A study reported in the Blog of Corporate Governance concludes that the market ultimately rewards the share price of corporations that adopt policies of good corporate governance:
Both managements and investors should take market learning into account, paying close attention to the potential increase in market capitalization that eliminating anti-takeover provisions could produce. Many firms have already eliminated anti-takeover provisions in recent years, removing staggered boards and supermajority requirements for mergers. Lowering entrenchment levels, rather than trading on them, continues to offer opportunities for substantial returns to firms’ shareholders.
Furthermore, while markets now price anti-takeover provisions, our findings raise the possibility that markets do not (yet) price other governance features whose emergence is relatively more recent. The introduction of new governance arrangements and their subsequent incorporation into prices is a gradual process, a work constantly in progress.