dissenting.
Agreements among competitors1 to divide markets are per se violations of the Sherman Act.2 The most de*178tailed, grandiose scheme of that kind is disclosed in Addyston Pipe & Steel Co. v. United States, 175 U. S. 211, where industrialists, acting like commissars in modern communist countries, determined what tonnage should be produced by each company and what territory was “free” and what was “bonus.” The Court said: “Total suppression of the trade in the commodity is not necessary in order to render the combination one in restraint of trade. It is the effect of the combination in limiting and restricting the right of each of the members to transact business in the ordinary way, as well as its effect upon the volume or extent of the dealing in the commodity, that is regarded.” Id., at 244-245.
In United States v. National Lead Co., 332 U. S. 319,3 a Sherman Act violation resulted from a division of world markets for titanium pigments, the key being allocation of territories through patent license agreements. A similar arrangement was struck down in Timken Co. v. United States, 341 U. S. 593, where world trade territories were allocated among an American, a British, and a French company through intercorporate arrangements called a “joint venture.” Nationwide Trailer Rental System, Inc., v. United States, 355 U. S. 10 (affirming 156 F. Supp. 800), held violative of the antitrust laws an agreement establishing exclusive territories for each member of an organization set up to regulate the one-way trailer rental industry and empowering a member to prevent any other operator from becoming a member in his area.
In the late 1950’s the only producers of sodium chlorate in the United States were Pennsalt, one of the appellees *179in this case, Hooker Chemical Corporation, and American Potash and Chemical Corporation. No new firms had entered the industry for a decade. Prices seemed to be stable and little effort had been made to expand existing uses or to develop new ones. But during the 1950’s the sodium chlorate market began to grow, chiefly on account of the adoption of chlorine dioxide bleaching in the pulp industry. Domestic production more than quadrupled between 1950 and 1960. The growth was the most pronounced in the southeast. By 1960 the southeast had the heaviest concentration of sodium chlorate buyers, the largest being the pulp and paper mills; and nearly half the national sodium chlorate productive capacity. In 1960 the southeast market was divided among the three producers as follows: Hooker, 49.5%, American Potash, 41.6%, Pennsalt, 8.9%
Pennsalt, whose only sodium chlorate plant was at Portland, Oregon, became interested in establishing a plant in the rapidly growing southeast sodium chlorate market. It made cost studies as early as 1951 for such a project; and from 1955 on it gave the matter almost continuous consideration. In 1957 it decided to explore the possibility either of going it alone or doing it jointly with Olin. Pennsalt received from its staff and experts various studies in this regard and continued to have negotiations with Olin for a joint venture, and postponed its unilateral project from time to time pending receipt of word from Olin. Its final decision was in fact made when Penn-Olin was organized February 25, 1960, pursuant to a joint venture agreement between Olin and Pennsalt, dated two weeks earlier.
In the early 1950’s Olin too was investigating the possibilities of entering the southeast industry. It took various steps looking toward establishment of a production plant in the southeastern United States. It received numerous reports from its staff and its experts and it went *180so far in November 1959 as to reach a tentative agreement with a British construction company for the construction of a plant. Its unilateral projects were, however, all dropped when the agreement for the joint venture with Pennsalt was reached.
During the years when Pennsalt and Olin were considering independent entry into the southeast market, they were also discussing joint entry. In order to test the southeast market the two agreed in December of 1957 that Pennsalt would make available to Olin, as exclusive seller, 2,000 tons of sodium chlorate per year for two or three years, Olin agreeing to sell the chemical only to pulp and paper companies in the southeast, except for one company which Pennsalt reserved the right to serve directly. Another agreement entered into in February 1958 provided that neither of the two companies would “move in the chlorate or perchlorate field without keeping the other party informed.” And each by the agreement bound itself “to bring to the attention of the other any unusual aspects of this business which might make it desirable to proceed further with production plans.” The purpose of this latter agreement, it was found, was to assure that each party would advise the other of any plans independently to enter the market before it would take any definite action on its own.
So what we have in substance is two major companies who on the eve of competitive projects in the southeastern market join forces. In principle the case is no different from one where Pennsalt and Olin decide to divide the southeastern market as was done in Addyston Pipe and in the other division-of-markets cases already summarized. Through the “joint venture” they do indeed divide it fifty-fifty. That division through the device of the “joint venture” is as plain and precise as though made in more formal agreements. As we saw in the Timken case, *181“agreements between legally separate persons and companies to suppress competition among themselves and others” cannot be justified “by labeling the project a ‘joint venture.’ ” 341 U. S., at 598. And we added, “Perhaps every agreement and combination to restrain trade could be so labeled.” Ibid. What may not be done by two companies who decide to divide a market surely cannot be done by the convenient creation of a legal umbrella — whether joint venture or common ownership and control (see Kiefer-Stewart Co. v. Seagram & Sons, 340 U. S. 211, 215) — under which they achieve the same objective by moving in unison.
An actual division of the market through the device of “joint venture” has, I think, the effect “substantially to lessen competition” within the meaning of § 7 of the Clayton Act.4 The District Court found that neither Pennsalt nor Olin had completely rejected the idea of independent entry into the southeast. But the court also found that it is “impossible to conclude that as a matter of reasonable probability both Pennsalt and Olin would have built plants in the southeast if Penn-Olin had not been created.” The only hypothesis acceptable to it was that either Pennsalt or Olin — but not both — would have entered the southeastern market as an independent competitor had the “joint venture” not materialized. On that assumption the only effect of the “joint venture” was *182“to eliminate Pennsalt or Olin, as the case may be, as a competitor.” In that posture of the case, the District Court was unwilling to conclude that the creation of Penn-Olin had the effect of substantially lessening competition.
We do not, of course, know for certain what would have happened if the “joint venture” had not materialized. But we do know that § 7 deals only with probabilities, not certainties. We know that the interest of each company in the project was lively, that one if not both of them would probably have entered that market, and that even if only one had entered at the beginning the presence of the other on the periphery would in all likelihood have been a potent competitive factor. Cf. United States v. El Paso Natural Gas Co., 376 U. S. 651, 661. We also know that as between Pennsalt and Olin the “joint venture” foreclosed all future competition by dividing the market fifty-fifty. That could not have been done consistently with our decisions had the “joint venture” been created after Pennsalt and Olin had entered the market or after either had done so. To allow the joint venture to obtain antitrust immunity because it was launched at the very threshold of the entry of two potential competitors into a territory is to let § 7 be avoided by sophisticated devices.
There is no need to remand this case for a finding “as to the reasonable probability that either one of the corporations would have entered the market by building a plant, while the other would have remained a significant potential competitor.” Ante, pp. 175-176. This case — now almost three years in litigation — has already produced a trial extending over a 23-day period, the introduction of approximately 450 exhibits, and a 1,600-page record. We should not require the investment of additional time, money, and effort where, as here, a case turns on one cru*183cial finding and the record is sufficient to enable this Court — -which is as competent in this regard as the District Court — to supply it.
Mr. Justice Harlan,dissenting.
I can see no purpose to be served by this remand except to give the Government an opportunity to retrieve an antitrust case which it has lost, and properly so. Believing that this Court should not lend itself to such a course, I would affirm the judgment of the District Court.
White Motor Co. v. United States, 372 U. S. 253, was a vertical arrangement involving a territorial restriction whose validity we con-*178eluded could be determined only after a trial, not on motion for summary judgment.
See Oppenheim, Antitrust Booms and Boomerangs, 59 Nw. U. L. Rev. 33, 35 (1964).
The findings of fact are detailed in 63 F. Supp. 513.
Section 7 of the Clayton Act covers the acquisition by a corporation engaged in interstate commerce of the stock or assets of another corporation also engaged in interstate commerce. An acquisition qualifies under § 7 if the firm that is acquired is either conducting business in interstate commerce or intending or preparing to do so. It seems clear from the record in this case that Penn-Olin was from its inception intended by its organizers to engage in interstate commerce; and it in fact immediately began to arrange for or conduct such business. It was therefore “engaged” in interstate commerce within the meaning of § 7 when Pennsalt and Olin acquired its stock.