“Best execution” is among the more quixotic duties in the canon of investor protection. As agent, a broker owes its principal a duty “to execute promptly,” “to execute in an appropriate market,” and “to obtain the best price.”1 In today’s market, the quality of retail executions is perhaps better than it has ever been: technological advances and the dismantling of barriers to competition have whittled at commissions and narrowed trading spreads.2 And yet with each controversy – such the recent GameStop affair – Congress and the Securities and Exchange Commission (SEC) inexorably air their concerns that brokers and dealers skim undeserved profits or shirk execution obligations when handling retail transactions.3