Investment advisers and broker-dealers have a fiduciary duty to seek best execution of trades for their respective clients. In the wake of the recent “meme stock” phenomenon, which was driven in part by commission-free trading and the associated payment for order flow, FINRA has issued a regulatory notice reminding member firms of the regulatory requirements concerning best execution and payment for order flow. This article discusses the key takeaways from the notice, with commentary from Carlo di Florio, chief services officer at ACA Group and former Chief Risk and Strategy Officer at FINRA, and Susan Schroeder, partner at WilmerHale and former Executive Vice President of Enforcement at FINRA. For more on meme stocks, see “GameStop and the Challenges of Monitoring Communication Channels” (May 13, 2021).