Are there purchasing power restrictions in grey market trading?

Yes. Proceeds from selling grey market shares are temporarily frozen due to order or listing uncertainty and cannot be used to trade other stocks until the listing is either successful or cancelled.

Example:

If you sell shares for HKD 2,000 in the grey market, the HKD 2,000 will be frozen. During this period, you cannot use these funds to buy other stocks, but you may still use them to repurchase the same grey market stock.