Ex-ante means “before the fact”; ex-post means “after the fact.” To the extent that the original ownerentrepreneur can set up a situation (charter) that encourages best (i.e., from the perspective of the firm)

ex-post behavior, the ex-ante value (for which the firm can be sold right now) is maximized. However, if the situation (charter) is such that the owner himself or his managers will later try to expropriate capital providers, or such that the managers will make bad decisions in the future, then the ex-ante value today for which the firm can be sold would be less.