleak mood overshadowed China's moves to wind back some of its harsh Covid rules that traders hope will kickstart the world's number two economy.

On Wednesday officials announced for the first time a nationwide loosening of restrictions, including a reduction in mandatory PCR tests and allowing some positive cases to quarantine at home.

But in a sign of the impact the zero-Covid strategy has had, data Wednesday also showed that imports and exports and imports plunged far more than expected in November.

Observers also said the recent rally fuelled by the reopening may have gone too far and traders were now taking a step back as they contemplate a likely spike in infections in the country as it opens up.

Losses were across the board in Hong Kong, with tech firms, property developers and Macau casinos -- which have all rallied recently on the easing measures -- well down.