This research employs a difference-in-differences framework to study the impact of major board reforms on the performance of mergers and acquisitions (M&As). Using an international sample of board reforms implemented in 61 countries from 1985 to 2021, we document a drastic redistribution of wealth from target shareholders to acquirer shareholders after the board reforms in target countries. This effect is most pronounced in M&A transactions that involve the sale of controlling shares, thereby supporting the hypothesis that corporate board reforms mitigate the private benefits of control in the target firm. Furthermore, these reforms increase expected deal synergies, in that deal-level announcement returns are higher after the implementation of the reforms. When country-level institutional quality and legal protection of shareholders are greater, it reinforces the reform effects. Overall M&A activity remains unchanged following the reforms, yet financial bidders complete fewer transactions, implying a reform-induced squeeze-out of financial bidders from the M&A market in the target country. Collectively, these international results are consistent with the predictions of the private benefits of control theory and underscore the role of institutional quality and investor protection in reinforcing the effects of board reforms worldwide.