This chapter discusses fundamental or structural changes affecting the relationship of participants in a firm, such as charter amendments, mergers, reincorporations, or share issuances, and how corporate law mitigates the opportunism that can accompany such changes. Jurisdictions differ in their assessment of which situations require a statutory protection mechanism, and the legal strategies to address them. Strategies include: judicial review; double-majority or supermajority requirements; majority-of-the minority requirements; and exit rights. Across all jurisdictions, the law tends to allocate the decision right to the shareholders, thus reversing the board’s power to take independent decisions. Most fundamental changes discussed involve either a management-shareholder conflict or a majority-minority shareholder problem. For charter amendments, most jurisdictions provide for an ex post decision right strategy to ratify the amendment, although there are differences across jurisdictions, taking into account shareholder structure and prevailing agency conflicts. The issuance of new shares can be seen as a course of action that may dilute minority shareholders’ stake; this is frequently addressed by preemptive rights.