This section shall not apply to corporations purchasing such stock solely for investment and not using the same by voting or otherwise to bring about, or in attempting to bring about, the substantial lessening of competition ``.

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. The section is violated whether or not actual restraints or monopolies, or the substantial lessening of competition, have occurred or are intended.'' 353 U. S., at 589.

Thus, a finding of conspiracy to restrain trade or attempt to monopolize was excluded from the Court's decision. Indeed, as already noted, the Court proceeded on the assumption that the executives involved in the dealings between du Pont and General Motors acted ``honorably and fairly'' and exercised their business judgment only to serve what they deemed the best interests of their own companies. This, however, did not bar finding that du Pont had become pre-eminent as a supplier of automotive fabrics and finishes to General Motors; that these products constituted a ``line of commerce'' within the meaning of the Clayton Act; that General Motors' share of the market for these products was substantial; and that competition for this share of the market was endangered by the financial relationship between the two concerns: ``The statutory policy of fostering free competition is obviously furthered when no supplier has an advantage over his competitors from an acquisition of his customer's stock likely to have the effects condemned by the statute. We repeat, that the test of a violation of 7 is whether, at the time of suit, there is a reasonable probability that the acquisition is likely to result in the condemned restraints. The conclusion upon this record is inescapable that such likelihood was proved as to this acquisition.'' 353 U. S., at 607.