A large amount of money that is usually stipulated in a takeover agreement to be paid by a company to its investment banker if another company succeeds to take over the target company. This fee is meant to foil attempts by other companies to make bids for the target, lest they would end up paying the backup fee if successful in their bid. In other words, the large amount would be paid if a takeover deal is not completed because a target company walks away from the transaction after the agreement is signed.