Using a comprehensive sample of U.S. mutual funds from 1992 to 2004, we find strong evidence that investment bank-affiliated funds underperform unaffiliated funds. Consistent with the conflict of interest hypothesis, we find that affiliated funds hold disproportionately large amounts of stocks of their initial public offering and seasoned equity offering clients. Moreover, worse-performing clients are more likely to be held by affiliated funds. Our results are robust to alternative risk adjustments, portfolio weighting schemes, and regression methodologies. Overall, our findings are consistent with the idea that investment banks use affiliated funds to support underwriting business at the expense of fund shareholders.