opinion: Mr. Justice Blackmun
  delivered the opinion of the Court.
  This case presents the question whether, when a public utility applies to the Federal Power Commission for authority to issue a security, as the utility is required to do under § 204 of the Federal Power Act, 49 Stat. 850, 16 U. S. C. § 824c, the Commission, in passing upon the application, must consider the issue’s anticompetitive effect in determining whether it is “compatible with the public interest,” as that phrase is employed in § 204 (a).
  I
  In October 1970, Gulf States Utilities Company applied to the Federal Power Commission for authority to issue for cash, on competitive bidding, $30,000,000 first mortgage 30-year bonds for the purpose of refunding part of Gulf’s then-outstanding commercial paper and short-term notes.
  Gulf, a Texas corporation qualified to do business in Louisiana, is a public utility within the meaning of § 201 (e) of the Federal Power Act, 16 U. S. C. § 824 (e). It is engaged principally in the business of generating, distributing, and selling electric energy in southeastern Texas and south central Louisiana in an area of approximately 28,000 square miles with a population of about 1,225,000. Gulf sells electric energy at retail in numerous communities in that market and, at the time of the application, was providing electric energy for resale to nine municipal systems, 11 rural electric cooperatives (one serving four municipal systems), and one other utility.
  The Commission filed notice of Gulf’s application. 35 Fed. Reg. 16649 (1970). Thereupon the cities of Lafayette and Plaquemine, Louisiana (Cities) filed a protest and petition to intervene in the proceedings before the Commission and requested a formal hearing on Gulf’s application. The Cities alleged that Gulf, in concert with two other investor-owned utilities, Louisiana Power and Light Company (LP&L) and Central Louisiana Electric Company (CLECO), had engaged in activities “apparently violative of the anti-trust laws,” as well as of § 10 (h) of the Federal Power Act, 16 U. S. C. § 803 (h), and of the Public Utility Holding Company Act of 1935, 49 Stat. 838, 15 U. S. C. § 79 et seq.; that these activities, in effect, would be “financed or refinanced by the bonds here proposed”; and that the utilities’ activities were incompatible with the public interest. The Cities opposed the requested authorization “unless and until Gulf States purges itself of these past violations, or unless the Commission conditions its authorization.”
  The Cities’ claim centered on and stressed a 1968 interconnection and pooling agreement between the Cities, Dow Chemical Company, and Louisiana Electric Cooperative, Inc. (LEC). Dow has a plant near the Cities; the plant has generating capacity that could be used by the other members of the pool as emergency stabilizing capacity. LEC is a generation and transmission electric cooperative financed by the Rural Electrification Administration (REA); it is a super-cooperative composed of 12 electric distribution cooperatives, all located in the area served by the three utilities.
  In 1964, the REA was considering loans to LEC for the construction of a generation station and transmission lines through which LEC would be able to serve eight of its 12 member organizations. These members were then purchasing their power from the three utilities. The Cities claimed that the three utilities had attempted to destroy LEC, and pointed to a history of “extraordinary litigation” instituted by the utilities between 1964 and 1970 to prevent the construction of the station and the lines, and in fact delaying that construction for five years. The arrangement proposed by the 1968 agreement would assure a market for the parties’ surplus capacity and would coordinate, at substantial savings, the construction of new generators by the parties. The three utilities, correspondingly, would lose substantial business if the 1968 arrangement were carried out. Accordingly, Cities alleged, the three utilities engaged in frivolous and repetitive litigation and launched a public relations and lobbying drive against LEC in order to block the loan and prevent fulfillment of the agreement. Cf. California Transport v. Trucking Unlimited, 404 U. S. 508 (1972).
  The REA loan was effected, however, in 1969. But by that time the loan was sufficient only for the generating facilities exclusive of the lines. Cities, Dow, and LEC, then were forced to negotiate with the three utilities for the use of the utilities’ lines to transmit their power. Cities contended that the three utilities continued, through the course of the negotiations, to block or limit the pool by agreeing only to provide transmission services to some of the pool members; by refusing to supply transmission facilities between pool members unless the 1968 pooling agreement were canceled; and by demanding that LEC limit its power capacity to the wattage already planned, thus giving the three utilities the exclusive right to supply all further power needs of LEC’s 12 cooperatives and precluding further expansion by LEC.
  Cities, by their proposed intervention, would bring these allegations before the Federal Power Commission in the § 204 proceeding. They claimed that such anti-competitive conduct was properly the subject of a § 204 proceeding and that, under § 204 (b), 16 U. S. C. § 824c (b), the Commission may condition its approval of the bond issue accordingly and place restrictions on Gulf’s use of the proceeds.
  By its answer, Gulf denied any violation of the antitrust laws, of the Federal Power Act, or of the Public Utility Holding Company Act of 1935. It alleged that the purpose of § 204 of the Federal Power Act was “to prevent unsound financing which might impair the financial integrity of public utilities,” and that even if the allegations of the Cities were accepted as true by the Commission, those matters were “irrelevant to this application.”
  By order issued December 3, 1970, 44 F. P. C. 1524, the Commission granted the Cities permission to intervene. It denied their request for a hearing, however, and it authorized the issuance and sale of the bonds. The order recited:
  “The requested approval of the issuance of the Bonds allow [sic] the Company only to change the form of a portion of its outstanding indebtedness, it does not call for the initiation of any construction or other program by the Company which might effect [sic] the interest of the Petitioners. The alleged violations which petitioners attempt to raise in this proceeding are irrelevant to a requested authorization of securities. There is no relief that the Commission can order in authorizing the issuance of the Bonds for refinancing purposes that would have any effect on the interest of the Petitioners, or solve any of the problems outlined by them.” Id., at 1525.
  The Commission specifically found:
  “The matters asserted and activities alleged in the filed protest and petition to intervene by the Cities of Lafayette and Plaquemine, Louisiana, are irrelevant to the purpose of issuing bonds to refund short-term indebtedness heretofore authorized by this Commission.” Id., at 1526.
  The petition for rehearing required by § 313 (a) of the Act, 16 U. S. C. § 825l (a), see Department of Fish & Game v. FPC, 359 F. 2d 165, 168-169 (CA9), cert, denied, 385 U. S. 932 (1966), was filed by the Cities, and was denied.
  Review was sought pursuant to § 313 (b) of the Act, 16 U. S. C. § 825l (b), in the United States Court of Appeals for the District of Columbia Circuit. A unanimous panel of that court disagreed with the Commission and remanded the case to it for consideration of the claims raised by the Cities, sub nom. City of Lafayette v. SEC, 147 U. S. App. D. C. 98, 454 F. 2d 941 (1971). The court recognized that the Commission’s contention that Gulf’s operations “could have no meaningful relation to an application that only sought to replace short-term notes with long term bonds” was “not without appeal, and also not without problems.” Id., at 109, 454 F. 2d, at 952. The court concluded, however, that the “cryptic statement of the FPC does not permit us to conclude with reasonable confidence that this was the position taken by the FPC.” Ibid. It observed that the Commission may have rejected the Cities’ allegations out of hand upon the authority of its earlier decision in Pacific Power & Light Co., 27 F. P. C. 623 (1962), a position the Court of Appeals viewed as untenable under this Court’s subsequent decision in Denver & R. G. W. R. Co. v. United States, 387 U. S. 485 (1967).
  Inasmuch as the decision of the Court of Appeals raised issues of potential and recurring importance with respect to the authorization of securities by the Federal Power Commission, we granted certiorari. 406 U. S. 956 (1972). The Commission took the position that the Court of Appeals was in error, but nevertheless opposed the grant.
  II
  The mandate that § 204 of the Federal Power Act, 16 U. S. C. § 824c, imposes upon the Commission is a broad and impressive one. Section 204 (a) empowers the Commission to authorize the issue of a security by a public utility only “if it finds that such issue ... is for some lawful object, within the corporate purposes of the applicant and compatible with the public interest.” This requires the Commission to inquire into and to be satisfied with the purposes of the issue and its lawfulness. And even if its “object” is lawful, the necessary inquiry is not ended, for, in addition, the object must be “compatible with the public interest.”
  In making its determination under § 204 (a), the Commission is given broad powers of inquiry and enforcement. By § 204 (b) it may hold hearings on the application, may grant the application “in whole or in part,” may modify it, and may impose such terms or conditions “as it may find necessary or appropriate.” After opportunity for hearing, and for good cause shown, it also may supplement, modify, or condition any previous order “as it may find necessary or appropriate.” Ibid. Section 204 (c) grants the Commission authority to specify the purpose to which the proceeds of the security may be applied and the amount allowed for that purpose. While, as Gulf observes, §§ 204 (e) and (f) exempt from § 204 (a) certain transactions that concern short-term obligations as well as public utilities that are “organized and operating in a State under the laws of which its security issues are regulated by a State commission,” these exemptions do not significantly detract from the sweeping powers and responsibilities of the Commission with respect to public utility security issues generally.
  We are asked to hold that the Commission’s responsibilities under § 204 do not extend to consideration on its part of possible anticompetitive consequences flowing from the issuance of a security. Gulf and the Commission both argue that administrative inquiry under § 204 is to be narrowly confined to the prevention of the issuance of a security that might impair the utility’s financial integrity or its ability to perform its public utility service and responsibilities. Exactly this interpretation was placed on § 204 by the Commission in 1962 in Pacific Power & Light Co., 27 F. P. C., at 626. Gulf and the Commission contend that antitrust considerations of the kind asserted by the Cities do not fall within the limited scope of § 204 as thus defined, and consideration by the Commission of such broad-ranging issues would be incompatible with the need for relatively fast action by the Commission when it passes upon a proposed security issue. It is said that allegations of anticompetitive conduct properly may be raised and fully considered in other proceedings related to interconnections under § 202 of the Act, 16 U. S. C. § 824a, to dispositions and mergers under § 203, 16 U. S. C. § 824b, to rates and rate-making practices under §§ 205 and 206, 16 U. S. C. §§ 824d and 824e, and to adequacy of service under § 207,16 U. S. C. § 824f.
  Although allegations similar to those raised here may, indeed, be made in such other proceedings under the Federal Power Act, we do not regard that fact as determinative of the scope of Commission inquiry under § 204. Instead, the Commission’s broad authority to consider anticompetitive and other conduct touching the “public interest” under the other sections of the Act emphasizes the breadth of its authority under the public interest standard generally and as embodied in § 204. This statute was enacted as part of Tit. II of the Public Utility Act of 1935, 49 Stat. 803, 850. The Act had two primary and related purposes: to curb abusive practices of public utility companies by bringing them under effective control, and to provide effective federal regulation of the expanding business of transmitting and selling electric power in interstate commerce. 49 Stat. 803-804, 847-848; S. Rep. No. 621, 74th Cong., 1st Sess., 1-4, 17-20; H. R. Rep. No. 1318, 74th Cong., 1st Sess., 3, 7-8; Jersey Central Co. v. FPC, 319 U. S. 61, 67-68 (1943); see North American Co. v. SEC, 327 U. S. 686 (1946). The Act was passed in the context of, and in response to, great concentrations of economic and even political power vested in power trusts, and the absence of antitrust enforcement to restrain the growth and practices of public utility holding companies. See S. Rep. No. 621, supra, at 11-12; Utility Corporations — Summary Report, 70th Cong., 1st Sess., S. Doc. No. 92, Part 73-A, pp. 47-54; 79 Cong. Rec. 8392 (1935).
  In order to achieve federal regulation of these and other perceived problems on the operational level of the interstate public utility business, Tit. II was enacted. S. Rep. No. 621, supra, at 17; H. R. Rep. No. 1318, supra, at 7. Part II of Tit. II was denominated the Federal Power Act, 49 Stat. 863. Title II certainly did not preclude the operation of the antitrust laws, and it vested the Federal Power Commission with important and broad regulatory power in the areas described above. See Otter Tail Power Co. v. United States, 410 U. S. 366 (1973); Meeks, Concentration in the Electric Power Industry: The Impact of Antitrust Policy, 72 Col. L. Rev. 64 (1972). This power clearly carries with it the responsibility to consider, in appropriate circumstances, the anti-competitive effects of regulated aspects of interstate utility operations pursuant to § § 202 and 203, and under like directives contained in §§205, 206, and 207. The Act did not render antitrust policy irrelevant to the Commission’s regulation of the electric power industry. Indeed, within the confines of a basic natural monopoly structure, limited competition of the sort protected by the antitrust laws seems to have been anticipated. See Otter Tail Power Co. v. United States, supra, at 373-374; California v. FPC, 369 U. S. 482 (1962); S. Rep. No. 621, supra, at 12; Hearings before the House Committee on Interstate and Foreign Commerce on H. R. 5423, 74th Cong., 1st Sess., 157-159 (1935); Summary Report, supra, at 52; Meeks, supra.
  Nothing in the Act suggests that the “public interest” standard of § 204 contains any less broad directive than that contained in the other similarly worded and adjacent sections. Under the express language of § 204 the public interest is stressed as a governing factor. There is nothing that indicates that the meaning of that term is to be restricted to financial considerations, with every other aspect of the public interest ignored. Further, there is the section’s requirement that the object of the issue be lawful. The Commission is directed to inquire into and to evaluate the purpose of the issue and the use to which its proceeds will be put. Without a more definite indication of contrary legislative purpose, we shall not read out of § 204 the requirement that the Commission consider matters relating to both the broad purposes of the Act and the fundamental national economic policy expressed in the antitrust laws. See FMC v. Svenska Amerika Linien, 390 U. S. 238, 244 (1968); California v. FPC, 369 U. S., at 484-485; FCC v. RCA Communications, Inc., 346 U. S. 86, 94 (1953); McLean Trucking Co. v. United States, 321 U. S. 67, 80 (1944). Cf. Report of National Power Policy Committee on Public-Utility Holding Companies, in S. Rep. No. 621, supra, at 55, 59 (App.). Consideration of antitrust and anticompetitive issues by the Commission, moreover, serves the important function of establishing a first line of defense against those competitive practices that might later be the subject of antitrust proceedings. This is particularly significant in the context of a security issue under § 204, for appropriate consideration at a pre-issue stage may avoid the need later to unravel complex transactions in granting relief under the antitrust laws or other sections of the Federal Power Act.
  Our conclusion is reinforced by the decision in Denver & R. G. W. R. Co. v. United States, 387 U. S. 485 (1967). In that case the Court concluded that the Interstate Commerce Commission, in performing its duty under § 20a (2) of the Interstate Commerce Act, 49 U. S. C. § 20a (2), to determine whether the issuance of a particular security is “for some lawful object . . . and compatible with the public interest,” is required, as a general rule, to consider the anticompetitive consequences of the issue. Section 204 of the Federal Power Act was modeled upon § 20a of the Interstate Commerce Act. The initial draft of § 204 was without any broad reference to the public interest. Instead, it identified four specific purposes for which a utility could issue a security (property acquisition; expansion or improvement of facilities or service; discharge or lawful refunding of obligations; and reimbursement of other expenditures for such purposes). H. R. 5423, § 206, 74th Cong., 1st Sess., 108-109; S. 1725, § 206, 74th Cong., 1st Sess., 109-110. This provision intentionally was replaced with the broader language now contained in § 204 in order “to attain greater flexibility and workability than would have been possible under the original section. The language defining the purposes for which securities may be issued has been taken substantially from section 20a of the Interstate Commerce Act, which has proved its usefulness.” S. Rep. No. 621, supra, at 20. There was, thus, a departure from the specific, and a selection of the general. We perceive no reason to view the responsibility placed on the FPC under § 204 differently from the ICC’s responsibility under § 20a of the Interstate Commerce Act. Each agency possesses broad regulatory authority. Each is charged with responsibility for considering antitrust policy under its statute. And § 204 and § 20a are virtually identical in language. The fact that the ICC has a specific obligation under § 11 (a) of the Clayton Act, 15 U. S. C. § 21 (a), to enforce § 7 of that Act, as well as a responsibility to advance the National Transportation Policy, did not control the decision in the Denver case, see 387 U. S., at 492-493, and the absence of a parallel reference in § 11 of the Clayton Act with respect to the FPC is not to be deemed controlling. Cf. California v. FPC, 369 U. S. 482 (1962).
  Ill
  Our conclusion that the FPC must consider anticompetitive aspects of a security issue to which § 204 applies does not end the inquiry, for two subordinate questions remain: whether the agency abused its authority in refusing to hold a hearing on the Cities’ objections, and whether, on the facts of this case, the Commission improperly rejected the Cities’ allegations out of hand on the ground that they were irrelevant to the security issue for which Gulf sought approval.
  Gulf asserts that even if the Commission is required to investigate and to consider the Cities’ objections under § 204, its refusal to do so here was not error, for the Commission may summarily dispose of objections of this kind without a hearing and extended investigation. Our conclusion that, as a general rule, the Commission must consider anticompetitive consequences of a security issue under § 204 does not mean that the Commission must hold a hearing on objections in every case. Neither does it mean that every allegation must be fully investigated regardless of its facial merit, or that consideration of the allegations may not, in appropriate circumstances, be deferred, or that the major portion of a securities issue may not forthwith be authorized and only the remainder withheld for further study. So strict a rule would unduly limit the discretion the Commission must have in order to mold its procedures to the exigencies of the particular case, and would be unrealistic in the light of the nature of a proceeding under § 204. The need for flexibility, planning, and rapid coordinated action is particularly acute with respect to the sale of a security on the market. But where the Commission summarily disposes of proffered objections, or where it exercises its discretion to approve an issue without considering its anti-competitive consequences, “the reviewing court must closely scrutinize its action in light of the . . . statutory obligations to protect the public interest and to enforce the antitrust laws. Whether or not an abuse of discretion is present must ultimately depend upon the transaction approved, its possible consequences, and any justifications for the deferral” or summary treatment. Denver, 387 U. S., at 498. Denver, as we have noted, concerned the ICC, but the foregoing quotation from that opinion has equally forceful application in the FPC context.
  Gulf also strenuously urges that the Commission in fact did consider Cities’ allegations, although summarily, and properly rejected them on their merits as having no relation to the security issue or to any possible future anticompetitive conduct in which Gulf might engage. We have noted above that the Court of Appeals observed, 147 U. S. App. D. C., at 109, 454 F. 2d, at 952, that certain aspects of this argument are not without substantial appeal. On the basis of the record before us, we cannot say that, upon consideration of the objections raised by the Cities, the Commission would not be justified in rejecting them summarily. But such summary action may not go unexplained in the face of the statutory obligation placed on the Commission under § 204. The decision the Commission thus far has made provides us with an inadequate explanation of its reasons for disposing of the Cities’ objections on their merits, if that in fact is what occurred. We are provided with no explanation of why summary action was warranted, and we are provided with no reason for the Commission’s possible conclusion that the objections were meritless. Without more, we are unable “closely [to] scrutinize” the Commission’s action. Nor may we supply an alternative, unstated ground to support an agency’s decision if that ground is one that “the agency alone is authorized to make.” SEC v. Chenery Corp., 318 U. S. 80, 88 (1943).
  The decision of the Court of Appeals in remanding the case to the Federal Power Commission is
  Affirmed.
  “§824e. Issuance of securities; assumption of liabilities; filing duplicate reports with Securities and Exchange Commission.
  “(a) No public utility shall issue any security . . . unless and until, and then only to the extent that, upon application by the public utility, the Commission by order authorizes such issue .... The Commission shall make such order only if it finds that such issue ... (a) is for some lawful object, within the corporate purposes of the applicant and compatible with the public interest, which is necessary or appropriate for or consistent with the proper performance by the applicant of service as a public utility and which will not impair its ability to perform that service, and (b) is reasonably necessary or appropriate for such purposes. . . .
  “(b) The Commission, after opportunity for hearing, may grant any application under this section in whole or in part, and with such modifications and upon such terms and conditions as it may find necessary or appropriate, and may from time to time, after opportunity for hearing and for good cause shown, make such supplemental orders in the premises as it may find necessary or appropriate, and may by any such supplemental order modify the provisions of any previous order as to the particular purposes, uses, and extent to which, or the conditions under which, any security so theretofore authorized or the proceeds thereof may be applied, subject always to the requirements of subsection (a) of this section.
  “(c) No public utility shall, without the consent of the Commission, apply any security or any proceeds thereof to any purpose not specified in the Commission’s order, or supplemental order, or to any purpose in excess of the amount allowed for such purpose in such order, or otherwise in contravention of such order.”
  Gulf, in its Securities and Exchange Commission registration statement for the bonds, stated that the proceeds received from the notes to be refinanced had been used “in connection with the Company’s construction program and for other corporate purposes.” App. 162. The notes themselves had been issued upon the authority of an uncontested order in FPC Docket E-7509. The Commission in that proceeding authorized a total of $80,000,000 in short-term debt. Only $55,000,000 of this was outstanding at the time of Gulf’s bond authorization proceeding. Thus, apart from the bond issue, Gulf could have borrowed another $25,000,000 in short-term credit without further Commission authorization.
  “Combinations, agreements, arrangements, or understandings, express or implied, to limit the output of electrical energy, to restrain trade, or to fix, maintain, or increase prices for electrical energy or service are hereby prohibited.”
  Cities also opposed an application of LP&L for approval by the Securities and Exchange Commission of bond and stock issues, the proceeds of which were to be used to repay short-term obligations and for other corporate purposes. Cities contended that the proceeds of these issues would be used for the construction of facilities that would further the unlawful objectives of LP&L, Gulf, and CLEC, and asked that approval by the SEC be conditioned on cessation of the illegal activities and the establishment of a program to remedy the damage already done.
  The jurisdiction of the SEC in this instance was based on §§ 6 and 7 of the Public Utility Holding Company Act of 1935, 15 U. S. C. §§ 79f and 79g, which are part of Tit. I of the Public Utility Act of 1935, 49 Stat. 803, 814-817. Sections 6 and 7 contain a number of requirements that must be met for SEC approval of a security issue. The most relevant of these is in § 7 (d), which requires that the SEC “shall permit a declaration ... to become effective unless the Commission finds that — . . . (6) the terms and conditions of the issue or sale of the security are detrimental to the public interest or the interest of investors or consumers.”
  The SEC refused to entertain the Cities’ protest, concluding that its authority under § 7 (d) (6) related solely to the terms and conditions of the security to be issued, and did not extend to collateral and unrelated controversies in which LP&L might be engaged. The Cities petitioned the United States Court of Appeals for the District of Columbia Circuit for review of the SEC orders, and the matter was consolidated with the present case. The Court of Appeals affirmed the SEC orders, but remanded Gulf’s case to the FPC. It explained this diverse treatment as follows:
  “Where an agency has some regulatory jurisdiction over operations, it must consider whether there is a reasonable nexus between the matters subject to its surveillance and those under attack on anti-competitive grounds. But the general doctrine requiring an agency to take account of antitrust considerations does not extend to a case like the one before us where the antitrust problem arises out of operations of the regulated company (past and projected) and the agency, here the SEC, has not been given any regulatory jurisdiction over operations of the company. The SEC has no jurisdiction over operations and stands in a different posture from the FPC which, as we have already noted, has regulatory jurisdiction over operations in view of its authority, inter alia, to direct utilities to interconnect on- reasonable .terms, or to prohibit a utility from discriminating in rates and facilities against its municipal customers” 147 U. S. App. D. C. 98, 112-113, 454 F. 2d 941, 955-956 (emphasis in original).
  These exemption provisions have no application to Gulf’s security issue challenged by the Cities here.
  Cf., however, Black Hills Power & Light Co., 28 F. P. C. 1121 (1962), and 31 F. P. C. 1605 (1964).
  “Sec. 206 (a). No public utility shall issue any security, or assume any obligation or liability as guarantor, indorser, surety, or otherwise in respect of any security of another person, unless and until, and then only to the extent that, upon application by the public utility, the Commission by order authorizes such issue or assumption of liability. The Commission shall make such order only if it finds that such issue or assumption of liability is for one or more of the following purposes and no others, and is reasonably necessary or appropriate for such purpose or purposes; the acquisition of property; the construction, completion, extension or improvement of the facilities or service of the public utility; the discharge or lawful refunding of its obligations; and the reimbursement of moneys actually expended from sources other than the issue of securities for any of the aforesaid purposes in cases where the applicant shall have kept its accounts and vouchers for such expenditures in such manner as to enable the Commission to ascertain the amount of moneys so expended and the purpose for which such expenditure was made.”
  The foregoing was the Senate version. Except for one spelling and two punctuational differences, the House version was identical.
  The FPC has so recognized. Pacific Power & Light Co., 27 F. P. C. 623, 627 (1962).
  The Court of Appeals meticulously outlined various options available to the Commission. 147 U. S. App. D. C., at 110-111, 454 F. 2d, at 953-954.