The system was designed to criminalize any attempt to monopolize, not just block the transaction.
The Sherman antitrust act was quite clear about it:
> Sec. 2. Every person who shall monopolize, or attempt to monopolize, or combine or conspire with any other person or persons, to monopolize any part of the trade or commerce among the several States, or with foreign nations, shall be deemed guilty of a misdemeanor, and, on conviction thereof; shall be punished by fine not exceeding five thousand dollars, or by imprisonment not exceeding one year, or by both said punishments, in the discretion of the court.
Later it was made a felony.
It is not enforced this way by the courts.