Myopic loss aversion (MLA)—the tendency to avoid risk when investment outcomes are evaluated frequently—has long been cited as a key behavioral explanation for overly conservative portfolios. However, importantly it has remained unclear whether MLA is primarily driven by the frequency of performance feedback or by the flexibility to revise investment decisions (i.e., the decision frequency). Previous studies have yielded mixed evidence. To address this, we conducted two studies; each independently manipulating feedback and decision frequency, featuring substantially higher statistical power than previous research. Our results indicate that MLA is driven by decision rather than feedback frequency. These results refine the theoretical foundations of MLA, with implications for the design of investment interfaces, behavioral finance, and policy interventions aimed at improving long-term investment outcomes.