This appeal presents another example of the burgeoning impact of the federal securities laws on the courts. Paul S. Dopp, the largest individual shareholder of Butler Aviation International, Inc.,1 has used § 10(b) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder as a wedge to block the sale of 51,500 shares of Butler stock pledged by him to Franklin National Bank as collateral for a loan of $380,000. Ordinarily, this action, which involves little more than a dispute between a debt- or and creditor over the disposition of collateral upon default, would be grounded on alleged violations of state commercial or contract law. But Dopp, asserting that Franklin had misrepresented to him that he would have a right of first refusal on any sale arranged by Franklin and that Franklin failed to disclose that it was negotiating for the sale of shares, obtained a preliminary injunction from Judge Brieant restraining Franklin from honoring an option to purchase the shares which Franklin had granted to John and Michael Galesi. Judge Brie-ant granted this preliminary injunction without holding any evidentiary hearing, relying solely on the affidavits and depositions submitted by the parties.2 Franklin has appealed. We cannot agree with Judge Brieant that Dopp established a likelihood of success on the merits of his 10b-5 claim or that he will suffer irreparable injury if the shares are sold pursuant to the option agreement. Accordingly, we reverse. This result, contrary to the implications of the dissenting opinion, in no way turns upon our views of plaintiff’s wisdom in pursuing his claims under the federal securities laws.3 We rely solely on established principles of equitable remedies and standards of appellate review. Our extended discussion, due in no small measure to the broadside attack by our dissenting brother, should not indicate that we consider this a novel case or, *876indeed, one where the result was ever in doubt.
The facts, which present the intriguing story of a shareholder fighting foreclosure so that he could retain leverage in a proxy contest, are essential to this appeal which hinges in the final analysis on the weighing of equities.4 On July 17, 1969, Dopp borrowed $380,000 from Franklin, executing a demand promissory note secured by a pledge of 51,500 shares of Butler common stock.5 At that time (and until January, 1971) Dopp was the President and Chairman of the Board of Butler, a Delaware corporation whose stock is traded on the American Stock Exchange. The promissory note, which included the pledge agreement, provided that upon any default of the borrower the bank could “forthwith sell, assign, give option or options to purchase, and deliver any and all securities” pledged as collateral. The note further provided that “no waiver whatsoever [of the bank’s rights] shall be valid unless in writing, signed by the Bank, and then only to the extent therein set forth.”
By July, 1970,- although Franklin had been pressing for repayment, Dopp still owed $351,000 in unpaid principal. On July 14 Dopp presented a plan whereby he would repay Franklin in full by August 15 out of the proceeds of a $2,500,-000 advance he expected from a Swiss company. But, not untypical of the many promises he would make to Franklin, Dopp did not meet this self-imposed deadline. At this point, Franklin transferred collection responsibility from its commercial loan department to its euphemistically termed “salvage” department, and when Dopp made only a few small partial payments in the ensuing months,6 Franklin secured a default judgment against Dopp on December 16, 1970, for $369,447.61. •
The very next day Dopp and Franklin entered into negotiations which ultimately resulted in a written stipulation, signed by both parties on January 20, 1971, providing that Dopp would have until February 26 to pay Franklin the reduced sum of $325,045.25 plus interest at the rate of 7%% from the date of judgment. If the stipulated amount was not repaid, the judgment was to become immediately enforceable. In return, Dopp executed as additional security second mortgages on two Pepsi-Cola bottling plants he owned in Michigan.7 But once again Dopp failed to meet his obligation and by May 14, 1971, he had made only sporadic payments totaling $20,000.
In late May, after G. Norman Wid-mark, the new Chairman of Butler, informed Franklin that Dopp’s shares were no longer control stock, Franklin decided to sell the 51,500 shares. Bruce Sutherland, the Franklin vice-president who had been overseeing the Dopp account, began negotiating with John and Michael Galesi.8 The Galesis apparently were friends of Widmark and had made investments with him on previous occasions. On June 15, 1971, Franklin gave Dopp formal written notice that it in*877tended to sell the shares at a private sale on or after June 25.
Just as he was spurred to action by the default judgment entered the previous December, Dopp again sought to buy time from Franklin. Accordingly, on June 28 he and Sutherland reached an oral agreement whereby Franklin would not sell the Butler shares if Dopp made a $20,000 payment in four days (July 2), delivered an additional 10,000 shares of Butler stock as collateral and made arrangements for the sale of all the Butler shares by July 21. Although Dopp paid the $20,000 (but not until July 26 instead of July 2), he never posted the additional collateral, nor did he make any arrangements for the sale of the 51,500 shares.9
The foregoing facts are virtually undisputed. The factual dispute with which we are concerned and which is the crux of this action grows out of an August, 1971, telephone call. After hearing from an obviously misinformed source that Franklin actually had sold the shares, Dopp immediately telephoned Sutherland, who assured him that this was not the case. Dopp claims, however, and so stated in his deposition, that Sutherland also gave him oral assurance that before Franklin sold the shares, it would give him the opportunity to produce a third person of his choice who would be ready to purchase on the same terms available to Franklin for the disposition of the stock, or, in the alternative, it would permit him to redeem the shares himself at the same price. He admits that Sutherland did not agree to any time period within which he would have to exercise this alleged right of first refusal, but says that he assumed “it would be a reasonable period of time, at least a few hours . . . . ” Sutherland vehemently disputes any such agreement. Indeed, he testified in his deposition:
“Q. I don’t understand. Nowhere in these entries [in Franklin’s Credit File] is it stated that Mr. Dopp told you in the event you were going to sell the shares he would arrange for the purchase.
Now, just show me where it says that. A. It doesn’t say that in here because I never agreed to anything like that.”
In the meantime, negotiations between Franklin and the Galesis continued, culminating in a written option agreement dated September 21,10 One week later Franklin advised Dopp of this agreement, but did not disclose the names of the third parties. (Sutherland, on instructions from the Galesis, never had informed Dopp that he was negotiating with them.) Dopp instituted this action in the Southern District of New York on October 12, against Franklin, the Galesis, Widmark and Butler, primarily seeking rescission of the option agreement and an unspecified amount of damages. As his brief before this Court characterizes it, the amended complaint asserts essentially three claims: that Franklin’s misrepresentation concerning his right of first refusal and its failure to disclose that it was negotiating with the Galesis violated § 10(b) of the Securities Exchange Act and Rule 10b-5; that the option agreement violated § 7 of the Securities Exchange Act and Regulation U thereunder which establishes margin requirements; and that Franklin, in entering into the option agreement, did not act in a “commercially rea*878sonable” manner in violation of § 9-504 of the Uniform Commercial Code.11
On October 18 Dopp moved for a preliminary injunction, alleging that he would be irreparably injured if the sale to the Galesis were consummated because he was involved in a proxy fight with Butler management and the share “could mean the difference between victory and defeat.” Judge Brieant, although he did not hold an evidentiary hearing, found that “plaintiff shows reasonable probability of success” on his securities claim and that he would suffer irreparable injury because the block of Butler stock is “unique” and has “no ascertainable market value.” Accordingly, he issued his preliminary injunction on November 19.12
I.
It is axiomatic that because a preliminary injunction is a drastic remedy, it will not be granted unless the plaintiff can make a clear showing of probable success. See, e. g., Intercontinental Container Transport Corp. v. New York Shipping Ass’n, 426 F.2d 884, 887 (2d Cir. 1970); Checker Motors Corp. v. Chrysler Corp., 405 F.2d 319, 323 (2d Cir.), cert. denied, 394 U.S. 999, 89 S.Ct. 1595, 22 L.Ed.2d 777 (1969). On the record as we review it, Judge Brieant was not justified in concluding that Dopp made the requisite showing of probable success.13
Before considering the basis for this conclusion, we refer briefly to our *879role as a reviewing court. Our dissenting brother is quick to point out that the district judge’s findings “are not to be disturbed unless found to be clearly erroneous.” This is not a case, however, where there was an evidentiary hearing below and the credibility of witnesses played an essential part in the district judge’s determinations. We are in as good a position as the district judge to read and interpret the pleadings, affidavits and depositions and thus have broader discretion on review. See Concord Fabrics, Inc. v. Marcus Brothers Textile Corp., 409 F.2d 1315, 1317 (2d Cir. 1969).
The linchpin of Dopp’s argument is the alleged oral agreement granting him a right of first refusal.14 In order to grant the preliminary injunction, the district judge must have assumed implicitly that Dopp would prevail in his unsupported claim that Sutherland entered into the agreement during the August telephone call. To do so, he had to reject Sutherland’s claim, equally as strong, to the contrary. Generally, of course, a judge should not resolve a factual dispute on affidavits or depositions, for then he is merely showing a preference for “one piece of paper to another.” Sims v. Greene, 161 F.2d 87, 88 (3d Cir. 1947). This is particularly so when the judge, without holding an evidentiary hearing, resolves the bitterly disputed facts in favor of the party who has the burden of establishing his right to preliminary relief. See id.; 7 Moore, Federal Practice § 65.04 [3]. This caveat is most compelling “where everything turns on what happened and that is in sharp dispute; in such instances, the inappropriateness of proceeding on affidavits attains its maximum . . . ” Securities and Exchange Comm’n v. Frank, 388 F.2d 486, 491 (2d 1968) (Friendly, C. J.). In this case, where all stands or falls on Dopp’s claim, denied by Sutherland, that an oral agreement was made in August giving him a right of first refusal, an evidentiary hearing was essential to resolve the credibility gap.
Dopp maintains, however, that Franklin waived its right to a hearing because it did not insist on one. It is true that we have held that a defendant who joins “the battle of affidavits with as much relish as the [plaintiff] ” should not be heard to complain when the decision is adverse. Semmes Motors, Inc. v. Ford Motor Co., 429 F.2d 1197, 1205 (2d Cir. 1970). We reaffirm that principle here, but even where a party can be deemed to have waived his right to a hearing, the movant is not relieved of his burden of establishing a reliable factual basis for the preliminary injunction. 7 Moore, Federal Practice ft 65.04 [3], at 1641. Certainly, it could not be suggested that the parties could waive their right to a decision according to law and confer upon the district judge the power to decide by a toss of the coin. Unfortunately, Judge Brieant did not articulate any reasons for concluding that the victory belonged to Dopp; nor do we believe that he could have.15
In light of what we have stated, it is appropriate that we revert to our observation early in this opinion. Dopp’s promissory note provided that Franklin *880would not be deemed to waive any of its rights, unless the waiver were in writing and signed by Franklin. Moreover, § 8-319 of the Uniform Commercial Code provides that a contract for the sale of securities is not enforceable unless it is in writing or there is a written memorandum by the party against whom it is to be enforced. Under these circumstances it is difficult to believe that Dopp, obviously an experienced investor and knowledgeable in the area of commercial transactions, would not have demanded that the crucial agreement upon which he relies, if there was one, be reduced to writing. The “agreement” is also cast in a cloud by Dopp’s admission that he and Sutherland had not agreed on the time period within which Dopp could exercise the alleged right. Finally, Franklin’s credit file with regard to Dopp’s account, which meticulously lists all other agreements and transactions, does not make a single reference to the alleged agreement. Thus, if we were forced to reach any conclusion on the basis of the scanty record before us, we would be compelled to hold that Dopp failed to carry his burden on his application.
But, even if we were to assume that the parties had reached the oral agreement, we could not conclude on this record that Dopp made a showing before Judge Brieant, by clear and convincing facts, that he in all likelihood will prevail in establishing the elements of his 10b-5 claim. To succeed in a 10b-5 action, the plaintiff must prove that he relied upon a misrepresentation of a material fact to his detriment. See, e. g., List v. Fashion Park, Inc., 340 F.2d 457 (2d Cir.), cert. denied, 382 U.S. 811, 86 S.Ct. 23, 15 L.Ed.2d 60 (1965). Thus, Dopp will have to establish that, but for the misrepresentation, he would have acted differently — in this case, that he would have redeemed the shares himself or found a third party to purchase .them if he had been given the opportunity.16 We know, however, that as late as July, Dopp had not done either.17
Nor are we prepared on this record to conclude that Dopp will be able to show that the alleged misrepresentation was material. As we stated in List, 340 F.2d at 462:
The basic test of “materiality,” on the other hand, is whether “a reasonable man would attach importance [to the fact misrepresented] in determining his choice of action in the transaction in question.” Restatement, Torts § 538(2) (a); accord, Prosser, Torts 554-55; I Harper & James, Torts 565-66. Thus, to the requirement that the individual plaintiff must have acted upon the fact misrepresented, is added the parallel requirement that a reasonable man would also have acted upon the fact misrepresented.
In the face of the provision of the promissory note that all waivers by Franklin had to be in writing, it strains credulity that Dopp could have relied reasonably on the alleged oral agreement, or in terms of 10b-5, that any misrepresentation was material to his course of action.18
*881We reiterate here that we conclude only that Dopp has not shown, on the record before us on this appeal, that he likely will succeed on the merits below. This is not to say that we might not reach a different conclusion when presented with a full record after trial.
II.
As with every rule we believe to be hard-and-fast, including those we consider elementary, exceptions occasionally are cut out. We are told that if there is an imbalance of hardships and the equities weigh heavily in favor of the movant, an injunction will issue to maintain the status quo pendente lite if “the plaintiff has raised questions going to the merits so serious, substantial, difficult and doubtful, as to make them a fair ground for litigation and thus for more deliberate investigation.” Hamilton Watch Co. v. Benrus Watch Co., 206 F.2d 738, 740 (2d Cir. 1953). See also Semmes Motors, Inc., 429 F.2d at 1204-1207. Dopp invokes this doctrine to support the decision below. Although we do not question Judge Brieant’s conclusion that Franklin will not suffer irreparable injury,19 we cannot agree that Dopp’s plight will differ materially from Franklin’s if the injunction is dissolved.
In this connection, the district judge concluded that the Butler stock was “unique” because Franklin could not sell it in a block on the open market without severely depressing the market price. As a general proposition, shares traded on the open market are considered to have an ascertainable market value. See, e. g., Simon v. Electrospace Corp., 28 N.Y.2d 136, 145-146, 320 N.Y.S.2d 225, 269 N.E.2d 21 (1971); 5A Corbin, Contracts § 1148. Although a purchase of 51,500 shares at this time or in the near future undoubtedly would require an outlay substantially in excess of the option price of $281,000, Franklin, if it has committed any Securities Exchange Act or state law violation, will be able to respond in damages. Moreover, Dopp has not shown that he could not purchase an additional 51,500 shares on the open market or in a private transaction20 if he eventually is the successful party. If would appear, therefore, that Dopp’s inability to prove irreparable injury21 is *882in itself sufficient grounds for reversing the grant of the preliminary injunction. See Foundry Services, Inc. v. Beneflux Corp., 206 F.2d 214, 216 (2d Cir. 1953).
For the reasons stated, the order of the district court is reversed, the preliminary injunction is vacated, and this case is remanded for further proceedings. In view of our disposition, it is suggested that the trial on the merits be expedited.
. Dopp is the beneficial owner of over 190,000 shares of Butler, or more than 18% of the stock outstanding. All but approximately 20,000 shares have been pledged as collateral.
. Dopp previously had obtained a temporary restraining order from Judge Gur-fein.
. Our dissenting brother apparently fears that we would undermine the Supreme Court’s decision in Superintendent of Insurance v. Bankers Life & Casualty Co., 404 U.S. 6, 92 S.Ct. 165, 30 L.Ed.2d 128 (1971), before the ink is dry. Suffice it to say, we do not suggest that the preliminary injunction should not have issued because Dopp failed to state a claim upon which relief could have been granted. Certainly our dissenting brother would not suggest that Justice Douglas’s warning in Bankers Life that “Section 10(b) must be read flexibly, not technically and restrictively” relieves a plaintiff who is seeking either preliminary or permanent relief of his traditional burden of proof.
. Our dissenting brother dwells at length on the conspiratorial aspects of the complaint — i. e., the allegations that Franklin conspired with Widmark, the Galesis and Butler to deprive Dopp of his Butler shares. He uses “conspiracy” to suggest some sort of “dirty business”. It reminds us of the prosecutor who adds a conspiracy count to “strengthen” an otherwise weak case. See Harrison v. United States, 7 F.2d 259, 263 (1925) (L. Hand, J.: “Conspiracy, that darling of the modern prosecutor’s nursery.”). It is of interest that the district judge did not rely on any so-called “conspiracy.”
. The loan was one of a series of loans for more than $1,190,000.
. Dopp’s check of October 29, 1970, in the amount of $10,000 was returned on initial presentment because of insufficient funds.
. There is some dispute as to whether Dopp also agreed to give Franklin a mortgage on liis yacht.
. Sutherland previously had determined that the shares could not be sold in large blocks on the open market without breaking the “thin” market for Butler stock. He also decided as a matter of policy that it was too risky to sell the stock on the open market over an extended period of time.
. The dissenting opinion stresses Dopp’s continuing partial payments, while it conveniently underplays his repeated failures to meet his obligations.
. The Galesis were granted a 60-day option to purchase the shares for $281,000 (approximately $5.45 per share), payable as follows: $17,500 paid immediately, $32,500 paid upon exercise of the option, and $231,000 plus interest paid over a period of five years. Dopp’s account was to be credited with the entire amount, and the $17,500 was to be retained irrespective of whether the option was exercised.
. The amended complaint differed from the original complaint primarily in that it added Franklin’s failure to disclose information about negotiations with the Galesis as another basis for his securities law claim and the separate state law claim under the Uniform Commercial Code. Dopp claims that he did not know of Franklin’s failure to disclose until Sutherland was deposed.
. On the same day, the Galesis exercised their option to purchase the shares at $5.45 per share, although the shares were then selling at $4.75 per share on the American Stock Exchange. We have been informed that the transfer will be consummated if the injunction is dissolved. Butler stock is now selling at approximately $12 per share.
. We assume for purposes of this appeal, but do not decide, that Dopp has standing to assert a claim under Rule 10b-5 as the beneficial owner of the pledged shares. Whether a debtor who pledges stock to secure a loan retains an interest sufficient to classify him as “seller” even after he has defaulted in repayment of the loan and a court judgment has been obtained against him is a difficult question. Similarly, whether Dopp’s allegation that he had been promised a right of first refusal for the stock might give him standing as an “aborted purchaser” has not been considered upon tliis appeal. These questions remain open for consideration by the district, court.
Dopp argued before this court that he was likely to succeed on both his claim under § 7 of the Securities Exchange Act of 1934 and Regulation U promulgated thereunder and his claim under the Uniform Commercial Code. Judge Brie-ant did not base his decision on either ground, and neither of the claims can withstand scrutiny at this stage of the proceedings. Although Regulation U at the time the option was granted imposed a margin limitation of 35%, 12 C.F.R. § 221.3 (i) provides that the regulation shall not prevent “a bank from taking such actions as it shall deem necessary in good faith for its own protection.” There is no evidence that Franklin was not acting in this manner. Moreover, there is some doubt that Dopp, who was not the purchaser under the option, has standing to assert a violation of Regulation U. Compare, e. g., Natkin v. Exchange National Bank of Chicago, 342 F.2d 675 (7th Cir. 1965).
Section 9-504 of the Uniform Commercial Code requires a secured party, if he is going to foreclose on collateral, to dispose of the collateral in a “commercially reasonable” manner. Although Judge Brieant stated that he found on the whole record “at least some suggestion to the effect that defendant Franklin is not acting in a ‘commercially reasonable’ manner,” he did not indicate on which part of the record he relied, and we cannot find any evidence to support the alleged violation of § 9-504. Franklin gave notice of the intended private sale as required by the Code, § 9-504(3), and there is no allegation that the collateral was sold for less than its true value.
We emphasize, however, that Dopp on remand is free to introduce evidence to establish any of the claims asserted in his complaint, and that our statements re*879garding his likelihood of success on the merits based solely on the scanty record now before us should not deter a fresh and complete appraisal after hearing witnesses and a full trial on the merits.
. Dopp also alleges that Franklin failed to disclose that it was negotiating with the Galesis. Unless there was an agreement granting Dopp a right of first refusal, we do not see how this nondisclosure could have injured him. Moreover, Dopp admitted in his deposition that he knew that Franklin was negotiating for the sale of the securities and that he suspected the Galesis were the third parties.
. Findings are not a jurisdictional requirement of appeal, but merely aid the appellate court in reviewing the decision below. In certain cases, however, the absence of findings can so obscure the basis for granting the relief below that reversal is called for on this ground alone. See SEC v. Frank, supra, 388 F.2d at 493.
. Dopp also claims that he relied on the misrepresentation in continuing partial payments of the principal due. One does not rely on a representation to his detriment, however, in performing a legal obligation. See Ryan v. J. Walter Thompson Co., 453 F.2d 444 (2d Cir. 1971); Williston, Contracts § 1515, at 477 (3d ed. 1970).
. The affidavit of Herman Anstatt, sworn to on November 1, two days before argument of the motion, does not convince us otherwise. Although Mr. Anstatt stated that he would have been willing on September 21 to purchase the shares on the same terms offered to the Galesis, he never gave Franklin a firm, irrevocable offer or tendered the purchase price. Moreover, there is no evidence that Dopp could have unearthed Mr. Anstatt on short notice during August. As it was, Mr. An-statt’s affidavit was not submitted for more than 10 days after Dopp’s motion for the preliminary injunction.
. There is the further question whether the misrepresentation has caused any in*881jury. We have been presented with a substantial dispute, involving technical considerations of New York contract law, concerning the enforceability of the alleged oral argeement. If Dopp never could have exercised a right of first refusal even had he known of the impending option agreement with the Galesis, presumably he can show no damage. It would serve no purpose at this stage, however, to embark on a long exposition and analysis of New York law.
. The price of Butler stock approximately has doubled since the date of the option agreement. If the 51,500 shares, now worth in the neighborhood of a half million dollars are not sufficient to protect Franklin against Dopp’s debt (slightly more than $300,000), Franklin can protect itself through the second mortgages on the Pepsi-Cola bottling plants, which were pledged as additional collateral in January, 1971.
. Apparently Dopp was able to acquire 55,000 shares in private transactions between April and June 1971. Committee for New Management of Butler Aviation v. Widmark, 335 F.Supp. 146, 154 (E.D.N.Y.1971).
. Dopp, of course, did not allege that lie would not be able to purchase another 51,500 shares, but rather that the shares pledged to Franklin were essential to an impending proxy contest. Judge Brieant concluded that “it is difficult to conceive how a person against whom such a substantial unpaid judgment is outstanding, may successfully conduct a proxy contest for control of a publicly held corporation.” AVe see no reason to disturb this conclusion, particularly in view of Dopp’s subsequent defeat by more than 300,000 shares at the Butler election on December 14, 1971. Our dissenting brother argues that a bare assertion that 250,000 votes were challenged by Dopp should be sufficient to carry the day on the issue of irreparable injury. We assume, however, that if the challenges could have changed the outcome of the election, they would have been resolved.
Dopp also informed us on appeal that he might well “seek to oust this management [Widmark] at the next Butler *882shareholder meeting” which was scheduled for May 1972. Since the injunction was in effect throughout May, our decision cannot affect his effort.