MR. JUSTICE REHNQUIST delivered the opinion of the Court.

Under the Securities Exchange Act of 1934, ch. 404, 48 Stat. 881, the Securities and Exchange Commission has the authority "summarily to suspend trading in any security . . . for a period not exceeding ten days" if "in its opinion the public interest and the protection of investors so require." Acting pursuant to this authority the Commission issued a series of consecutive orders suspending trading in the common stock of Canadian Javelin, Ltd. (CJL), for over a year. The Court of Appeals for the Second Circuit held that such a series of suspensions was beyond the scope of the Commission's statutory authority. 547 F.2d 152, 157-158 (1976). We granted certiorari to consider this important question, 434 U.S. 901 (1977), and, finding ourselves in basic agreement with the Court of Appeals, we affirm. We hold that even though there be a periodic redetermination of whether such action is required by "the public interest" and for "the protection of investors," the Commission is not empowered to issue, based upon a single set of circumstances, a series of summary orders which would suspend trading beyond the initial 10-day period.

I

On November 29, 1973, apparently because CJL had disseminated allegedly false and misleading press releases concerning certain of its business activities, the Commission issued the first of what was to become a series of summary 10-day suspension orders continuously suspending trading in CJL common stock from that date until January 26, 1975. App. 109. During this series of suspensions respondent Sloan, who owned 13 shares of CJL stock and had engaged in substantial purchases and short sales of shares of that stock, filed a petition in the United States Court of Appeals for the Second Circuit challenging the orders on a variety of grounds. On October 15, 1975, the court dismissed as frivolous all respondent's claims, except his allegation that the "tacking" of 10-day summary suspension orders for an indefinite period was an abuse of the agency's authority and a deprivation of due process. It further concluded, however, that in light of two events which had occurred prior to argument, it could not address this question at that time. The first event of significance was the resumption of trading on January 26, 1975. The second was the commencement of a second series of summary 10-day suspension orders, which was still in effect on October 15. This series had begun on April 29, 1975, when the Commission issued a 10-day order based on the fact that the Royal Canadian Mounted Police had launched an extensive investigation into alleged manipulation of CJL common stock on the American Stock Exchange and several Canadian stock exchanges. App. 11-12. This time 37 separate orders were issued, suspending trading continuously from April 29, 1975, to May 2, 1976. The court thought the record before it on October 15 inadequate in light of these events and dismissed respondent's appeal "without prejudice to his repleading after an administrative hearing before the SEC . . .," which hearing, though apparently not required by statute or regulation, had been offered by the Commission at oral argument. 527 F.2d 11, 12 (1975), cert. denied, 426 U.S. 935 (1976).

Thereafter respondent immediately petitioned the Commission for the promised hearing. The hearing was not forthcoming, however, so on April 23, 1976, during the period when the second series of orders was still in effect, respondent brought the present action pursuant to § 25(a)(1) of the Act, 15 U.S.C. § 78y (a)(1) (1976 ed.), challenging the second series of suspension orders. He argued, among other things, that there was no rational basis for the suspension orders, that they were not supported by substantial evidence in any event, and that the "tacking" of 10-day summary suspension orders was beyond the Commission's authority because the statute specifically authorized suspension "for a period not exceeding ten days." The court held in respondent's favor on this latter point. It first concluded that despite the fact that there had been no 10-day suspension order in effect since May 2, 1976, and the Commission had asserted that it had no plans to consider or issue an order against CJL in the foreseeable future, the case was not moot because it was "`capable of repetition, yet evading review.'" 547 F.2d, at 158, quoting from Southern Pacific Terminal Co. v. ICC, 219 U.S. 498, 515 (1911).

The court then decided that the statutes which authorized summary suspensions — § 12(k) and its predecessors — did not empower the Commission to issue successive orders to curtail trading in a security for a period beyond the initial 10-day period. 547 F.2d, at 157-158. We granted certiorari, specifically directing the attention of the parties to the question of mootness, 434 U.S. 901 (1977), to which we now turn.

II

Respondent argues that this case is not moot because, as the Court of Appeals observed, it is "capable of repetition, yet evading review." The Commission, on the other hand, does not urge that the case is demonstrably moot, but rather that there simply are not enough facts on the record to allow a proper determination of mootness. It argues that there is no "reasonable expectation" that respondent will be harmed by further suspensions because, "`the investing public now ha[ving] been apprised of the relevant facts, the concealment of which had threatened to disrupt the market in CJL stock, there is no reason to believe that it will be necessary to suspend trading again.'" Brief for Petitioner 15, quoting from Pet. for Cert. 12 n. 7. Cf. Weinstein v. Bradford, 423 U.S. 147, 149 (1975). The Commission concedes, however, that respondent, in his capacity as a diversified investor, might be harmed in the future by the suspension of some other security which he owns. But it further contends that respondent has not provided enough data about the number or type of securities in his portfolio to enable the Court to determine whether there is a "reasonable" likelihood that any of those securities will be subjected to consecutive summary suspension orders.

Contrary to the Commission's contention, we think even on the record presently before us this case falls squarely within the general principle first enunciated in Southern Pacific Terminal Co. v. ICC, supra, and further clarified in Weinstein v. Bradford, supra, that even in the absence of a class action a case is not moot when "(1) the challenged action was in its duration too short to be fully litigated prior to its cessation or expiration, and (2) there was a reasonable expectation that the same complaining party would be subjected to the same action again." Weinstein v. Bradford, supra, at 147 (emphasis added). That the first prong of this test is satisfied is not in dispute. A series of consecutive suspension orders may last no more than 20 days, making effective judicial review impossible during the life of the orders. We likewise have no doubt that the second part of the test also has been met here. CJL has, to put it mildly, a history of sailing close to the wind. Thus, the Commission's protestations to the contrary notwithstanding, there is a reasonable expectation, within the meaning of Weinstein v. Bradford, supra, that CJL stock, will again be subjected to consecutive summary suspension orders and that respondent, who apparently still owns CJL stock, will suffer the same type of injury he suffered before. This is sufficient in and of itself to satisfy this part of the test. But in addition, respondent owns other securities, the trading of which may also be summarily suspended. As even the Commission admits, this fact can only increase the probability that respondent will again suffer the type of harm of which he is presently complaining. It thus can only buttress our conclusion that there is a reasonable expectation of recurring injury to the same complaining party.

III A

Turning to the merits, we note that this is not a case where the Commission, discovering the existence of a manipulative scheme affecting CJL stock, suspended trading for 10 days and then, upon the discovery of a second manipulative scheme or other improper activity unrelated to the first scheme, ordered a second 10-day suspension. Instead it is a case in which the Commission issued a series of summary suspension orders lasting over a year on the basis of evidence revealing a single, though likely sizable, manipulative scheme. Thus, the only question confronting us is whether, even upon a periodic redetermination of "necessity," the Commission is statutorily authorized to issue a series of summary suspension orders based upon a single set of events or circumstances which threaten an orderly market. This question must, in our opinion, be answered in the negative.

The first and most salient point leading us to this conclusion is the language of the statute. Section 12(k) authorizes the Commission "summarily to suspend trading in any security . . . for a period not exceeding ten days . . . ." 15 U.S.C. § 78 l (k) (1976 ed.) (emphasis added). The Commission would have us read the underscored phrase as a limitation only upon the duration of a single suspension order. So read, the Commission could indefinitely suspend trading in a security without any hearing or other procedural safeguards as long as it redetermined every 10 days that suspension was required by the public interest and for the protection of investors. While perhaps not an impossible reading of the statute, we are persuaded it is not the most natural or logical one. The duration limitation rather appears on its face to be just that — a maximum time period for which trading can be suspended for any single set of circumstances.

Apart from the language of the statute, which we find persuasive in and of itself, there are other reasons to adopt this construction of the statute. In the first place, the power to summarily suspend trading in a security even for 10 days, without any notice, opportunity to be heard, or findings based upon a record, is an awesome power with a potentially devastating impact on the issuer, its shareholders, and other investors. A clear mandate from Congress, such as that found in § 12(k), is necessary to confer this power. No less clear a mandate can be expected from Congress to authorize the Commission to extend, virtually without limit, these periods of suspension. But we find no such unmistakable mandate in § 12(k). Indeed, if anything, that section points in the opposite direction.

Other sections of the statute reinforce the conclusion that in this area Congress considered summary restrictions to be somewhat drastic and properly used only for very brief periods of time. When explicitly longer term, though perhaps temporary, measures are to be taken against some person, company, or security, Congress invariably requires the Commission to give some sort of notice and opportunity to be heard. For example, § 12(j) of the Act authorizes the Commission, as it deems necessary for the protection of investors, to suspend the registration of a security for a period not exceeding 12 months if it makes certain findings " on the record after notice and opportunity for hearing . . . ." 15 U.S.C. § 78 l (j) (1976 ed.) (emphasis added). Another section of the Act empowers the Commission to suspend broker-dealer registration for a period not exceeding 12 months upon certain findings made only "on the record after notice and opportunity for hearing." § 78 o (b)(4) (1976 ed.) (emphasis added). Still another section allows the Commission, pending final determination whether a broker-dealer's registration should be revoked, to temporarily suspend that registration, but only "after notice and opportunity for hearing." § 78 o (b)(5) (1976 ed.) (emphasis added). Former § 15(b)(6), which dealt with the registration of broker-dealers, also lends support to the notion that as a general matter Congress meant to allow the Commission to take summary action only for the period specified in the statute when that action is based upon any single set of circumstances. That section allowed the Commission to summarily postpone the effective date of registration for 15 days, and then, after appropriate notice and opportunity for hearing, to continue that postponement pending final resolution of the matter. The section which replaced § 15(b)(6) even further underscores this general pattern. It requires the Commission to take some action — either granting the registration or instituting proceedings to determine whether registration should be denied — within 45 days. 15 U.S.C. § 78 o (b) (1) (1976 ed.). In light of the explicit congressional recognition in other sections of the Act, both past and present, that any long-term sanctions or any continuation of summary restrictions must be accompanied by notice and an opportunity for a hearing, it is difficult to read the silence in § 12(k) as an authorization for an extension of summary restrictions without such a hearing, as the Commission contends. The more plausible interpretation is that Congress did not intend the Commission to have the power to extend the length of suspensions under § 12(k) at all, much less to repeatedly extend such suspensions without any hearing.

B

The Commission advances four arguments in support of its position, none of which we find persuasive. It first argues that only its interpretation makes sense out of the statute. That is, if the Commission discovers a manipulative scheme and suspends trading for 10 days, surely it can suspend trading 30 days later upon the discovery of a second manipulative scheme. But if trading may be suspended a second time 30 days later upon the discovery of another manipulative scheme, it surely could be suspended only 10 days later if the discovery of the second scheme were made on the eve of the expiration of the first order. And, continues the Commission, since nothing on the face of the statute requires it to consider only evidence of new manipulative schemes when evaluating the public interest and the needs of investors, it must have the power to issue consecutive suspension orders even in the absence of a new or different manipulative scheme, as long as the public interest requires it.

This argument is unpersuasive, however, because the conclusion simply does not follow from the various premises. Even assuming the Commission can again suspend trading upon learning of another event which threatens the stability of the market, it simply does not follow that the Commission therefore must necessarily have the power to do so even in the absence of such a discovery. On its face and in the context of this statutory pattern, § 12(k) is more properly viewed as a device to allow the Commission to take emergency action for 10 days while it prepares to deploy its other remedies, such as a temporary restraining order, a preliminary or permanent injunction, or a suspension or revocation of the registration of a security. The Commission's argument would render unnecessary to a greater or lesser extent all of these other admittedly more cumbersome remedies which Congress has given to it.

Closely related to the Commission's first argument is its second — its construction furthers the statute's remedial purposes. Here the Commission merely asserts that it "has found that the remedial purposes of the statute require successive suspension of trading in particular securities, in order to maintain orderly and fair capital markets." Brief for Petitioner 37. Other powers granted the Commission are, in its opinion, simply insufficient to accomplish its purposes.

We likewise reject this argument. In the first place, the Commission has not made a very persuasive showing that other remedies are ineffective. It argues that injunctions and temporary restraining orders are insufficient because they take time and evidence to obtain and because they can be obtained only against wrongdoers and not necessarily as a stopgap measure in order to suspend trading simply until more information can be disseminated into the marketplace. The first of these alleged insufficiencies is no more than a reiteration of the familiar claim of many Government agencies that any semblance of an adversary proceeding will delay the imposition of the result which they believe desirable. It seems to us that Congress, in weighing the public interest against the burden imposed upon private parties, has concluded that 10 days is sufficient for gathering necessary evidence.

This very case belies the Commission's argument that injunctions cannot be sought in appropriate cases. At exactly the same time the Commission commenced the first series of suspension orders it also sought a civil injunction against CJL and certain of its principals, alleging violations of the registration and antifraud provisions of the Securities Act of 1933, violations of the antifraud and reporting provisions of the Securities Exchange Act of 1934, and various other improper practices, including the filing of false reports with the Commission and the dissemination of a series of press releases containing false and misleading information. App. 109. And during the second series of suspension orders, the Commission approved the filing of an action seeking an injunction against those in the management of CJL to prohibit them from engaging in further violations of the Acts. Id., at 101.

The second of these alleged insufficiencies is likewise less than overwhelming. Even assuming that it is proper to suspend trading simply in order to enhance the information in the marketplace, there is nothing to indicate that the Commission cannot simply reveal to the investing public at the end of 10 days the reasons which it thought justified the initial summary suspension and then let the investors make their own judgments.

Even assuming, however, that a totally satisfactory remedy — at least from the Commission's viewpoint — is not available in every instance in which the Commission would like such a remedy, we would not be inclined to read § 12(k) more broadly than its language and the statutory scheme reasonably permit. Indeed, the Commission's argument amounts to little more than the notion that § 12(k) ought to be a panacea for every type of problem which may beset the marketplace. This does not appear to be the first time the Commission has adopted this construction of the statute. As early as 1961 a recognized authority in this area of the law called attention to the fact that the Commission was gradually carrying over the summary suspension power granted in the predecessors of § 12(k) into other areas of its statutory authority and using it as a pendente lite power to keep in effect a suspension of trading pending final disposition of delisting proceedings. 2 L. Loss, Securities Regulation 854-855 (2d ed. 1961).

The author then questioned the propriety of extending the summary suspension power in that manner, id., at 854, and we think those same questions arise when the Commission argues that the summary suspension power should be available not only for the purposes clearly contemplated by § 12(k), but also as a solution to virtually any other problem which might occur in the marketplace. We do not think § 12(k) was meant to be such a cure-all. It provides the Commission with a powerful weapon for dealing with certain problems. But its time limit is clearly and precisely defined. It cannot be judicially or administratively extended simply by doubtful arguments as to the need for a greater duration of suspension orders than it allows. If extension of the summary suspension power is desirable, the proper source of that power is Congress. Cf. FMC v. Seatrain Lines, Inc., 411 U.S. 726, 744-745 (1973).

The Commission next argues that its interpretation of the statute — that the statute authorizes successive suspension orders — has been both consistent and longstanding, dating from 1944. It is thus entitled to great deference. See United States v. National Assn. of Securities Dealers, 422 U.S. 694, 719 (1975); Saxbe v. Bustos, 419 U.S. 65, 74 (1974).

While this undoubtedly is true as a general principle of law, it is not an argument of sufficient force in this case to overcome the clear contrary indications of the statute itself. In the first place it is not apparent from the record that on any of the occasions when a series of consecutive summary suspension orders was issued the Commission actually addressed in any detail the statutory authorization under which it took that action. As we said just this Term in Adamo Wrecking Co. v. United States, 434 U.S. 275, 287 n. 5 (1978):

"This lack of specific attention to the statutory authorization is especially important in light of this Court's pronouncement in Skidmore v. Swift Co., 323 U.S. 134, 140 (1944), that one factor to be considered in giving weight to an administrative ruling is `the thoroughness evident in its consideration, the validity of its reasoning, its consistency with earlier and later pronouncements, and all those factors which give it power to persuade, if lacking power to control.'"

To further paraphrase that opinion, since this Court can only speculate as to the Commission's reasons for reaching the conclusion that it did, the mere issuance of consecutive summary suspension orders, without a concomitant exegesis of the statutory authority for doing so, obviously lacks "power to persuade" as to the existence of such authority. Ibid. Nor does the existence of a prior administrative practice, even a well-explained one, relieve us of our responsibility to determine whether that practice is consistent with the agency's statutory authority.

"The construction put on a statute by the agency charged with administering it is entitled to deference by the courts, and ordinarily that construction will be affirmed if it has a `reasonable basis in law.' NLRB v. Hearst Publications, 322 U.S. 111, 131; Unemployment Commission v. Aragon, 329 U.S. 143, 153-154. But the courts are the final authorities on issues of statutory construction, FTC v. Colgate-Palmolive Co., 380 U.S. 374, 385, and `are not obliged to stand aside and rubber-stamp their affirmance of administrative decisions that they deem inconsistent with a statutory mandate or that frustrate the congressional policy underlying a statute.' NLRB v. Brown, 380 U.S. 278, 291." Volkswagenwerk v. FMC, 390 U.S. 261, 272 (1968).

And this is just such a case — the construction placed on the statute by the Commission, though of long standing, is, for the reasons given in Part III-A of this opinion, inconsistent with the statutory mandate. We explicitly contemplated just this situation in FMC v. Seatrain Lines, Inc., supra, at 745, where we said:

"But the Commission contends that since it is charged with administration of the statutory scheme, its construction of the statute over an extended period should be given great weight. . . . This proposition may, as a general matter, be conceded, although it must be tempered with the caveat that an agency may not bootstrap itself into an area in which it has no jurisdiction by repeatedly violating its statutory mandate."

And our clear duty in such a situation is to reject the administrative interpretation of the statute.

Finally, the Commission argues that for a variety of reasons Congress should be considered to have approved the Commission's construction of the statute as correct. Not only has Congress re-enacted the summary suspension power without disapproving the Commission's construction, but the Commission participated in the drafting of much of this legislation and on at least one occasion made its views known to Congress in Committee hearings. Furthermore, at least one Committee indicated on one occasion that it understood and approved of the Commission's practice. See Zuber v. Allen, 396 U.S. 168, 192 (1969); United States v. Correll, 389 U.S. 299, 305-306 (1967); Fribourg Navigation Co. v. Commissioner, 383 U.S. 272, 283 (1966).

While we of course recognize the validity of the general principle illustrated by the cases upon which the Commission relies, we do not believe it to be applicable here. In Zuber v. Allen, supra, at 192, the Court stated that a contemporaneous administrative construction of an agency's own enabling legislation "is only one input in the interpretational equation. Its impact carries most weight when the administrators participated in drafting and directly made known their views to Congress in committee hearings." Here the administrators, so far as we are advised, made no reference at all to their present construction of § 12(k) to the Congress which drafted the "enabling legislation" here in question — the Securities Exchange Act of 1934. They made known to at least one Committee their subsequent construction of that section 29 years later, at a time when the attention of the Committee and of the Congress was focused on issues not directly related to the one presently before the Court. Although the section in question was re-enacted in 1964, and while it appears that the Committee Report did recognize and approve of the Commission's practice, this is scarcely the sort of congressional approval referred to in Zuber, supra.

We are extremely hesitant to presume general congressional awareness of the Commission's construction based only upon a few isolated statements in the thousands of pages of legislative documents. That language in a Committee Report, without additional indication of more widespread congressional awareness, is simply not sufficient to invoke the presumption in a case such as this. For here its invocation would result in a construction of the statute which not only is at odds with the language of the section in question and the pattern of the statute taken as a whole, but also is extremely far reaching in terms of the virtually untrammeled and unreviewable power it would vest in a regulatory agency.

Even if we were willing to presume such general awareness on the part of Congress, we are not at all sure that such awareness at the time of re-enactment would be tantamount to amendment of what we conceive to be the rather plain meaning of the language of § 12(k). On this point the present case differs significantly from United States v. Correll, supra, at 304, where the Court took pains to point out in relying on a construction of a tax statute by the Commissioner of Internal Revenue that "to the extent that the words chosen by Congress cut in either direction, they tend to support rather than defeat the Commissioner's position . . . ."

Subsequent congressional pronouncements also cast doubt on whether the prior statements called to our attention can be taken at face value. When consolidating the former §§ 15(c) (5) and 19(a)(4) in 1975, see n. 1, supra, Congress also enacted § 12(j), which allows the Commission "to suspend for a period not exceeding twelve months, or to revoke the registration of a security, if the Commission finds, on the record after notice and opportunity for hearing, that the issuer of such security has failed to comply with any provision of this chapter or the rules and regulations thereunder." 15 U.S.C. § 78 l (j) (1976 ed.). While this particular power is not new, see 15 U.S.C. § 78s (a)(2), the effect of its exercise was expanded to include a suspension of trading. "With this change," stated the Senate Committee on Banking, Housing and Urban Affairs, "the Commission is expected to use this section rather than its ten-day suspension power, in cases of extended duration." S. Rep. No. 94-75, p. 106 (1975) (emphasis added). Thus, even assuming, arguendo, that the 1963 statements have more force than we are willing to attribute to them, and that, as the Commission argues, § 12(j) does not cover quite as broad a range of situations as § 12(k), the 1975 congressional statements would still have to be read as seriously undermining the continued validity of the 1963 statements as a basis upon which to adopt the Commission's construction of the statute.

In sum, had Congress intended the Commission to have the power to summarily suspend trading virtually indefinitely we expect that it could and would have authorized it more clearly than it did in § 12(k). The sweeping nature of that power supports this expectation. The absence of any truly persuasive legislative history to support the Commission's view, and the entire statutory scheme suggesting that in fact the Commission is not so empowered, reinforce our conclusion that the Court of Appeals was correct in concluding no such power exists. Accordingly, its judgment is

Affirmed.