Theory predicts that capping brokers’ compensation exacerbates the exploitation of retail investors. We show that regulated caps on mutual fund 12b-1 fees, effectively sales commissions, are associated with negative equity fund performance, but only after a structural shift toward maximum permitted levels of the fees around 2000. Past this break point, flow–performance sensitivity shifts from the middle- to the highest-performing funds, suggesting that the fee cap increases performance-chasing behavior by constraining brokers’ incentives to learn about lower-ranked funds. The policy implication is that regulators must reevaluate the efficacy of caps on brokerage fees.