This study examines whether requiring the disclosure of audited financial statements disciplines managers' mergers and acquisitions (M&As) decisions. When an M&A transaction meets certain disclosure thresholds, the Securities * University of Illinois at Urbana-Champaign.Accepted by Douglas Skinner. This paper is based on my dissertation completed at the University of Iowa. I am indebted to my dissertation cochairs Dan Collins and Rick Mergenthaler for their invaluable guidance and support. I thank my dissertation committee members Paul Hribar, Dave Mauer, and Anand Vijh for their helpful feedback. I also received constructive comments and suggestions from and Exchange Commission (SEC) requires the public acquirer to disclose the target's audited financial statements after the merger is completed. Using hand-collected data, I find that the disclosure of private targets' financial statements is associated with better acquisition decisions. Furthermore, I find that this disciplining effect of disclosure is more pronounced when monitoring by outside capital providers is more difficult and costly, and when other disciplining mechanisms are weaker. Finally, these findings are robust to several alternative explanations, such as monitoring from blockholders and voluntary disclosures. In sum, the evidence suggests that the ex post mandatory disclosure of private targets' accounting information disciplines managers' acquisition decisions and improves acquisition efficiency. JEL codes: G34; M40; M41; M48