We examine a regulatory change that increased the reporting frequency of mutual funds' portfolios. Using a difference‐in‐differences design, we find that firms with greater ownership by mutual funds increase share repurchases following the regulatory change. We show that these share repurchases are a firm's rational response to undervaluation, which occurs because fund managers become shortsighted following the regulation and sell companies with good long‐term prospects. Collectively, our results shed light on an unintended consequence of more frequent reporting in a delegated asset management framework.