Some Hong Kong licensed banks, including HSBC Hong Kong and Hong Kong branches of mainland Chinese banks, have begun asking certain existing mainland Chinese investment clients to submit written source-of-funds declarations, with Aug. 20 and Sept. 12 deadlines. Failure to respond could lead first to suspension and later to termination of investment services. The review is based on a May 22 circular issued by the Hong Kong Monetary Authority with the Hong Kong Securities and Futures Commission, rather than a new regulatory policy. It covers zero-balance investment accounts held by mainland investors that had no client-initiated trading activity in the preceding 12 months as of May 22, 2026. Banks must notify affected clients, suspend new transactions unless accounts are reactivated, and close accounts that remain unresolved within six months, or by Nov. 22, 2026, subject to exceptional circumstances. Reactivation requires a written declaration confirming that investment funds originated from legitimate sources outside mainland China, while active accounts are not directly affected in the short term.