Both cash accounts and margin accounts can trade grey market stocks. Margin accounts may use margin financing to purchase grey market stocks. However, grey market stocks themselves cannot be pledged as collateral for margin financing.
Explanation: Difference Between Margin-Eligible Collateral Stocks and Margin-Financed Stocks
Margin-Eligible Collateral Stocks
Margin-Financed Stocks
In summary: Grey market stocks can be purchased using margin financing, but they cannot themselves be used as collateral to generate margin buying power.
EleBank Causeway Bay Physical Store
Address: Shop S & X, Hong Kong Mansion, 1A-1L Yee Wo Street, Causeway Bay (Exit E of Causeway Bay Station)
Opening hours: Monday to Sunday - 10am to 9pm (The Physical Store's opening hours may be adjusted on certain public holidays. Please refer to the Bank's announcements.)