More than $11 trillion is invested in mutual funds in the United States. Mutual fund investors flock to funds with high past returns, despite there being little, if any, relationship between high past returns and high future returns. Because fund management fees are based on the amount of assets invested in their funds, however, fund companies regularly advertise the returns of their high-performing funds. The SEC requires these advertisements to contain a disclaimer warning that past returns do not guarantee future returns and that investors could lose money in the funds. This article presents the results of an experiment that finds that this SEC-mandated disclaimer is completely ineffective. The disclaimer neither reduces investors' propensity to invest in advertised funds nor diminishes their expectations regarding the funds' future returns. The experiment also suggests, however, that a stronger disclaimer—one that informs investors that high fund returns generally do not persist—would be much more effective.