The move has put a brake on a massive spending spree in Hong Kong by mainland traders looking to take advantage of relatively cheap shares in the city.
But Axi strategist Stephen Innes said vast financial support from the Fed, government spending and the vaccine rollout "still points to gleaming days ahead".
Tech giants Alibaba and Tencent surged in Hong Kong after a report that the US will not bar Americans from investing in them, as it has done for other firms over national security concerns.
Bitcoin was sitting at $32,400 after seeing recent wild swings, that saw it hit a record near $35,000 before diving to $28,000 within the space of a day.