Hong Kong is tightening oversight of mainland-linked investment accounts across banks and brokerage platforms. The Hong Kong Monetary Authority has required banks to review mainland-opened investment accounts, close accounts opened with suspicious or forged documents, remove inactive zero-balance accounts by May 22, 2026, and obtain written declarations that investment funds come from lawful sources outside mainland China. New details indicate that starting May 26, some Hong Kong banks tightened investment account openings by requiring customers to sign paper declarations, while savings account openings were not affected. Earlier reporting also said some banks required in-person cross-border disclosure statements, asked clients about source of funds and trading records, and in some cases declined to activate investment account functions while banks and brokers reviewed existing accounts.