Reg BI, short for Regulation Best Interest, is a Securities and Exchange Commission rule that enhances the standards of conduct for broker-dealers and their registered representatives when recommending securities transactions or investment strategies to retail customers. Under Reg BI, brokers must act in the best interest of the retail customer at the time a recommendation is made, without placing their own interests ahead of the customer's. The rule imposes four main obligations: disclosure, care, conflict of interest, and compliance. Reg BI applies to recommendations of variable annuities, registered index-linked annuities, mutual funds, and other securities products commonly used in insurance and retirement planning.

In practice, firms implement Reg BI through updated policies, training, and documentation standards that require advisors to gather detailed client information, consider reasonably available alternatives, and document why a recommendation is in the client's best interest. Point-of-sale forms, customer relationship summaries (Form CRS), and product comparison tools are redesigned with Reg BI in mind. Supervisors review recommendations for high-fee or complex products such as variable annuities and registered index-linked annuities to ensure alignment with the rule. Advisors must understand how Reg BI differs from prior suitability standards and how it interacts with state best-interest rules and DOL exemptions. Using "Reg BI" shorthand in meetings is common, but firms stress that the underlying obligations are substantive, not just paperwork.