Qualified stock broker designation requires enhanced governance, risk management, cybersecurity and investor complaint mechanisms. Regulation 18D authorizes designation of qualified stock brokers based on parameters including active client count, clients' total assets, trading and proprietary volumes, end of day margin obligations, and specified compliance and grievance scores; designated brokers must maintain appropriate governance, risk management, scalable infrastructure, an orderly winding down framework, robust cyber security, and investor services including online complaint redressal.