MR. JUSTICE STEWART delivered the opinion of the Court.For many years, the State of Georgia restricted banks located in cities from opening branches in suburban areas.  To circumvent these restrictions in the Atlanta area, the Citizens & Southern National Bank (C&S National) formed the Citizens & Southern Holding Company (C&S Holding), and the latter company embarked on a program of forming de facto branch banks in the suburbs of Atlanta.  This program involved, among other features, ownership by C&S Holding of 5 percent of the stock of each of the suburban banks (the maximum allowed by state law), ownership of much of the remaining stock by parties friendly to C&S, [Footnote 1] use by the suburban banks of the C&S logogram and of all of C&S's banking services, and close C&S oversight of the operation and governance of the suburban banks.  The expectation on all sides -- by C&S, by the suburban banks, and by state and federal bank regulators -- was that C&S would acquire these "5-percent banks" outright, and convert them into de jure branches as soon as state law or the Atlanta city limits Page 422 U. S. 90 were altered so as to permit the accomplishment of this end.In 1970, Georgia amended its banking statutes to allow de jure branching on a county-wide basis.  Because the city of Atlanta is contained within two counties, DeKalb and Fulton, which encompass the Atlanta suburbs in which the 5-percent banks operated, this change in the law meant that C&S National could now absorb the 5-percent banks as true branches.  C&S consequently applied to the Federal Deposit Insurance Corporation (FDIC), under the Bank Merger Act of 1966, 80 Stat. 7, 12 U.S.C. § 1828, for permission to acquire all of the stock of six of the 5-percent banks historically operated by C&S as de facto branches.  The FDIC authorized all but one of the proposed acquisitions.The Justice Department immediately commenced this litigation in a Federal District Court for injunctive relief, alleging that the five acquisitions authorized by the FDIC would lessen competition in relevant banking markets, and thus violate § 7 of the Clayton Act, 38 Stat. 731, as amended, 64 Stat. 1125, 15 U.S.C. § 18, and that the historic "de facto branch" relations between C&S and the six 5-percent banks constituted unreasonable restraints of trade in violation of § 1 of the Sherman Act, 26 Stat. 209, as amended, 15 U.S.C. § 1.  After a trial, the court rendered judgment for C&S on all the issues.  372 F. Supp. 616.  The Government appealed under § 2 of the Expediting Act, 32 Stat. 823, as amended, 15 U.S.C. § 29, and we noted probable jurisdiction. [Footnote 2] Page 422 U. S. 91I. The Background of This LitigationIn applying the antitrust laws to banking, careful account must be taken of the pervasive federal and state regulation characteristic of the industry, "particularly the legal restraints on entry unique to this line of commerce."  United States v. Marine Bancorporation, 418 U. S. 602,  418 U. S. 606.  This admonition has special force in the present case, for the de facto branch arrangements and the proposed acquisitions involved here were a direct response to Georgia's historic restrictions on branch banking.Before 1927, Georgia permitted state-wide branching, and C&S National, then as now headquartered in Savannah, established three branches in the city of Atlanta.  In 1927, state law was changed to prohibit all branching. [Footnote 3]  C&S therefore decided to expand through the formation of a bank holding company.  C&S Holding was founded in 1928, and between 1946 and 1954, this company purchased two banks, and founded a third, in the Atlanta area.  But in 1956, Georgia again altered its statutes to prohibit a bank holding company from acquiring more than 15 percent of a bank's stock.  Georgia Bank Holding Company Act, 1 Ga.Laws 1956, pp. 309312.  A 1960 amendment, still in force, reduced the maximum ownership level to 5 percent.  Ga.Code Ann. 13-207(a)(2) (1967 ed. and Supp. 1974).By the 1950's, C&S National was interested primarily in suburban expansion.  The Atlanta city limits had been frozen since 1952, and the area's economic and population growth consequently occurred primarily outside the city's boundaries.  Between 1959 and 1969, C&S Holding accordingly established in the Atlanta suburbs (in DeKalb and Fulton Counties) the six 5-percent Page 422 U. S. 92 banks at issue in this case.  Five of these banks were founded under the sponsorship of C&S; the sixth, the Tucker Bank, had long been an independent suburban bank when, in 1965, C&S converted it into a 5-percent bank. [Footnote 4]Each of these six banks was made a "correspondent associate" bank within the C&S system.  This status involved many different relationships between the 5-percent bank and C&S:  in addition to the 5-percent stock held by C&S Holding, substantial shares were also held by officers, shareholders, and friendly customers of other C&S banks, and by their family members.  It was understood from the outset that the 5-percent banks would be acquired outright by C&S as soon as the law permitted.  From at least 1965 on, the 5-percent banks used the C&S logogram on their buildings, papers, and correspondence.  C&S filed the charter applications of the 5-percent banks Page 422 U. S. 93 and openly assured the banks of full financial support, assurances which were often instrumental in securing regulatory approval of their creation.  C&S chose the principal executive officer for each 5-percent bank.  The employees of these banks were accorded the same pension and promotion rights in the C&S system as possessed by their colleagues at C&S National and its de jure affiliates.  C&S selected the location of, and oversaw the selection of directors for, the suburban banks.  A C&S executive served as an "advisory director" to each suburban bank.  C&S conducted surprise audits and credit checks at the suburban banks.  Each of the suburban banks provided the full panoply of C&S banking services, and customers of any 5-percent bank could avail themselves of these services at any of the other 5-percent banks, or at C&S National and its de jure branches.  C&S supplied to each 5-percent bank, through manuals and memoranda, a large quantity of information concerning every conceivable banking procedure and problem.  Included were data -- stamped "for information only" -- concerning interest rates and service charges employed by C&S National and its de jure branches, but each 5-percent bank was cautioned to use its own judgment in setting interest rates and service charges.  In sum, it is fair to say -- and the parties agree -- that, in almost every respect save corporate form, each of the 5-percent banks was a de facto branch of C&S National.Between 1966 and 1968, the Federal Reserve Board investigated C&S's network of correspondent associate banks.  The purpose of the investigation was to determine whether C&S was exerting such control over the 5-percent banks as to require special "approval" of the Federal Reserve Board pursuant to § 3 of the Bank Holding Company Act of 1956, as amended.  12 U.S.C. § 1842.  The investigation ended in an "understanding" between the Board's staff and C&S that the "correspondent Page 422 U. S. 94 associate" program, as the staff understood it, did not require formal approval. [Footnote 5]  The Justice Department participated in this investigation, and took no action of any kind inconsistent with this "understanding."In 1970, Georgia amended its banking statutes to permit de jure branching within any county in which a bank already had an office.  Ga.Code Ann. 13-203.1(a) (Supp. 1974).  This allowed C&S National to branch into those Atlanta suburbs which -- like the city of Atlanta -- are within the confines of DeKalb and Fulton Counties.  C&S decided to convert the six 5-percent banks at issue here into de jure branches.  C&S applied to the FDIC for permission to acquire all of the assets, and to assume all of the liabilities, of the 5-percent banks. [Footnote 6]  On October 4, 1971, after reviewing reports on the proposed acquisitions from the Federal Reserve Board, the Comptroller of the Currency, and the Justice Department, the FDIC approved C&S's acquisition of the five suburban banks which C&S had helped to found, but disapproved acquisition of the Tucker Bank.  Because the Tucker Bank had enjoyed an independent existence before being converted into a 5-percent bank, the FDIC concluded that the correspondent associate affiliation there had been "anticompetitive in its origins," and should not be "ratified" by approval of outright Page 422 U. S. 95 acquisition. [Footnote 7]  As for the five banks which C&S had helped to found, however, the FDIC stated:"[T]he opening of these . . . de novo banks served the convenience and needs of their respective communities and enhanced competition. . . ."The FDIC noted that the C&S system was the largest commercial banking institution in Fulton County and in DeKalb County. [Footnote 8]  For this reason, it observed,"new acquisitions of nonaffiliated banks in the same market [by C&S] would raise the most serious competitive problems under the Bank Merger Act as amended and under Section 7 of the Clayton Act."But the FDIC reasoned that the acquisitions proposed by C&S did not raise such problems, because the banks involved in the proposed mergers "do not compete today and never have competed"; further, there existed "no reasonable probability" that any of the 5-percent banks would break their ties with the C&S system even if the proposed acquisitions were disapproved.  Thus,"[s]uch mergers would not alter the existing competitive structure . . . in any way or add to the concentration of banking resources now held by the C&S system."II. The Suit in the District CourtOn November 2, 1971, within the 30-day period prescribed for such suits, 12 U.S.C. §§ 1828(c)(6) and (7), Page 422 U. S. 96 the United States filed a complaint in the District Court for the Northern District of Georgia, alleging that the five acquisitions approved by the FDIC would violate § 7 of the Clayton Act and that the ongoing correspondent associate relationships between C&S and the six 5-percent banks which it had originally sought to acquire constituted unreasonable restraints of trade, in violation of § 1 of the Sherman Act.  The Government sought injunctive relief prohibiting the proposed acquisitions and terminating the alleged violations of the Sherman Act.  On January 24, 1974, after an extensive trial, the District Court entered a judgment for the defendants.  372 F. Supp. 616, 643.As to the Sherman Act allegations, the District Court based its judgment upon two separate and independent grounds.  First, it held that the 1968 "understanding" between the staff of the Federal Reserve Board and C&S insulated the correspondent associate relationship between C&S and the 5-percent banks from attack under the antitrust laws.  Id. at 627.  The court based this conclusion on the following statement in Whitney Bank v. New Orleans Bank, 379 U. S. 411,  379 U. S. 419:"We believe Congress intended the statutory proceedings before the [Federal Reserve] Board to be the sole means by which questions as to the organization or operation of a new bank by a bank holding company may be tested."Alternatively, assuming the Sherman Act applied, the District Court found that the United States had failed to prove that the correspondent associate relationships involved "collusive price-fixing" or "any agreements not to compete or for market division." [Footnote 9]  The court held Page 422 U. S. 97"that the matters complained of are subject to the 'rule of reason,' [and] . . . the Government has not sustained its burden of proof as to the unreasonableness of the practices involved or with respect to any adverse impact upon competition."372 F. Supp.  at 627-628.The Government had conceded that it was no violation of the Sherman Act for a large city bank to arrange a traditional "correspondent" relationship with a smaller, Page 422 U. S. 98 outlying bank -- a"'mutually beneficial arrangement whereby the smaller bank receives needed services and the larger bank obtains both the benefit of the correspondent bank balance kept with it and the income from the sale of its services to the smaller bank's customers.'"Id. at 628.  Noting this concession, the District Court observed:"[S]uch assistance to, or sponsorship of, a smaller bank, is desirable and necessary, and not anticompetitive.  The difference between a pure correspondent relationship and a correspondent associate relationship as set forth in the evidence is merely one of degree, a fine line of demarcation almost impossible for the Court to perceive. . . ."". . .  [T]he Court finds as a fact that the relationship between C&S National, C&S Holding, and the five percent defendant banks, and the interchange of information between them, have been reasonable under the circumstances, and not in violation of Section 1 of the Sherman Act."Ibid.Turning to the claim under § 7 of the Clayton Act, the court found that the various defendant banks were each "engaged in commerce," and that the relevant "line of commerce" was "commercial banking."  The court declined, however, to define the appropriate geographic markets, stating that its "disposition of the case is based upon factors which make a precise delineation of the market area unnecessary."  372 F. Supp.  at 629.  Simply assuming the correctness of the Government's position that the appropriate markets were DeKalb County, Fulton County, North Fulton County, or the Atlanta area generally, the court made detailed findings as to the effect of the proposed acquisitions on C&S's nominal market shares.  Id. at 629-633. [Footnote 10]  But, just as had the FDIC Page 422 U. S. 99 before it, the court saw these increases in nominal shares as of no competitive significance, because the 5-percent banks had always been de facto branches within the C&S system.  Id. at 633-638. [Footnote 11] Page 422 U. S. 100IIIThe Issues Under the Sherman and Clayton ActsIt is common ground in this case that the 5-percent banks have been operated from the outset substantially as de facto branches of C&S, even though they are and have always been separate corporate entities.  From these agreed-upon facts, the parties draw sharply divergent conclusions under the Sherman and Clayton Acts.  Section 1 of the Sherman Act, 15 U.S.C. § 1, provides:"Every contract, combination in the form of trust or otherwise, or conspiracy, in restraint of trade or commerce among the several States . . . is declared to be illegal. . . ."The Government contends that the relationships between C&S and the six 5-percent banks constituted unreasonable restraints of trade on two alternative theories:  (1) the relationships encompassed an agreement to fix interest rates and service charges among the 5-percent banks, and between these banks and C&S-owned banks, resulting in a "per se" violation of the Sherman Act; (2) the programs unreasonably restrained interbank competition as to prices and services by extending interbank cooperation far beyond the conventional "correspondent" arrangements which large city banks traditionally make with small banks in outlying markets.  C&S denies that its relationships with the 5-percent banks encompassed any agreements to fix prices, and contends that the process of de facto branching was a procompetitive response to Georgia's anticompetitive ban on de jure branching, and thus legal under the Sherman Page 422 U. S. 101 Act's "rule of reason."  In the alternative, C&S contends that its relationships with the 5-percent banks were subject to the "exclusive primary jurisdiction" of the Federal Reserve Board, and thus immune from attack under § 1 of the Sherman Act.Section 7 of the Clayton Act, 15 U.S.C. § 18, provides:"No corporation engaged in commerce shall acquire, directly or indirectly, the whole or any part of the stock or other share capital and no corporation subject to the jurisdiction of the Federal Trade Commission shall acquire the whole or any part of the assets of another corporation engaged also in commerce, where in any line of commerce in any section of the country, the effect of such acquisition may be substantially to lessen competition, or to tend to create a monopoly. [Footnote 12]"The Government argues that the acquisitions of the five suburban banks approved by the FDIC would "lessen" competition when compared to what the situation would be if the defendant banks ceased their alleged Page 422 U. S. 102 violations of the Sherman Act.  The Government further contends that, even if the present relationships between C&S and the 5-percent banks do not offend the Sherman Act, since the relationships might nevertheless change and the whole situation become more competitive for business or state law reasons, the proposed acquisitions violate § 7 by foreclosing this possibility.  C&S argues that the acquisitions would merely convert de facto into de jure branches, with no perceptible effect on competition compared with the present situation, which is asserted by C&S to be lawful under the Sherman Act.  C&S urges that there is no realistic possibility of future competition among the defendant banks.  In the alternative, C&S contends that each of the 5-percent banks operates in a distinct and segregable market, so that the proposed acquisitions would not lessen competition in any relevant "section of the country," and that any anticompetitive effects of the acquisitions are "outweighed in the public interest" because the acquisitions meet "the convenience and needs" of banking customers in the Atlanta area. [Footnote 13]  The District Court did not reach these alternative contentions.A. The Sherman Act Issues1. The Question of ImmunityThe District Court thought the correspondent associate programs immune from Sherman Act scrutiny because they were subject to the "exclusive primary jurisdiction" of the Federal Reserve Board under the Bank Holding Company Act of 1956, as amended.   We do not so understand the law.  The court relied on Whitney Bank v. New Orleans Bank, 379 U. S. 411, but the question in that case was the wholly different one of whether it is the Comptroller of the Currency or the Page 422 U. S. 103 Federal Reserve Board that has jurisdiction to determine whether transactions by a bank holding company conform with applicable state banking law. F or guidance as to antitrust immunities, recourse must be had directly to the provisions of the Bank Holding Company Act, 12 U.S.C. § 1841 et seq.The statutory scheme requires the "prior approval" of the Federal Reserve Board for certain transactions by bank holding companies -- including transactions tending to create or enlarge holding company control of independent banks.  12 U.S.C. § 1842(a). [Footnote 14]  The types of transactions requiring Board approval were expanded by amendments to the Act in 1966 and 1970. [Footnote 15]  Prior to Page 422 U. S. 104 1966, it appeared that Board approval of a transaction provided no immunity from antitrust action, for a note then set out under 12 U.S.C. § 1841 stated that nothing in the Act was to be construed as a "defense" to an antitrust suit.  The 1966 amendments to the Act formalized this provision, but also blunted its force by establishing an intricate procedure for accommodating the jurisdictions of the Board and the Justice Department. [Footnote 16]  Under Page 422 U. S. 105 the Act as amended, the Board "shall not approve" an otherwise forbidden transaction unless it meets certain antitrust standards derived from, but not everywhere identical to, the standards of the Sherman Act and of § 7 of the Clayton Act.  12 U.S.C. § 1842(c).  The Board's Page 422 U. S. 106 order granting or denying an application for prior approval is subject to review in the courts of appeals.  12 U.S.C. § 1848.  Furthermore, an approved transaction is stayed automatically for 30 days, during which time an antitrust suit challenging the transaction may be brought in the district court.  12 U.S.C. § 1849(b).  Such a suit is governed by the modified antitrust standards set out in § 1842(c).  If the antitrust suit is not brought within 30 days, and the transaction is consummated,"the transaction may not thereafter be attacked in any judicial proceeding on the ground that it alone and of itself constituted a violation of any antitrust laws other than section 2 of Title 15 [ § 2 of the Sherman Act], but nothing in this chapter shall exempt any bank holding company involved in such a transaction from complying with the antitrust laws after the consummation of such transaction."12 U.S.C. § 1849(b).C&S can draw no consolation from these provisions.  It is true that the staff of the Federal Reserve Board, in 1968, came to an "understanding" with C&S that the correspondent associate programs then in effect did not offend § 3 of the Bank Holding Company Act, 12 U.S.C. § 1842(a), and thus did not require formal Board "approval." [Footnote 17]  But this did not give rise to any Page 422 U. S. 107 antitrust immunity.  A consummated transaction acquires immunity under § 1849(b) only when no antitrust action has been commenced within 30 days after Page 422 U. S. 108 the transaction has received the "approval" of the Board, in an order which is subject to judicial review and which reflects application by the Board. of the special antitrust standards of § 1842(c).  The immunity applies only to "an acquisition, merger, or consolidation transaction approved under section 1842 of this title in compliance with this chapter."  § 1849(b).  The obvious purpose of the complex machinery in § 1849(b) is to accord finality to formal actions of the Board not subjected to timely challenge under the antitrust laws.  There is no indication that Congress wished to accord a similar finality to the informal views of the Board's staff.We note, however, that the 1966 amendments also added a "grandfather" provision to the Bank Holding Company Act, 12 U.S.C. § 1849(d):"Any acquisition, merger, or consolidation of the kind described in section 1842(a) of this title which was consummated at any time prior or subsequent to May 9, 1956, and as to which no litigation was initiated by the Attorney General prior to July 1, 1966, shall be conclusively presumed not to have been in violation of any antitrust laws other than section 2 of Title 15 [§ 2 of the Sherman Act]."Unlike § 1849(b), this provision does not state or imply that the covered transactions must have received the formal approval of the Federal Reserve Board.  This grandfather provision is not, like § 1849(b), an attempt to accommodate the competing jurisdictions of the Federal Reserve Board under § 1842 and the Justice Department under the antitrust laws.  Rather, the grandfather provision is a simple conferral of legislative amnesty for Page 422 U. S. 109 theretofore unchallenged transactions completed before Congress had clarified the nature of that accommodation.The transactions by which C&S created a correspondent associate relationship with three of the 5-percent banks -- the Sandy Springs, Chamblee, and Tucker banks -- were consummated prior to July, 1966, and the Attorney General had taken no action against those transactions by that date.  Those transactions thus fall within the terms of the grandfather provision, and the correspondent associate programs in force at those three banks are, therefore, immune from attack under § 1 of the Sherman Act.While the formation by C&S of a de facto branch was a unique type of transaction, it may fairly be characterized as an "acquisition, merger, or consolidation of the kind described in § 1842(a)."  Forming a de facto branch was a multifaceted operation -- involving a multiplicity of purchases of stock by a number of parties, the adoption of the C&S logogram by the de facto branch, the connection of the de facto branch with C&S personnel and information programs, the structuring of the bank to receive and administer all C&S banking services, and the establishment of formal C&S influence over the board of directors at the de facto branch.  But even before its scope was expanded in 1970, § 1842(a) was concerned with more than the literal "acquisition" of stock:  it took broad account of the "indirect" control of stock, and the control of boards of directors "in any manner," by bank holding companies. [Footnote 18]  The grandfather provision creates immunity under § 1 of the Sherman Act, not simply under § 7 of the Clayton Act, an indication that its protection extends not merely to literal acquisitions, mergers, and consolidations, but also to "restraints of trade" simultaneous with and functionally Page 422 U. S. 110 integral to such transactions.  Though multifaceted, the formation by C&S of a de facto branch was a unitary and cohesive undertaking in the sense that all the facets were closely coordinated, simultaneously instituted, and designed to serve the single purpose of fitting the new bank into the "C&S system."  There is virtually nothing about the present correspondent associate programs that was not fully evident and in place from the moment the programs were launched.  There has been no increase in C&S control, nor any change in the way it has been exercised.Whether these programs violated § 1842(a) -- as it applies today or as it applied when the programs began -- is not relevant to our inquiry. [Footnote 19]  By its terms, the grandfather provision applies to transactions of the kind described in § 1842(a).  We cannot believe that Congress wished to grant the benefits of the provision only to transactions that plainly transgressed § 1842(a).  Such a construction would make application of the grandfather provision not only cumbersome and time consuming, [Footnote 20] but also flagrantly inequitable.  The formation of a de facto C&S branch involved the direct and Page 422 U. S. 111 indirect acquisition of bank stock, and the direct and indirect assertion of control over the governance and operations of a bank, by a bank holding company.  Though unusual in form, such a transaction quite clearly falls within the class of dealings by bank holding companies which Congress intended, in § 1849(d), to shield from retroactive challenge under the antitrust laws.2. De Facto Branching Under the Sherman ActThree of the 5-percent banks -- the Park National, South DeKalb, and North Fulton banks -- were formed after July 1, 1966, and their correspondent associate relationships with C&S are therefore beyond the reach of the grandfather provision of the Bank Holding Company Act and subject to scrutiny under the Sherman Act.Each of these banks was founded ab initio through the sponsorship of C&S.  Except for that sponsorship, they would very probably not exist.  The record shows that other banking organizations had been unsuccessful in attempting to launch new banks in the area, and C&S affiliation and financial backing were instrumental in convincing state and federal banking authorities to charter these new banks.  In short, these banks represented a policy by C&S of de facto branching through the formation of new banking units, rather than through the acquisition, and consequent elimination, of preexisting independent banks. [Footnote 21]Of necessity, the Government's attack on this process Page 422 U. S. 112 is highly technical.  Had the new banks been de jure branches of C&S, the whole process would have been beyond reproach.  Branching allows established banks to extend their services to new markets, thereby broadening the choices available to consumers in those markets. [Footnote 22]  Having access to parent-bank financial support, expert advice, and proved banking services, branches of several city banks can often enter a market not yet large or developed enough to support a variety of independent unit banks.  Branching thus offers competitive choice to markets where monopoly or oligopoly might otherwise prevail.  Furthermore, the branching process gives to outlying customers the benefit of sophisticated services which local unit banks might have little ability or incentive to deliver.  The Government denies none of this, nor that C&S's program of de facto branching was, until 1970, the closest substitute to de jure branching allowed under Georgia law.  Yet the Government insists that this de facto branching violated the Sherman Act because the parent bank and its de facto branches were legally distinct corporate entities and were obligated, therefore, to compete vigorously against each other.It is, of course, conceded that C&S's de facto branches have not behaved as active competitors with respect either to each other or to C&S National and its majority-owned affiliates.  But the Government goes further, and contends that the correspondent associate programs have actually encompassed at least a tacit agreement to fix interest rates and service charges, see Interstate Circuit, Inc. v. United States, 306 U. S. 208,  306 U. S. 227; United States v. Masonite Corp., 316 U. S. 265,  316 U. S. 275-276; United States v. Bausch & Lomb Optical Co., 321 U. S. 707,  321 U. S. 723; United States v. General Motors Corp., 384 U. S. 127, Page 422 U. S. 113 384 U. S. 142-143, so as to make the interrelationships -- to that extent at least -- illegal "per se."  See United States v. Socony-Vacuum Oil Co., 310 U. S. 150,  310 U. S. 224-226, n. 59; United States v. Parke, Davis & Co., 362 U. S. 29,  362 U. S. 47.  C&S vigorously denies the existence of any agreement to fix prices.  The evidence in the record is mixed.C&S did regularly notify the 5-percent banks -- as it did its de jure branches -- of the interest rates and service charges in force at C&S National and its affiliates.  But the dissemination of price information is not itself a per se violation of the Sherman Act.  See Maple Flooring Assn. v. United States, 268 U. S. 563; Cement Mfrs. Protective Assn. v. United States, 268 U. S. 588; United States v. Container Corp., 393 U. S. 333,  393 U. S. 338 (concurring opinion).  A few of the memoranda distributed by C&S could be construed as advocating price uniformity; on the other hand, the memoranda were, almost without exception, stamped "for information only," and the 5-percent banks were admonished by C&S, several times and very clearly, to use their own judgment in setting prices; indeed, the banks were warned that the antitrust laws required no less.  The District Court observed that, in fact, prices did not often vary significantly among the 5-percent banks or between these banks and C&S National, but the court attributed this to the "natural deference of the recipient to information from one with greater expertise or better services."  372 F. Supp.  at 628.  And the court found as a fact that there was no "collusive price-fixing."  Id. at 626.Were we dealing with independent competitors having no permissible reason for intimate and continuous cooperation and consultation as to almost every facet of doing business, the evidence adduced here might well preclude a finding that the parties were not engaged in a Page 422 U. S. 114 conspiracy to affect prices.  But, as we indicate below, the correspondent associate programs, as such, were permissible under the Sherman Act.  In this unusual light, we cannot hold clearly erroneous the District Court's finding that the lack of significant price competition did not flow from a tacit agreement, but instead was an indirect, unintentional, and formally discouraged result of the sharing of expertise and information which was at the heart of the correspondent associate programs.  Fed.Rule Civ.Proc. 52(a); United States v. General Dynamics Corp., 415 U. S. 486,  415 U. S. 508.The Government argues, alternatively, that the correspondent associate programs have gone far beyond conventional "correspondent" relationships, and that, consequently, these programs have "unreasonably" restrained competition among the 5-percent banks and between these banks and C&S National.  The District Court was not persuaded by this theory:"The difference between a pure correspondent relationship and a correspondent associate relationship as set forth in the evidence is merely one of degree, a fine line of demarcation almost impossible for the Court to perceive. . . .  In either case, there is the flow of information as to rates, practices, etc., which the Government apparently applauds or at least condones in a correspondent banking relationship."372 F. Supp.  at 628.The court's dilemma is understandable, for in neither law nor banking custom has there developed a clear, fixed definition of the correspondent relationship: [Footnote 23]"Correspondent banking is an interbank practice whereby 'city' correspondent banks provide a cluster Page 422 U. S. 115 of services to smaller 'country' banks in exchange for interbank deposits.  Dating back to colonial times, correspondent banking originally provided an extended network of independent unit banks with a link to financial centers, and at the same time furnished substitute central banking functions.  Today, as a vital component of the era of electronic banking, it enables city correspondents to provide customers with a range of services that is varied, extensive and constantly expanding; one survey lists as many as fifty different categories."Among the services typically provided within a conventional correspondent arrangement are check clearing, help with bill collections, participation in large loans, legal advice, help in building securities portfolios, counseling as to personnel policies, staff training, help in site selection, auditing, and the provision of electronic data processing.  Furthermore, like C&S's program, the correspondent arrangement is often established as a prelude to a formal merger between the two banks. [Footnote 24]Nevertheless, C&S's program does appear to have gone several steps beyond conventional correspondent arrangements.  Page 422 U. S. 116 C&S has closely advised the boards of directors of the 5-percent banks, supplied their chief executive officers, allowed full "branch-like" use of the C&S logogram, provided all the C&S services available at a de jure branch, dealt with the 5-percent banks through the C&S branch administration department, and provided constant and detailed information on prices and on all banking procedures. [Footnote 25]  It is conceivable that these relationships, separately or taken together, have restrained competition among the defendant banks more thoroughly or effectively than would have a conventional correspondence program.  But even if the Government had proved this, which the District Court found not to be the case, that alone would not make out a Sherman Act violation.  C&S has operated the 5-percent banks as de facto branches as a direct response to Georgia's historic restrictions on de jure branching, and the question therefore remains whether restraints of trade integral to this particular, unusual function are unreasonable.  See Chicago Board of Trade v. United States, 246 U. S. 231,  246 U. S. 238.  We turn directly to that question.The central message of the Sherman Act is that a business entity must find new customers and higher profits through internal expansion -- that is, by competing successfully, rather than by arranging treaties with its competitors.  This Court has held that even commonly owned firms must compete against each other if they hold themselves out as distinct entities.  "The corporate interrelationships of the conspirators . . . are not determinative of the applicability of the Sherman Act."  United States v. Yellow Cab Co., 332 U. S. 218,  332 U. S. 227.  See also Kiefer-Stewart Co. v. Joseph E. Seagram & Sons, Page 422 U. S. 117 Inc., 340 U. S. 211,  340 U. S. 215; Timken Roller Bearing Co. v. United States, 341 U. S. 593,  341 U. S. 598; Perma Life Mufflers, Inc. v. International Parts Corp., 392 U. S. 134,  392 U. S. 141-142.  A fortiori, independently owned firms cannot escape competing merely by pretending to common ownership or control, for the pretense would simply perfect the cartel.  We may also assume, though the question is a new one, that a business entity generally cannot justify restraining trade between itself and an independently owned entity merely on the ground that it helped launch that entity by providing expert advice or seed capital.  Otherwise, the technique of sponsorship followed by restraint might displace internal growth as the normal and legitimate technique of business expansion, with unknowable consequences.But these general principles do not dispose of the present case.  C&S was absolutely restrained by state law from reaching the suburban market through the preferred process of internal expansion.  De facto branching was the closest available substitute. [Footnote 26]  Just last Term, in a brief presented to this Court, the Justice Department told us that it was desirable and procompetitive for a bank to"[enter] de novo into areas foreclosed to branching by sponsoring the organization of an affiliate bank, and later acquiring the bank.  This method of expansion is legal and a well recognized practice used by large state-wide banking organizations, and recognized by the federal banking authorities. [Footnote 27]"The Page 422 U. S. 118 Government acknowledged that such a sponsored bank could "be affiliated with its sponsor for purposes of correspondent relationships and other inter-bank services, including financial support," and that it could be "formed" by the parent bank's "officers, directors, or their associates," and could be "assisted" by the parent firm "until acquired and converted into a branch." [Footnote 28]  This is as good a curbstone description as any of precisely the relationships at issue in the present case. [Footnote 29]To characterize these relationships as an unreasonable restraint of trade is to forget that their whole purpose and effect were to defeat a restraint of trade.  Georgia's anti-branching law amounted to a compulsory market division.  Accomplished through private agreement, market division is a per se offense under the Sherman Act:"This Court has reiterated time and again that '[h]orizontal territorial limitations . . . are naked restraints of trade with no purpose except stifling of competition.'"United States v. Topco Associates, Inc., 405 U. S. 596,  405 U. S. 608, quoting White Motor Co. v. United States, 372 U. S. 253,  372 U. S. 263.The obvious purpose and effect of a rigid anti-branching law are to make the potential bank customers of suburban, small town, and rural areas a captive market for small unit banks. [Footnote 30]  C&S devised a strategy to circumvent Page 422 U. S. 119 this statutory barrier.  By providing new banking options to suburban Atlanta customers while eliminating no existing options, the de facto branching program of C&S has plainly been procompetitive.The Government suggests that a "conventional" correspondent relationship between C&S and the 5-percent banks would have been equally procompetitive, and would have had the added virtue of facilitating competition among the 5-percent banks and between them and C&S National.  This is mere speculation on the present record.  Moreover, it is far from clear that a conventional correspondent relationship would have allowed C&S to put its full range of services into the suburban market, which, in light of the anti-branching law, was the very point of its policy and program.  Putting to one side the total lack of realism in suggesting that C&S might have founded new banks that would have competed vigorously with it and with each other, cf. United States v. Penn-Olin Chemical Co., 378 U. S. 158 169, the Government's argument wholly disregards C&S's ultimate goal of acquiring the new banks outright as soon as legally possible, a goal which the Government last year thought wholly proper.  We hold that, in the face of the stringent state restrictions on Page 422 U. S. 120 branching, C&S's program of founding new de facto branches, and maintaining them as such, did not infringe § 1 of the Sherman Act.B. The Clayton Act ClaimIn the light of the previous discussion, disposition of the Clayton Act claim becomes relatively straightforward.  The issue under § 7 of the Clayton Act is whether the effect of the proposed acquisitions, approved by the FDIC, "may be substantially to lessen competition . . . in any line of commerce in any section of the country."The Government established that C&S is the predominant banking institution in DeKalb County, Fulton County, North Fulton County, and the Atlanta area generally; that, in these markets, the commercial banking industry is quite highly concentrated in terms of market share statistics; and, of course, that the proposed acquisitions would increase C&S's nominal market shares. [Footnote 31]  The District Court did not decide whether the geographic markets proposed by the Government were the appropriate ones.  But assuming, arguendo, that they were, the Government plainly made out a prima facie case of a violation of § 7 under several decisions of this Court.  See United States v. Philadelphia National Bank, 374 U. S. 321,  374 U. S. 362-366; United States v. Phillipsburg National Bank & Trust Co., 399 U. S. 350,  399 U. S. 365-367; United States v. General Dynamics Corp., 415 U.S. at  415 U. S. 497.  It was thus incumbent upon C&S to show that the market share statistics gave an inaccurate account of the acquisitions' probable effects on competition.  United States v. General Dynamics Corp., supra at  415 U. S. 497-498; United States v. Marine Bancorporation, 418 U.S. at  418 U. S. 631.  The District Court, like Page 422 U. S. 121 the FDIC before it, concluded that C&S had made the necessary showing that these proposed acquisitions would not "lessen" competition for the simple reason that, under the correspondent associate program that had been continuously in effect, no real competition had developed or was likely to develop among the 5-percent banks or between these and C&S National.As to present and past competition, the Government agrees there is and has been none.  If this state of affairs were the result of violations of the Sherman Act, we agree with the Government that making the evil permanent through acquisition or merger would offend the Clayton Act.  See Citizen Publishing Co. v. United States, 394 U. S. 131,  394 U. S. 135.  But we have already concluded that C&S's program of founding and maintaining new de facto branches in the face of Georgia's anti-branching law did not violate the Sherman Act, and the de facto branches which C&S proposes to acquire were all founded ab initio with C&S sponsorship.  It thus indisputably follows that the proposed acquisitions will extinguish no present competitive conduct or relationships.  See United States v. Trans Texas Bancorporation, 412 U.S. 946, aff'g per curiam 1972 Trade Cas. 74,257 (WD Tex.).As for future competition, neither the District Court nor the FDIC could find any realistic prospect that denial of these acquisitions would lead the defendant banks to compete against each other.  The 5-percent banks theoretically could break their ties with C&S and its correspondent associate program, for these banks are each independently owned, but the record shows that none of the shareholders, directors, or officers of the 5-percent banks expressed any inclination to do so, and there was no evidence that the program has been other than beneficial and profitable for both C&S and the 5-percent banks. [Footnote 32]  Page 422 U. S. 122 The Clayton Act is concerned with "probable" effects on competition, not with "ephemeral possibilities."  Brown Shoe Co. v. United States, 370 U. S. 294,  370 U. S. 323.For the reasons set out in this opinion, the judgment of the District Court is affirmed.It is so ordered
U.S. Supreme CourtUnited States v. Citizens & Southern Nat'l Bank, 422 U.S. 86 (1975)United States v. Citizens & Southern National BankNo. 73-1933Argued March 19, 1975Decided June 17, 1975422 U.S. 86SyllabusTo circumvent Georgia's longstanding stringent restrictions on city banks' opening branches in suburban areas, appellee Citizens & Southern National Bank (C&S National) formed a holding company, which then embarked on a program of forming de facto branch banks in Atlanta's suburbs.  This program included the holding company's ownership of 5 percent of the stock of each of the suburban banks, ownership of much of the remaining stock by parties friendly to the C&S system of banking entities (hereafter C&S), the suburban banks' use of the C&S logogram and of all C&S's banking services, and close C&S oversight of the suburban banks' operation and governance.  In 1970, Georgia amended its banking statutes so as to allow de jure branching upon a county-wide basis.  This meant that C&S could now absorb the 5-percent banks as true branches, because Atlanta is contained within the two counties encompassing the suburbs in which the 5-percent banks operated.  Consequently C&S applied to the Federal Deposit Insurance Corporation (FDIC) under the Bank Merger Act of 1966 for permission to acquire all the stock of six of the 5-percent banks historically operated as de facto branches or "correspondent associate" banks within the C&S system.  The FDIC authorized five of the proposed acquisitions.  The Government then brought suit in District Court for injunctive relief, alleging that the five acquisitions would lessen competition in relevant banking markets in violation of § 7 of the Clayton Act, and that the historic de facto branch relations between C&S and the six 5-percent banks constituted unreasonable restraints of trade in violation of § 1 of the Sherman Act.  The court rendered judgment for C&S.  Three of the 5-percent banks were formed prior to, and three after, July 1, 1966.  The "grandfather" provision of the Bank Holding Company Act, 12 U.S.C. § 1849(d), as added by the 1966 amendments, provides that"[a]ny acquisition, merger, or consolidation of the kind described Page 422 U. S. 87 in [12 U.S.C. §] 1842(a). . . which was consummated at any time prior or subsequent to May 9, 1956, and as to which no litigation was initiated by the Attorney General prior to July 1, 1966, shall be conclusively presumed not to have been in violation of any antitrust laws other than"§ 2 of the Sherman Act.  Title 12 U.S.C. § 1842(a) makes it unlawful, absent the Federal Reserve Board's prior approval, for bank holding companies to engage in certain transactions, including those tending to create or enlarge holding company control of independent banks.Held:1. Since the Attorney General took no action by July, 1966, against the three 5-percent banks that were formed prior to that date, the transactions by which these banks became 5-percent banks fall within the terms of the grandfather provision of the Bank Holding Company Act, and therefore the correspondent associate programs in force at these banks are immune from attack under § 1 of the Sherman Act.  While C&S's formation of a de facto branch was a unique type of transaction, it may fairly be characterized as an "acquisition, merger, or consolidation of the kind described in [12 U.S.C. §] 1842(a)," and clearly falls within the class of dealings by bank holding companies that Congress intended, in the grandfather provision, to shield from retroactive challenge under the antitrust laws.  Pp.  422 U. S. 102-111.2. In the face of the stringent state restrictions on branching, C&S's program of founding new de facto branches, and maintaining them as such, did not infringe § 1 of the Sherman Act.  Pp.  422 U. S. 111-120.(a) Though the Government contends that the correspondent associate programs encompassed at least a tacit agreement to fix interest rates and service charges so as to make the interrelationships -- to that extent at least -- illegal per se, it cannot be held, in view of the mixed evidence in the record, and of the fact that such programs, as such, were permissible under the Sherman Act, that the District Court clearly erred in finding that the lack of significant price competition flowed not from a tacit agreement, but as an indirect, unintentional, and formally discouraged result of the sharing of expertise and information that was at the heart of the correspondent associate program.  Pp.  422 U. S. 112-114.(b) The Government's alternative contention, that the correspondent associate programs transcending conventional "correspondent" relationships "unreasonably" restrained competition Page 422 U. S. 88 among the 5-percent banks and between these banks and C&S National, is not persuasive, since, even if the Government had proved that such programs restrained competition among the defendant banks more thoroughly or effectively than would have a conventional correspondent program (which the District Court found not to be the case), that alone would not make out a Sherman Act violation.  Pp.  422 U. S. 114-116.(c) Where C&S has operated the 5-percent banks as de facto branches in direct response to Georgia's historic restrictions on de jure branching, restraints of trade integral to this particular, unusual function are not unreasonable.  To characterize the relationships at issue as an unreasonable restraint of trade is to forget that their whole purpose and effect were to defeat a restraint of trade, and by providing new banking options to suburban Atlanta customers, while eliminating no existing options, C&S's de facto branching program has plainly been procompetitive.  Pp.  422 U. S. 116-120.3. The proposed acquisitions will not violate § 7 of the Clayton Act.  Pp.  422 U. S. 120-122.(a) Since C&S's program of founding and maintaining new de facto branches in the face of Georgia's anti-branching law did not violate the Sherman Act, and since the de facto branches that C&S proposes to acquire were all founded ab initio with C&S sponsorship, it follows that the proposed acquisitions will extinguish no present competitive conduct or relationships.  P.  422 U. S. 121.(b) As for future competition, there is no evidence of any realistic prospect that denial of the acquisitions would lead the defendant banks to compete against each other, the Clayton Act being concerned with "probable" effects on competition, not with "ephemeral possibilities."  Pp.  422 U. S. 121-122.372 F. Supp. 616, affirmed.STEWART, J., delivered the opinion of the Court, in which BURGER, C.J., and MARSHALL, BLACKMUN, POWELL, and REHNQUIST, JJ., joined.  BRENNAN, J., filed a dissenting opinion, in which DOUGLAS and WHITE, JJ., joined, post, p.  422 U. S. 130. Page 422 U. S. 89