Generally a merger marries resources of the two previous companies and the "people talent" as well. Most mgts. have studied the other company and know full-well it will be a good combination of things and personnel, or else they break it off and decide differently. And they have a pretty good idea HOW they will align divisions, departments and even after-management of the 'future company.' And, of course who the CEO is going to be. All this kind of "stuff" is put together prior to the completion of the merger!
A merger is an agreement between two existing companies to unite into a single company as part of strategic effort to boost shareholder value . When the merger takes place the pps spikes Booom!!! Booommm!! .. When that is going to happen God knows.