We study the "dark" role of advisory banks in the market for corporate control. We argue that advisors are privy to information about the deal that they may directly exploit by investing in the target firm. We show that the advisors to the bidders often have positions in the target before the deal announcement and that profit from such a position. A trading strategy conditional on the advisor's stake delivers a net-of-risk performance of 4.08% per month. This cannot be replicated using publicly available information. Advisors not only take positions in the deals on which they advise, but also directly affect the outcome of the deals, negotiating conditions that increase the probability of success. This has negative implications for the viability of the new entities.