When issuers need to reference the closing price of overseas underlying stocks on the last-cum date to make corporate action adjustment to the CBBCs, due to the time difference between Hong Kong and the location of overseas exchange (for example the US), issuers may not be able to announce the adjustments before trading of related CBBCs commences on the Exchange on the Exchange’s trading day immediately following close of trading on the overseas exchange on the last-cum date. Given the adjusted terms have not been announced, trading in those CBBCs will be suspended for that entire trading day of the Exchange.
You should note that depending on the type of corporate action, trading in the CBBCs on the Exchange may be suspended for more than one trading day in certain circumstances. In all cases, issuers will publish announcements setting out the corporate action adjustment and suspension arrangement (if any), you can refer to HKEXnews website for details.