dissenting.
Plaintiffs alleged that defendants, five Chicago banks, violated sections 1 and 2 of the Sherman Act, 15 U.S.C. §§ 1, 2, by conspiring between themselves and with *470their correspondent banks to fix the interest rates they charged as member banks of the Midwest Bank Card System, Inc., and its successor, the Interbank-Master Charge System, Inc. (“Mastercharge”). The district court entered summary judgments for all defendants on all counts.1 I would affirm the summary judgments for defendants Continental, Harris and Central as to the charges of a vertical conspiracy with their respective correspondents. I would reverse the summary judgment granted to defendants Continental, Harris, Central and Pullman on the horizontal conspiracy.
I. THE STANDARD OF REVIEW
The issue before this court is whether this court is satisfied that a properly instructed jury, giving full weight to plaintiffs’ evidence, drawing every reasonable inference in its favor, and subjecting defendants’ evidence to a critical eye, could not rationally find that plaintiffs were entitled to any relief. Ambook Enterprises v. Time, Inc., 612 F.2d 604, 611 (2d Cir. 1979), cert. dismissed, - U.S. -, 101 S.Ct. 35, 65 L.Ed.2d 1179 (1980). See Continental Co. v. Union Carbide & Carbon Corp., 370 U.S. 690, 696, 82 S.Ct. 1404, 1409, 8 L.Ed.2d 777 (1962).2 That the issues may be particularly difficult for jury consideration is immaterial to the merits of plaintiffs’ claim. The court should only consider whether, after examining all the evidence, plaintiffs’ case remains devoid “of any significant probafive evidence tending to support the complaint.” Ambook Enterprises v. Time, Inc., supra, 612 F.2d at 611, citing First National Bank of Arizona v. Cities Service Co., 391 U.S. 253, 290, 88 S.Ct. 1575, 1593, 20 L.Ed.2d 569 (1968).
II. THE HORIZONTAL CONSPIRACY A.
As the majority and the district court noted, the circumstances surrounding the formation of Midwest in 1966 and its successor, Mastercharge, are not in dispute. Weit I, 467 F.Supp. at 199. The significance of plaintiffs’ evidence introduced in support of their allegations of a horizontal conspiracy is more readily apparent, however, when viewed in light of certain salient facts about the Chicago banking community and the credit card industry at the time of Midwest’s formation. Plaintiffs produced evidence to show the following.
In 1966, the Chicago banking market was an oligopoly dominated by First National Bank3 and Continental.4 Illinois prohibitions against branch banking5 contributed to this high level of concentration.6 Defendants’ officers knew each other personally, attended many of the same functions, and were members of the same clubs. Weit 1,467 F.Supp. at 206-07. Kenneth Zweiner, chairman of Harris, and Tilden Cummings, of Continental, worked together for 20 years as trustees of Northwestern Universit*471y.7 David Kennedy, chairman of Continental, and Frank Bauder, president of Central, knew each other “very well” because Bauder had worked with Kennedy at Continental.8 James R. Kennedy, who ran the Town and Country Charge Card Program at Continental,9 became American’s second vice-president in charge of the bank’s charge card operations, which he designed, instituted and managed.10 Thus, the very nature of the Chicago banking community facilitated the exchange of pricing information. Gainesville Utilities Dep’t v. Florida Power & Light Co., 573 F.2d 292, 303 (5th Cir.), cert. denied, 439 U.S. 966, 99 S.Ct. 454, 58 L.Ed.2d 424 (1978). Given this situation, defendants’ conduct should be carefully scrutinized for evidence of conspiratorial behavior. Id.
Illinois had no credit card interest law in 1966. The Illinois usury statute in effect at that time, however, prohibited interest rates in excess of a 7% add-on per annum, (which Harris counsel said would proximate 14% annually), Ill.Ann.Stat. ch. 74, § 4 (Smith-Hurd 1966), and defendant Harris, a state bank, assumed that it would be bound by this statute. See Plaintiffs’ Ex. 1, quoted in Weit I, 467 F.Supp. at 200. The federal statute governing the nationally chartered banks (defendants Continental and Central, and First) provided that they could charge interest at the rate allowed by the laws of the state in which the bank is located. 12 U.S.C. § 85 (1976). In determining what state law it was bound by, defendant Continental looked to the Illinois Consumer Finance Act, Ill.Ann.Stat. ch. 74, § 19 et seq. (Smith-Hurd 1966), which applied to small consumer loans and allowed an interest rate of 3% per month on loans up to $150.00, or 36% per annum, 2% per month or 24% per annum on the balance of the loans exceeding $150 and not exceeding $300, and 1% per month, or 12% per annum, on any part of the unpaid balance exceeding $300. Id. at § 31. Continental interpreted this Act as allowing a Pk% per month, or 18% per annum maximum overall effective rate. Weit I, 467 F.Supp. at 201. Without attempting to resolve these seemingly conflicting positions, I assume throughout this opinion that the limitations on the two types of banks differed as the parties thought.
Defendant banks began discussing the idea of a joint charge card in 1966 so as to prevent competition from outsiders and to prevent any one Chicago bank from taking the lead in the new charge card market. Continental was afraid that outsiders would enter the market, resulting in chaos.11 Continental believed that First’s motive in proposing a joint system was to prevent Continental from getting a head start.12 At the same time, Continental didn’t want First, Harris and Central to start a charge card system “while we were sitting over there without a charge card.”13 High start-up costs and large initial losses were projected, Weit I, 467 F.Supp. at 201, so defendants were anxious to avoid an outbreak of competition. Gaylord Freeman, president and later chairman of First testified “... since nobody had a viable credit card [in 1966] and it was all new and if one of the others had aggressively merchandised the card at a lower cardholder interest rate, I think [First] would have to go too, at the lower rate, too.” Id. at 207.
In the spring of 1966, then, when the subject of bank credit cards was “... in the *472air,” 14 First hosted a meeting attended by representatives of Continental, Harris and Northern Trust15 to discuss the feasibility of a credit card program. The notes of this meeting, held on May 22,1966, summarize a discussion about the maximum legal interest rate:
Lewis [of Harris, a state bank] commented that the maximum must be no more than the equivalent of 7% add-on per annum, or less than 14%. Foote [of Harris], who said he had looked into credit cards on his own for Harris some months ago, found specific revolving credit enabling legislation in other states where 1%% per month is in effect. Wood [of First] commented that this is troubling First’s lawyers, too.
Plaintiffs’ Ex. 1, quoted in Weit I, 467 F.Supp. at 200. Representatives of the four banks met again on May 26, 1966. The minutes of this meeting state that “Wood [of First] said the First’s lawyers had two legal questions — rate and anti-trust — and the anti-trust seemed to be the easier of the two.” Id. The group began meeting regularly after this. American was not a formal participant, but sent a representative. Central, a correspondent bank of both Harris and Continental, did not participate in these early meetings, but received status reports on the formation of a compatible system.16 Pullman, a correspondent of First, Continental and Harris, did not attend the group meetings either, as it was planning to issue its own bank credit card. Pullman received mailings about the compatible system, however, and in June, a Continental officer called .a Pullman officer to tell him about a pending Continental press release on the joint system. Weit II, 478 F.Supp. at 289.
During these early meetings, the group determined that card design, imprints and forms would be uniform, and that a participating merchant directory, a list of can-celled or stolen cards, and a merchant instruction booklet would be jointly issued. Weit I, supra at 200. They also agreed that their correspondent banks could retain their relationship with local merchants in return for soliciting card holders. Id. at 203. Without this latter agreement, the four banks would have solicited correspondents’ customers directly, provoking the correspondents into forming their own bank credit card systems, thereby diluting the market. Id.
In late June, 1966, officers of First, Continental, Harris and Northern flew to San. Francisco to consult with the Wells Fargo Bank about the Western States Bank Card Association.17 The next day, these officers met with the president of Bank Americard Service Corporation to discuss Bank Americard’s revenues and expenses, including the “regular 1V2% per month” interest charge.18
In July, 1966, the four banks retained Information Sciences Associates, a consulting firm with experience in the formation of charge card systems. Id. at 200. Later that month, Continental personnel received a memorandum dated July 25, 1966 from Miles G. Seeley, senior partner of Mayer, Brown & Platt, counsel for Continental, limiting discussions with other banks to the subject of planning a compatible card system and specifically forbidding any “discussion (even in jest)” of “... [f]ees, discounts, billing and extended credit terms or any other economic terms of the relationship between any bank and its own credit cardholders.” 19 The four banks employed Mayer, Brown & Platt to advise them on antitrust matters, and the Seeley memorandum was distributed to other defendant banks. *473From this point on, counsel monitored the meetings of defendants’ “study group” to ensure anti-trust compliance.20
During this time, defendant Pullman was going ahead with plans to issue its own charge card. Pullman intended to announce its card, which was to have an interest rate of 18% per annum, on August 12, 1966, and the program was to begin on November 7, 1966. Weit II, 478 F.Supp. at 288-90. The other banks knew about Pullman’s plans. A description of the Pullman credit card program, including the cardholder interest rate, appeared in the feasibility study prepared by Continental in July, 1966,21 and on August 5, 1966, at a meeting of the Continental Advisory Committee, Alfred Lindgren of Continental reported “that the Pullman Bank has changed their package, and are now offering basically what we are proposing.”22 The night before Pullman’s scheduled announcement, three Continental officers had dinner with Donald O’Toole, president of Pullman, and tried to talk him into delaying Pullman’s start-up date. Id. at 289. O’Toole refused. Continental, Harris and First then decided to advance their start-up dates to early November.23
On September 8, 1966, Continental announced its plans for an all purpose charge card.24 Harris announced its entry into the charge card business the next day,25 and First made its announcement the following week.26 All three banks stated that they would be part of a compatible charge card system, and that they would issue their cards in November. None of the announcements mentioned interest rates to be charged future cardholders. At the same time, Northern announced it was dropping out of the program.27
Continental, Harris and First continued to inform Pullman of their plans. Finally, in the fall of 1966, Pullman joined the group. Id. at 289-90. Mr. Murphy, a Pullman officer who became president of Midwest in 1967, testified that Pullman joined Midwest “[bjecause we were concerned ... that we were going to have competing bank card systems. ... And also, that we were a failure.” Id.
Central decided to join the group at this time as well. Although it had not participated in or sent a representative to the formal study group meetings, a Central vice-president had attended a presentation on interbank charge card transfers held in late August. Id. at 288. Central also knew of Pullman’s plans. Id. Central officers assumed they would charge the maximum legal interest rate, which their counsel had advised was 18% per annum, or l'A% per month. Id.
On October 24, 1966, First, Continental, Harris, Central and Pullman signed the “interim agreement” establishing the Midwest charge card system. Weit I, 467 F.Supp. at 202. The agreement mandated certain requirements for all membership banks: uniform floor limits; uniform cash advance limits; uniform merchandising return procedures; uniform advertising limitations; uniform transaction reporting procedures; and uniform card format and design. Id. It did not mention charge card holder interest rates. By this time, however, each defendant, with the exception of American28 was planning on charging its cardholders an interest rate of 18% per annum, or 1%% per month. Continental, which thought it was bound by the Illinois Consumer Finance Act, could have charged an interest rate of *47436% per annum for the first $150, 24% on the next $150, and 12% on the remaining balance above $300,29 but settled on an interest rate of 18% per annum, as did Central, which decided 18% was the maximum allowed by law. Weit II, 478 F.Supp. at 288. Harris, which assumed it was limited by the Illinois usury law30 to charging a 7% add-on, or less than 14% annually, Weit I, 467 F.Supp. at 200, arrived at the 18% interest rate by charging 1% interest and Vfe% “service charge” per month.31 Pullman was also charging an interest rate of 18%.
When the Illinois General Assembly convened in 1967, the Midwest group hired William Dillon, a lawyer and professional lobbyist, to lobby for a credit card interest bill and represent the banks before the Illinois legislature.32 An early draft of the Midwest bill set the maximum cardholder interest rate at 24%,33 but later drafts settled on 18%.34 Midwest paid Dillon for his efforts, even though Dillon thought the bill was unnecessary for the national banks.35 The legislature passed the Midwest bill which went into effect on July 24, 196736 eight months after the banks first issued their cards at the uniform rate of 18% per annum.
Although American had attended the Midwest organizational meetings in 1966, it did not get into the charge card business until 1968. It then hired James Kennedy, who ran the charge card program at Continental, to establish the program for American. Weit I, 467 F.Supp. at 204. American joined Midwest in the spring of 1969, charging the (by now) standard cardholder interest rate of 18% per annum. Id. Midwest joined the Interbank Card Association, Inc. (Mastercharge) that year as well. Id. at 205. In 1970, First left the Midwest system, joined Bank Americard, and began soliciting the defendants’ correspondent banks for the first time. Id.
When plaintiffs first filed suit in 1970, defendants were still charging an interest rate of 18%, the same rate being charged today.
Defendants, in their motion for summary judgment, introduced affidavits by and depositions of their officers denying the existence of an agreement and giving business reasons for arriving at the 18% per annum charge card holder interest rate. David M. Kennedy, chairman of the Board of Directors, for Continental, stated that during the summer of 1966, he determined that Continental’s charge card should carry the highest interest rate legally permissible so as to make the system, for which Continental projected early high losses, profitable as soon as possible. Weit I, 467 F.Supp. at 201. Harris Bank’s senior vice-president, Carroll E. Prater, also testified that Harris decided to charge the maximum legal rate because “it was an expensive business to get into ... losses were very high.” Id.
Pullman officers stated that they arrived at an interest rate of 1%% per month based on their prior experience in the charge card business. Weit II, 478 F.Supp. at 289. Even at that rate, they did not expect the charge card program to be profitable for several years. Id. Frank Bauder, chairman of Central, testified that by the time Central decided to join Midwest in September of 1966, the l!/2% per month interest rate was taken for granted as necessary to cover costs. Id. at 288. James Kennedy, American’s second vice-president in charge of the bank’s charge card operations, gave similar reasons for American’s decision to charge llh% per month. Weit I, 467 F.Supp. at 204.
Defendants also argued that it was public knowledge that Bank Americard and other *475retail and oil credit cards were charging an interest rate of llk% per month or 18% per annum. Finally, they relied on written memorandum from their lawyers forbidding the discussion of interest rates as evidence that they did not agree on the uniform interest rate.
B.
Under Rule 56(e) defendants’ denials were sufficient to shift the burden to plaintiffs to produce some significant probative evidence tending to support their complaint. First National Bank of Arizona v. Cities Service, 391 U.S. 253, 289-90, 88 S.Ct. 1575, 1592-1593, 20 L.Ed.2d 569 (1968). The critical question then becomes whether plaintiffs presented enough evidence so that a rational trier of facts could find that this uniform interest rate resulted from an agreement among and between defendants rather than from independent identical decisions by individual bankers. See Ambook Enterprises v. Time, Inc., 612 F.2d 604, 613 (2d Cir. 1979), cert. dismissed, - U.S -, 101 S.Ct. 35, 65 L.Ed.2d 1179 (1980). In order to infer such an agreement, there must be more than merely parallel business conduct. See Theatre Enterprises, Inc. v. Paramount Film Distributing Corp., 346 U.S. 537, 541, 74 S.Ct. 257, 259, 98 L.Ed. 273 (1954). I think that plaintiffs did present evidence of more than merely parallel conduct, from which a jury could rationally conclude that defendants Continental, Harris, Pullman and Central agreed on uniform interest rates.
First of all, plaintiffs produced evidence showing that defendants Continental, Harris and Pullman knew the interest rates being contemplated by each. At the very first formal meeting of the group, which representatives of Continental and Harris attended, Harris officers stated they were afraid they may be bound by the Illinois usury limits, but that other states had enabling legislation allowing an interest rate of F/2% per month. From this statement it can be inferred that Harris hoped to charge Ph% per month. Then, in late June, 1966, officers of defendants Continental and Harris, along with representatives of First and Northern, met with the president of Bank Americard and discussed what Continental officers termed the “regular Ph% per month interest charge.” (Emphasis added.) From this statement it can be inferred that Continental was planning on charging 1%% per month interest.37 Because Continental knew in July, 1966, that Pullman was going to charge its cardholders an interest rate of 1V2% per month or 18% per annum, it can be inferred that Pullman told Continental as much.
This exchange of information regarding the “regular” interest rate and the interest rate being charged by Pullman is analogous to “[a] knowing wink [which] can mean more than words” in determining whether defendants agreed to fix prices. Esco Corp. v. United States, 340 F.2d 1000, 1007 (9th Cir. 1965). In Esco, the court held that an exchange of price information at a meeting called by Esco Corporation’s largest competitor was sufficient evidence, when combined with price uniformity, for inferring a price fixing conspiracy:
[S]uppose five competitors meet on several occasions, discuss their problems, and one finally states — “I won’t fix prices with any of you, but here is what I am going to do — put the price of my gidget at X dollars; now you all do what you want.” He then leaves the meeting. Competitor number two says — “I don’t care whether number one does what he says he’s going to do or not, nor do I care what the rest of you do, but I am going to price my gidget at X dollars.” Number three makes a similar statement— “My price is X dollars.” Number four says not a word. All leave and fix “their” prices at “X” dollars.
*476We do not say the foregoing illustration compels an inference in this case that the competitors’ conduct constituted a price-fixing conspiracy, including an agreement to so conspire, but neither can we say, as a matter of law, that an inference of no agreement is compelled.. .. [I]t remains a question for the trier of fact....
Id.
Here, defendants Continental and Harris said they wouldn’t fix prices,38 yet in discussions between the two banks, representatives of Harris spoke of iy2% enabling legislation and Continental officers referred to “regular 1V2%” interest rates. In the same way, Pullman told Continental what it was going to charge. The Supreme Court has held that an exchange of price information, in an industry dominated by relatively few sellers, is itself a violation of section 1 of the Sherman Act because “[pjrice is too critical, too sensitive a control to allow it to be used even in an informal manner to restrain competition.” United States v. Container Corp. of America, 393 U.S. 333, 338, 89 S.Ct. 510, 513, 21 L.Ed.2d 526 (1969). If the Supreme Court could find that the exchange of price information was sufficient for inferring a price-fixing agreement, surely we should consider it as some evidence, when combined with subsequent parallel pricing, joint action, product uniformity and motive from which an agreement could be inferred.39
Plaintiffs introduced no evidence indicating that defendant Central exchanged any interest rate information with defendants Continental, Harris and Pullman. Yet when Central joined Midwest in the fall of 1966, it charged the same interest rate as discussed by the other defendants, even though it could have charged the higher rate allowed to National banks. It is not necessary for each defendant to have participated in every act of the conspiracy in order to be charged with such, as long as they had a common purpose connecting their acts. See Esco Corp. v. United States, supra, 340 F.2d at 1006. Here, Central participated in other activities from which its participation in the conspiracy can be inferred.
The district court judge did not consider the joint lobbying activities by defendants Continental, Harris, Central and Pullman,40 stating that the prejudice of this evidence outweighed its probative value. Weit I, 467 F.Supp. at 207-08 n. 22. The majority adopts this holding, but I respectfully disagree. Federal Rule of Evidence 403 is meant to exclude evidence which tends to horrify, evoke sympathy or increase a desire to punish due to prior bad acts, and whose probative value is slight. 10 Moore’s Federal Practice § 403.10[1], at IV-75 (2d Ed. 1979). Defendants’ lobbying activities do not fall into any of these categories.
While defendants’ united support of the 18% per annum interest rate is not in itself illegal under Eastern Railroads Presidents Conference v. Noerr Motor Freight, Inc., 365 U.S. 127, 81 S.Ct. 523, 5 L.Ed.2d 464 (1961),41 it is certainly probative of an existing agreement to fix interest rates at that level. The inference is very readily drawn that defendants could not have worked together on the same bill, at a time when a *477number of different interest rates could have been agreed to, and when defendants had differing understandings regarding the legal restrictions on their interest rates, without implicitly agreeing that 18% was the rate they thought best and would therefore charge. Indeed, this is the rate they were each charging when they agreed to support a credit card interest bill. The Supreme Court has held that such a concerted effort, when defendants conformed to the arrangement, is probative of a price fixing conspiracy. See United States v. Paramount Pictures, 334 U.S. 131, 142, 68 S.Ct. 915, 921, 92 L.Ed. 1260 (1948). Thus, defendants’ joint lobbying activities should be considered as further evidence of an implicit agreement to charge 18% interest rate per year.
Another factor contributing to the evidence from which an agreement to fix interest rates may rationally be inferred is defendants’ express agreement to standardize everything about their charge cards other than marketing strategy and interest rates. Defendants admitted that “[h]omogeneity was legislated into the product by edict. In fact, this identity is the philosophic heart and soul of the compatible agreement each bank must sign to gain admission into the system.”42 Plaintiffs’ expert witness testified that these uniform requirements were no more essential to the compatibility of the charge card system and the interchange of sales slips than they are to the interchange of checks.43
In a competitive industry, such standardization could perhaps enhance price competition. L. Sullivan, Antitrust § 98 at 276 (1977). But in an oligopoly, and plaintiffs have shown that the Chicago banking industry may be fairly characterized as such, non-price competition is valuable, and anything tending to standardize non-price terms harms competition. Id., § 99 at 279. The Ninth Circuit recognized this harm in C-O-Two Fire Equipment Co. v. United States, 197 F.2d 489 (9th Cir. 1952), when it stated that product standardization of a product that is not naturally standardized facilitates the maintenance of price uniformity. Id. at 493. Thus, product standardization was another factor, in addition to parallel conduct, from which a conspiracy to fix prices could be inferred. Id.
Here, under competitive conditions, credit card characteristics would have changed as independent banks experimented with one or another promotional features and cardholders and merchants gave their business to the banks offering the most attractive combination.44 Instead, defendants Continental, Harris, Central and Pullman each signed an agreement, on the samé day, which artificially homogenized their product and eliminated an area of potential competition. Their defense that such standardization was needed to eliminate chaos among the merchants and public, see Weit I, 467 F.Supp. at 211, should not be definitive of the issue, as industry self-regulation should be viewed with suspicion. See United States v. Socony-Vacuum Oil Co., 310 U.S. 150, 220-22, 60 S.Ct. 811, 842-843, 84 L.Ed. 1129 (1940).
Plaintiffs also introduced evidence of defendants’ opportunity to conspire. Aside from the formal study group meetings, which representatives of Continental, Harris and American attended, and of which Central and Pullman were kept informed, defendants’ officers met informally on numerous occasions. Opportunity to conspire, standing alone, is insufficient for inferring a conspiracy. It may be considered, however, in determining whether all of the evidence, in addition to parallel behavior, warrants an inference of common, rather than individual conduct. L. Sullivan, Antitrust, § 110 at 317 (1977). Evidence of meetings between defendants, presenting an opportunity to conspire, were plus factors in finding a price-fixing agreement in C-O-Two Fire Equipment Co. v. United States, even though there was no evidence of what was discussed. C-O-Two Fire Equipment Co., *478supra, 197 F.2d at 493.45 And in Esco Corp. v. United States, 340 F.2d 1000 (9th Cir. 1965), the court affirmed a jury finding of price-fixing based on evidence that defendants were at two meetings during which the elements necessary to price fixing were discussed, although there was no evidence of an agreement other than parallel behavior. The court stated:
As in so many other instances, it remains a question for the trier of fact to consider and determine what inference appeals to it (the jury) as most logical and persuasive, after it has heard all the evidence as to what these competitors had done before such meeting, and what actions they took thereafter, or what actions they did not take.
Id. at 1007.
Defendants denied any discussion of interest rates at these formal and informal meetings. But the fact of their meetings, combined with their knowledge of the interest rates to be charged by fellow defendants, their decision to lobby together in the legislature for an 18% rate and their express agreement on non-interest aspects of their parallel conduct, provide sufficient evidence from which a jury could infer that interest rates were in fact discussed. The jury should have the opportunity to decide for itself that defendants’ denials are more credible than plaintiffs’ circumstantial evidence of an agreement.
Finally, plaintiffs introduced evidence of defendants’ motive to conspire. It was plaintiffs’ inability to show a motive to agree and benefits obtained through the agreement which led the Supreme Court to affirm a summary judgment for defendants in First National Bank of Arizona v. Cities Service Co., 391 U.S. 253, 287, 88 S.Ct. 1575, 1591, 20 L.Ed.2d 569 (1968). In the present case, defendants admitted the motive for doing exactly what they are accused of: defendant officers testified that they were afraid of aggressive competition in the new market for credit cards, which they thought would result in chaos. If someone entered the market at a lower rate, which Harris thought it may have been forced to do, given the state usury laws, the other defendants may have marketed their cards at a lower rate as well. None of the banks wanted to face this possibility as they were afraid of large losses in starting the new program.46
Defendants introduced independent business reasons to explain their decisions to charge an 18% per annum interest rate. It is up to the jury, however, and not the trial judge, to decide which explanation for defendants’ action is more reasonable. See Continental Baking Co. v. United States, 281 F.2d 137, 143-46 (6th Cir. I960).47 Fur*479thermore, the legitimate business reasons which defendants suggest motivated their actions do not defeat the possibility that defendants acted collusively. Reading Industries, Inc. v. Kennecott Copper Co., 1979-2 Trade Cases H 62,906 at 79,215 (S.D. N.Y.1979). The Supreme Court has stated: “[t]his evidence [of business judgment], together with other testimony of any explanatory nature, raised fact issues requiring the trial judge to submit the issue of conspiracy to the jury.” Theatre Enterprises, Inc. v. Paramount Film Distributing Corp., 346 U.S. 537, 542, 74 S.Ct. 257, 260, 98 L.Ed. 273 (1954). In Theatre Enterprises, as in Weit I, defendants had denied any agreement and had introduced evidence of local conditions, attributing their uniform action to individual business judgment. The Supreme Court went on to affirm the jury verdict for defendants, over plaintiff’s argument that the district court should have directed a verdict, but it was the jury, and not the court making the ultimate decision. When defendants’ credibility is at issue, as it was in Theatre Enterprises and is in Weit I, directed verdicts and summary judgments “should be used sparingly,” because “[i]t is only when the witnesses are present and subject to cross examination that their credibility and the weight to be given their testimony can be appraised.” Poller v. Columbia Broadcasting System, Inc., 368 U.S. 464, 473, 82 S.Ct. 486, 491, 7 L.Ed.2d 458 (1962).48 In the present case, the district judge overstepped his proper role by determining for himself that defendants’ explanations were more credible than plaintiffs’ explanation of the evidence. His entry of summary judgment for defendants was therefore improper.
Defendants emphasize that they were warned at an early stage of potential antitrust violations and that their lawyers monitored the study group meetings to ensure compliance. This information should not be dispositive of defendants’ evidence. First of all, there is no evidence that the warning was given before defendants started discussing charge card programs on a regular basis. To the contrary, the evidence shows that the warning wasn’t given until July 25, 1966, almost two months after defendants began meeting formally, and one month after 18% — or llh% per month — had become “the regular interest rate.” Secondly, lawyers were not present every time defendants met: no lawyer was with the officers of Harris and Continental on their cross-country trip to meet with the president of Bank Americard to discuss “the regular” interest rate, nor was a lawyer present when officers of Continental had dinner with the president of Pullman.
Most importantly, these defendants and future sophisticated defendants should not be allowed to escape allegations of illegal conspiracies as easily as by leaving a paper trail drafted by their lawyers. No conspirator today is going to publicly agree to joint action, nor are they going to leave a written record of their agreement. Instead, conspirators are likely to go to great pains to conceal their agreement, and a lawyer’s memorandum would accomplish just this.49 *480That defendants were warned by their lawyers and were aware of possible anti-trust violations should not be completely disregarded. Rather, defendants’ statements that they carefully obeyed their lawyers’ warnings should be evaluated by the trier of fact along with plaintiffs’ evidence of an agreement.
In sum, plaintiffs have rebutted Continental’s, Harris’, Pullman’s and Central’s denials with evidence of more than the merely conscious parallelism held insufficient to withstand a summary judgment in Cities Service, supra, 391 U.S. at 290, 88 S.Ct. at 1593. They produced evidence that Continental, Harris and Pullman communicated directly regarding the interest rates each was going to charge; Continental, Harris, Pullman and Central took joint action on legislation regarding legal interest rates and on most other aspects of the charge card system; and that all four banks had a motive to agree to fix interest rates. All of these factors have been held sufficient, when combined with a showing of parallel behavior to withstand motions for summary judgment. See De Jong Packing Co. v. United States, 618 F.2d 1329, 1334 (9th Cir.), cert. denied,-U.S.-, 101 S.Ct. 783, 66 L.Ed.2d 603 (1980); L. Sullivan, Antitrust § 110 at 316 (1977). Plaintiffs, having presented evidence from which an agreement to fix prices may rationally be inferred, should be given a chance to present their case against these four defendants to a jury.
On the other hand, plaintiffs presented significantly less evidence regarding defendant American’s participation in the horizontal conspiracy. American did send a representative to the formal group meetings, but there is little other evidence that it met with the other defendants on a formal or informal basis. It did not participate in drawing up the formal agreement, nor did it sign the agreement with the other defendants. It did not participate in the lobbying activities with other defendants. Most important, it did not have the motive to conspire to set an 18% interest rate as did the other defendants. By the time American issued its charge card, the 18% credit card interest rate legislation had been in effect for two years. Every other bank seemed firmly set in its pattern of charging an 18% interest rate. Thus, American did not have to worry about being undercut by its competitors, and was free to set the rate it felt would be best for recouping start-up costs and initial losses. Plaintiffs did not introduce sufficient evidence of American’s role in the conspiracy and motive to conspire to overcome American’s denial of price fixing.
III. THE VERTICAL CONSPIRACY
I agree with the majority’s decision affirming the summary judgments granted defendants Continental, Harris and Central regarding the alleged vertical conspiracies with their respective correspondents. I also agree that if there were no horizontal conspiracy, plaintiffs would lack standing to assert a vertical conspiracy claim against defendant Pullman.
. The district court’s opinion granting summary judgment for defendants Continental, Harris . and American as to the charges of horizontal conspiracy and for Continental as to the charge of vertical conspiracy is reported in Weit v. Continental Ill. Nat'l Bank & Trust Co., 467 F.Supp. 197 (N.D.Ill.1978) (hereinafter “Weit /’’). The decision granting summary judgment for defendants Central and Pullman on both the horizontal and vertical conspiracy claims and for defendant Harris on the vertical conspiracy claim is reported at Weit v. Continental Ill. Nat’l Bank & Trust, 478 F.Supp. 285 (N.D.Ill. 1979) (hereinafter “Weit II”).
. On appeal from a grant of summary judgment, the appellate court is to review the record and determine for itself whether there are any genuine issues of material fact. 6 Pt. 2 Moore’s Federal Practice *' 56.27[1], at 56-1555 (2d Ed. 1980).
. First was named as a non-defendant co-conspirator in Counts I and III of plaintiffs’ third amended complaint. Although First was a founding member of Midwest, it left Midwest and joined the Bank Americard System in 1970. Weit I, 467 F.Supp. at 200 n. 3.
. Shull Aff. at 2.
Defendants Harris and Pullman are state chartered banks, and defendants Continental and Central are nationally chartered banks, as is First National Bank.
. lll.Ann.Stat. ch. 1672, § 106 (Smith-Hurd Supp.1980).
. Shull Aff. at 3.
. Deposition of Kenneth V. Zweiner at 17.
. Deposition of David M. Kennedy at 64-65.
. Deposition of James R. Kennedy at 357.
. Deposition of Arthur Stump at 40, 76-77.
. A memorandum by Thomas G. Patterson to John B. Tingleff, both Continental officers, stated “[Valley National Bank, Phoenix] believes that if anyone goes in Chicago others will and this may result in chaos in the market. Could be [disastrous].” Weit /, 467 F.Supp. at 200.
. Plaintiffs’ Ex. 6: Feasibility Study — Continental Illinois Nat’l Bank & Trust, Co., dated July 1966, at 45-46.
. Deposition of Sheldon Swope, Vice-President of Continental, at 45.
. Deposition of Allen Stults, president of American, at 24-25.
. Northern participated in the original planning sessions, but dropped out of the program in August, 1966. Weit I, supra at 200, n. 4.
. Deposition of Frank Bauder at 37; Defendants’ Ex. D9 and Dll.
. Plaintiffs’ Ex. 93 and 140.
. Memorandum of Robert K. Miller to John Tingleff, dated July 14, 1966, Ex. A to Defendant Continental’s Answers to Plaintiffs’ Interrogatories, filed November 11, 1977 at pp. 23-24.
. Prater Deposition, Ex. 50; Kranzley Deposition, Ex. 8E.
. Deposition of John Mattmiller (Northern), at 39-42.
. Plaintiffs’ Ex. 6 at 43.
. Lindgren Deposition, Ex. 2.
. Defendants’ Ex. A6; Prater Deposition, Ex. 55 and 56.
. Defendants’ Ex. A6.
. Prater Deposition, Ex. 55.
. Prater Deposition, Ex. 56.
. Prater Deposition, Ex. 55.
. American did not join Midwest until 1969, although a representative of American attended the group meetings. Weit I, 467 F.Supp. at 202.
. Ill.Ann.Stat. ch. 74, § 31 (Smith-Hurd, 1966).
. Ill.Ann.Stat. ch. 74, § 4 (Smith-Hurd, 1966).
. Appellants’ brief at 65, citing Plaintiffs’ Ex. 105 and 733.
. Deposition of William Dillon at 13.
. Dillon Deposition, Ex. 19 and 15A.
. Dillon Deposition, Ex. 16A.
. Dillon Deposition at 210-11; Ex. 6 and 9.
. Ill.Ann.Stat. ch. 74, § 4.2 (Smith-Hurd Supp. 1980).
. It can also be inferred from this statement that Continental was saying “this is the only rate a bank should charge.” It is interesting to note that Continental referred to 18% as the “regular” interest rate several months before it consulted with Robert Bloom, Chief Counsel to the Comptroller of the Currency, The United States Treasury, regarding its interpretation of the Illinois Consumer Finance Act, Weit I, 467 F.Supp. at 201.
. Continental circulated the Seeley memorandum forbidding the discussion of interest rates to other Midwest banks, including Harris. See nn. 19 and 20, and accompanying text, supra.
. Defendants argue that it was common knowledge that l‘A% per month was the “regular” interest rate. This does not prevent them from agreeing to charge that rate, however.
. These four defendants were Midwest members when Midwest hired William Dillon.
. Plaintiffs did not allege that this activity in and of itself constituted an illegal conspiracy. Rather, they introduced it as evidence of the alleged agreement between defendant banks to fix the interest rate of 18%. This evidence thus falls within an exception to the Noerr rule being the “established rule of evidence that testimony of prior or subsequent transactions, which for some reason are barred from forming the basis for a suit, may nevertheless be introduced if it tends reasonably to show the purpose and character of the particular transactions under scrutiny.” United Mine Workers of America v. Pennington, 381 U.S. 657, 670 n. 3, 85 S.Ct. 1585, 1593, n.3, 14 L.Ed.2d 626 (1965).
. Egan Deposition, Ex. 16 at 99.
. Shull Aff. at 5.
. Shull Aff. at 6.
. The district court distinguished C-O-Two from the present case by saying that a finding of conspiracy was warranted in light of other factors: identical bids, unnecessary product standardization, illegal licensing contracts, dealer policing, and identical price increases at times of surplus, coupled with the fact that the defendants offered no rebuttal evidence. Weit I, 467 F.Supp. at 214. Admittedly, plaintiffs in this case have not made as strong a showing of conspiracy as did the government in C-O-Two. But this case is not a challenge to the legal sufficiency of the evidence for a criminal conviction. All that is necessary to withstand a motion for summary judgment, which is the only issue at this point, is a showing of at least one other factor, in addition to parallel pricing, from which a jury could infer an agreement. L. Sullivan, Antitrust § 110, at 317 (1977). Plaintiffs have shown at least three such factors, and their opportunity evidence merely contributes to the overall picture.
. At the same time, defendant Continental, which thought it was bound by the Illinois Consumer Finance Act, gave up the opportunity to charge a higher interest rate — 36% per annum on balances up to $150 — which would have enabled it to recoup its projected losses much more quickly. Such an apparent contradiction in self interest “strengthens considerably the inference of conspiracy.” Milgram v. Loews, Inc., 192 F.2d 579, 583 (3rd Cir. 1951).
. In Continental, the government charged Continental with participating in a price fixing conspiracy and introduced evidence showing that defendants met prior to each price increase. As in Weit I, the government did not introduce any evidence of a specific agreement. The trial judge decided for himself that there was an agreement, and consequently refused defendants the opportunity to present evidence of economic factors leading to these price increases. The Sixth Circuit reversed, stating that it was up to the jury to determine whether *479an agreement existed, based on all the evidence. Id. at 143. Weit I is analogous, in that here, the trial judge decided for himself that defendants’ explanations were more reasonable than plaintiffs and that there was no agreement.
. It is true that defendants’ credibility in the present case is not at issue in the same way in which it was at issue in Poller. There, the issue was defendants’ intent, as their actions in cancelling plaintiffs’ affiliation contract and then buying its equipment would have been legal unless done with an intent to monopolize. CBS, in its motion for summary judgment, presented “substantial evidence tending to show the nonexistence of conspiratorial behavior.” Cities Service, supra, 391 U.S. 253, 285, 88 S.Ct. 1575, 1590, 20 L.Ed.2d 569 (discussing the difference between Poller and Cities Service). Nonetheless, the Court held that the denials of unlawful intent by “interested parties,” Poller, supra, 368 U.S. at 468, 82 S.Ct. at 488, were insufficient to rebut plaintiffs allegations of conspiracy for purposes of granting a summary judgment. Id. at 473, 82 S.Ct. at 491.
. I am not implying that defendants’ lawyers participted in a cover-up. Defendants could easily have discussed forbidden subjects in their informal meetings, however, while scrupulously obeying their lawyers during formal sessions.