A special clause located within a firm's corporate charter that acts as a deterrence against the board of directors passing a share buyback. Taobiz explains Anti-Greenmail Provision This provision acts as a preventative measure, restraining managers from buying back company stock at significant premiums due to greenmail. A majority shareholder may be able to influence the board into purchasing shares at a significant premium, so the anti-greenmail provision requires that a majority of shareholders (excluding the majority shareholder) agree to the buyback.