Stock broker obligations require documented surveillance, internal controls, proprietary account safeguards, mule account detection and employee reporting mechanisms. Regulation 23 requires stock brokers to maintain documented policies and procedures for surveillance systems and internal controls, define governance roles and corrective actions, and review systems at least annually. Brokers must set documented alert thresholds with rationale, ensure proprietary accounts are used only for proprietary trading, restrict trading terminal use to authorised personnel at exchange approved locations, establish processes to detect mule accounts, and provide a mechanism for employees to promptly report suspected fraud or market abuse to senior management.