delivered the opinion of the Court.
This is a civil antitrust action charging a price-fixing agreement in violation of § 1 of the Sherman Act.1 26 Stat. 209, as amended, 15 U. S. C. § 1. The District Court dismissed the complaint. 273 F. Supp. 18. The case is here on appeal, 15 U. S. C. § 29; and we noted probable jurisdiction. 390 U. S. 1022.
The case as proved is unlike any other price decisions we have rendered. There was here an exchange of price information but no agreement to adhere to a price schedule as in Sugar Institute v. United States, 297 U. S. 553, or United States v. Socony-Vacuum Oil Co., 310 U. S. 150. There was here an exchange of information concerning specific sales to identified customers, not a statistical report on the average cost to all members, *335without identifying the parties to specific transactions, as in Maple Flooring Mfrs. Assn. v. United States, 268 U. S. 563. While there was present here, as in Cement Mfrs. Protective Assn. v. United States, 268 U. S. 588, an exchange of prices to specific customers, there was absent the controlling circumstance, viz., that cement manufacturers, to protect themselves from delivering to contractors more cement than was needed for a specific job and thus receiving a lower price, exchanged price information as a means of protecting their legal rights from fraudulent inducements to deliver more cement than needed for a specific job.
Here all that was present was a request by each defendant of its competitor for information as to the most recent price charged or quoted, whenever it needed such information and whenever it was not available from another source. Each defendant on receiving that request usually furnished the data with the expectation that it would be furnished reciprocal information when it wanted it.2 That concerted action is of course sufficient to establish the combination or conspiracy, the initial ingredient of a violation of § 1 of the Sherman Act.
There was of course freedom to withdraw from the agreement. But the fact remains that when a defendant requested and received price information, it was affirming its willingness to furnish such information in return.
There was to be sure an infrequency and irregularity of price exchanges between the defendants; and often the data were available from the records of the defendants or from the customers themselves. Yet the essence of the agreement was to furnish price information whenever requested.
*336Moreover, although the most recent price charged or quoted was sometimes fragmentary, each defendant had the manuals with which it could compute the price charged by a competitor on a specific order to a specific customer.
Further, the price quoted was the current price which a customer would need to pay in order to obtain products from the defendant furnishing the data.
The defendants account for about 90% of the shipment of corrugated containers from plants in the Southeastern United States. While containers vary as to dimensions, weight, color, and so on, they are substantially identical, no matter who produces them, when made to particular specifications. The prices paid depend on price alternatives. Suppliers when seeking new or additional business or keeping old customers, do not exceed a competitor’s price. It is common for purchasers to buy from two or more suppliers concurrently. A defendant supplying a customer with containers would usually quote the same price on additional orders, unless costs had changed. Yet where a competitor was charging a particular price, a defendant would normally quote the same price or even a lower price.
The exchange of price information seemed to have the effect of keeping prices within a fairly narrow ambit. Capacity has exceeded the demand from 1955 to 1963, the period covered by the complaint, and the trend of corrugated container prices has been downward. Yet despite this excess capacity and the downward trend of prices, the industry has expanded in the Southeast from 30 manufacturers with 49 plants to 51 manufacturers with 98 plants. An abundance of raw materials and machinery makes entry into the industry easy with an investment of $50,000 to $75,000.
The result of this reciprocal exchange of prices was to stabilize prices though at a downward level. Knowl*337edge of a competitor’s price usually meant matching that price. The continuation of some price competition is not fatal to the Government’s case. The limitation or reduction of price competition brings the case within the ban, for as we held in United States v. Socony-Vacuum Oil Co., supra, at 224, n. 59, interference with the setting of price by free market forces is unlawful per se. Price information exchanged in some markets may have no effect on a truly competitive price. But the corrugated container industry is dominated by relatively few sellers. The product is fungible and the competition for sales is price. The demand is inelastic, as buyers place orders only for immediate, short-run needs. The exchange of price data tends toward price uniformity. For a lower price does not mean a larger share of the available business but a sharing of the existing business at a lower return. Stabilizing prices as well as raising them is within the ban of § 1 of the Sherman Act. As we said in United States v. Socony-Vacuum Oil Co., supra, at 223, “in terms of market operations stabilization is but one form of manipulation.” The inferences are irresistible that the exchange of price information has had an anticompetitive effect in the industry, chilling the vigor of price competition. The agreement in the present case, though somewhat casual, is analogous to those in American Column & Lumber Co. v. United States, 257 U. S. 377, and United States v. American Linseed Oil Co., 262 U. S. 371.3
*338Price is too critical, too sensitive a control to allow it to be used even in an informal manner to restrain competition.4
Reversed.
Section 1 provides:
“Every contract, combination in the form of trust or otherwise, or conspiracy, in restraint of trade or commerce among the several States, or with foreign nations, is hereby declared to be illegal.”
This is obviously quite different from the parallel business behavior condoned in Theatre Enterprises, Inc. v. Paramount Film Distributing Corp., 346 U. S. 537.
The American Column case was a sophisticated and well-supervised plan for the exchange of price information between competitors with the idea of keeping prices reasonably stable and of putting an end to cutthroat competition. There were no sanctions except financial interest and business honor. But the purpose of the plan being to increase prices, it was held to fall within the ban of the Sherman Act.
Another elaborate plan for the exchange of price data among competitors was involved in American Linseed Oil; and informal *338sanctions were used to establish "modem co-operative business methods.” The arrangement was declared illegal because its “necessary tendency” was to suppress competition. 262 U. S., at 389.
Thorstein Veblen in The Theory of Business Enterprise (1904) makes clear how the overabundance of a commodity creates a business appetite to regulate or control prices or output or both. Measures short of monopoly may have “a salutary effect,” as for example a degree of control or supervision over prices not obtainable while the parties “stood on their old footing of severalty.” But that relief is apt to be “only transient,” for as the costs of production decline and growth of the industry “catches up with the gain in economy,” the need for further controls or restraints increases. And so the restless, never-ending search for price control and other types of restraint.
We held in United States v. Socony-Vacuum Oil Co., 310 U. S. 150, that all forms of price-fixing are per se violations of the Sherman Act.
“The elimination of so-called competitive evils is no legal justification for such buying programs. The elimination of such conditions was sought primarily for its effect on the price structures. Fairer competitive prices, it is claimed, resulted when distress gasoline was removed from the market. But such defense is typical of the protestations usually made in price-fixing cases. Ruinous competition, financial disaster, evils of price cutting and the like appear throughout our history as ostensible justifications for price-fixing. If the so-called competitive abuses were to be appraised here, the reasonableness of prices would necessarily become an issue in every price-fixing case. In that event the Sherman Act would soon be emasculated; its philosophy would be supplanted by one which is wholly alien to a system of free competition; it would not be the charter of freedom which its framers intended.” 310 U. S., at 220-221.