According to the Model Code for Securities Transactions by Directors of Listed Issuers in Hong Kong Listing Rules, what must a listed issuer do before a blackout period begins?
ID : 1902
Long answer : Issuers must inform HKEX before imposing trading restrictions. (Source: https://en-rules.hkex.com.hk/sites/default/files/net_file_store/HKEX4476_3785_VER31169.pdf)