The purpose of this provision was thus explained in the Court 's opinion : "Section 7 is designed to arrest in its incipiency not only the substantial lessening of competition from the acquisition by one corporation of the whole or any part of the stock of a competing corporation , but also to arrest in their incipiency restraints or monopolies in a relevant market which, as a reasonable probability , appear at the time of suit likely to result from the acquisition by one corporation of all or any part of the stock of any other corporation .