DONALD RUSSELL, Circuit Judge:
On November 25, 1980, the appellants, Portsmouth Paving Corporation and its president R. Curtis Saunders, Jr., were indicted, together with three other corporations and eight other individuals, for conspiracy to allocate contracts and to rig bids in violation of section 1 of the Sherman Act, 15 U.S.C. § 1. After several plea agreements, the Government brought to trial two corporate and five individual defendants, including the appellants. Following an eight-day trial beginning on February 23, 1981, the jury was unable to agree on a verdict and the district court declared a mistrial. Subsequent to a ten-day second trial that began on April 20, 1981, the jury returned guilty verdicts against Portsmouth Paving, Saunders, and three other defendants, not parties to this appeal; two individual defendants were acquitted. Portsmouth Paving and Saunders were fined [316]*316$400,000 and $30,000, respectively, and Saunders was also sentenced to imprisonment for a period of time not exceeding 120 days with probation for three years following release. They then filed this appeal.
The appellants were charged with combining and conspiring “[t]o allocate ... roadway construction and surface paving contracts” and “[t]o refrain from bidding or to submit collusive, non-competitive and rigged bids ... in connection with the roadway construction and surface paving contracts let in the Tidewater area” of Virginia by federal, state, and local authorities. The Tidewater area was defined in the indictment to include the cities of Chesapeake, Norfolk, Portsmouth and Virginia Beach.1 The indictment also alleged that the defendants conspired “[b]eginning sometime in or about 1963, and continuing thereafter, the exact dates being unknown to the grand jury.” The purported agreement covered two types of projects: Annually scheduled resurfacing work in each of the four Tidewater cities and other nonscheduled projects throughout the Tidewater region. According to the Government’s theory, the conspirators would trade projects among themselves by agreeing to withhold bids or to submit artificially high “complementary” bids on certain projects.2 Citing several sources of error, however, the appellants contend that their convictions should be reversed.
I
Portsmouth Paving and Saunders argue at considerable length that the evidence presented against them at both trials was insufficient as a matter of law to sustain the jury’s verdict.3 In determining whether the evidence was sufficient to prove the offense charged,4 we must con[317]*317sider whether any rational trier of fact could find guilt beyond a reasonable doubt when the evidence is viewed in the light most favorable to the Government. Jackson v. Virginia, 443 U.S. 307, 319, 99 S.Ct. 2781, 2789, 61 L.Ed.2d 560 (1979); United States v. Shaver, 651 F.2d 236, 238 (4th Cir.1981). Application of that standard in this case compels the conclusion that the evidence was more than sufficient.
As a necessary predicate to defining the essential elements of the crime, we note that the contract allocation and bid rigging scheme alleged in the indictment is illegal per se under section 1 of the Sherman Act. See United States v. Koppers Co., Inc., 652 F.2d 290, 293 (2d Cir.), cert. denied, 454 U.S. 1083, 102 S.Ct. 639, 70 L.Ed.2d 617 (1981) (bid rigging, territorial allocation in Connecticut highway maintenance); United States v. Azzarelli Construction Co., 612 F.2d 292, 294 (7th Cir. 1979), cert. denied, 447 U.S. 920, 100 S.Ct. 3010, 65 L.Ed.2d 1112 (1980) (bid rigging on Illinois highway projects); United States v. Flom, 558 F.2d 1179, 1183 (5th Cir.1977) (bid rigging on sales of reinforcing steel bars). Section 1 proscribes “[ejvery contract, combination in the form of trust or otherwise, or conspiracy, in restraint of trade or com merce.” Early in the history of the statute, the Supreme Court read section 1 to prohibit only those agreements resulting in unreasonable restraints of trade. See Chicago Board of Trade v. United States, 246 U.S. 231, 238, 38 S.Ct. 242, 244, 62 L.Ed. 683 (1918). Notwithstanding the unreasonableness requirement, certain business agreements, because of their inherent tendency to eliminate competition, are presumed unreasonable and are therefore illegal per se. See Northern Pacific Railway Co. v. United States, 356 U.S. 1, 5, 78 S.Ct. 514, 518, 2 L.Ed.2d 545 (1958); Krehl v. Baskin-Robbins Ice Cream Co., 664 F.2d 1348, 1356 (9th Cir.1982). Under such circumstances, the Government is not required to prove unreasonableness.
Price fixing agreements are typical of those agreements per se violative of the Sherman Act. See United States v. McKesson & Robbins, Inc., 351 U.S. 305, 309-10, 76 S.Ct. 937, 940, 100 L.Ed. 1209 (1956); United States v. Socony-Vacuum Oil Co., 310 U.S. 150, 218, 60 S.Ct. 811, 842, 84 L.Ed. 1129 (1940); National Electrical Contractors Association v. National Constructors Association, 678 F.2d 492 (4th Cir.1982); United States v. Society of Independent Gasoline Marketers, 624 F.2d 461, 465 (4th Cir.1979), cert. denied, 449 U.S. 1078, 101 S.Ct. 859, 66 L.Ed.2d 801 (1981). Even more egregiously contrary to vital competition among businesses, however, is the contract allocation agreement charged in the instant case. Such an accord eliminates not only price competition, but also competition in service and product quality. 1 R. Callmann, The Law of Unfair Competition, Trademarks and Monopolies § 4.35, at 221 (4th ed.1981). Moreover, the collusive bid rigging dimension of the conspiracy charged makes the arrangement little less than a cartel,5 which is “never legally nor economically justifiable.” Id. § 4.20, at 109. The undisputed effect is to force the contracting government entities to pay more for the goods and services sought than they would “ ‘had there been free competition in the open market.’ ” United States ex rel. Marcus v. Hess, 317 U.S. 537, 539 n. 1, 63 S.Ct. 379, 382 n. 1, 87 L.Ed. 443 (1943) (circuit court’s description of “collusive bidding scheme” to defraud the United States); see United [318]*318States v. Bensinger Co., 430 F.2d 584, 589 (8th Cir.1970) (bid rigging agreement is “price-fixing agreement of the simplest kind”). As a result, we do not hesitate to conclude that the Government was not required to establish the unreasonableness of the conspiracy charged.
The Government was required to prove, nonetheless, that Saunders and Portsmouth Paving agreed with at least one other individual or entity to participate in the unlawful contract allocation and bid rigging charged.6 See South-East Coal Co. v. Consolidation Coal Co., 434 F.2d 767, 774 (6th Cir.1970), cert. denied, 402 U.S. 983, 91 5. Ct. 1662, 29 L.Ed.2d 149 (1971). The substance of the appellants’ argument is that the Government’s evidence failed to establish the time frame, territorial scope, and subject matter of the conspiracy alleged in the indictment. They further contend that their participation in the conspiracy charged was not proven.7 In essence, admitting that the evidence showed the existence of a number of separate and distinct conspiracies, the appellants maintain that what the Government did prove fatally varied from the terms of the indictment. Our review of the record, however, obliges us to disagree.
At the first trial, Government witness Robert Remington testified that as manager of Sam Finley, Incorporated he was a party to a contract allocation agreement covering the cities of Norfolk, Chesapeake, Portsmouth, and Virginia Beach beginning “about late in the fall of 1963 or early in the spring of 1964.” According to Remington, representatives of five companies, including Saunders of Portsmouth Paving, attended the first meeting. He testified that “[a]t the meeting we agreed to not fight, to get along, try to provide work. Everybody get their share of the work.”8 The companies ordinarily met at least annually through 1979, the frequency “depending on the volume of work that was up coming that needed to be discussed.” At the second trial, Remington described the time frame of the agreement between the contractors in similar terms, affirming that Saunders attended the meetings “[f]rom the very beginning to the very end,” that Saunders “was a regular attendee.”
• While several others besides Remington testified at both trials to the continuing nature of the contractors’ agreement, the evidence reveals that during perhaps two intervals, totaling approximately two and one-half years, the contractors were unable to agree on the specific application of the bid rigging arrangement to the available work. Nevertheless, this evidence establishes nothing more than a temporary lull in the parties’ ongoing efforts to keep competition between them to a minimum. Absent an affirmative showing of the termination of the agreement, the conspiracy must be presumed to have continued. See [319]*319Joyner v. United States, 547 F.2d 1199, 1203 (4th Cir.1977); United States v. Basey, 613 F.2d 198, 202 (9th Cir.1979), cert. denied, 446 U.S. 919, 100 S.Ct. 1854, 64 L.Ed.2d 274 (1980); United States v. Menendez, 612 F.2d 51, 54 (2d Cir.1979). The conspiracy initiated in 1963 or 1964 did not clearly terminate until the fall of 1979 when, according to Fred A. Haycox, president of Asphalt Roads & Materials Co., Inc., the contractors ceased meeting “[b]ecause of the investigation and some indictments.”
In addition to contending that the Government’s evidence failed to prove the time frame of the conspiracy charged, the appellants assert with respect to the proof of territorial scope that economic feasibility would not allow Portsmouth Paving to bid on contracts originating in Virginia Beach. Whatever responsible business practices might have demanded, however, the records of both trials affirmatively disclose that Portsmouth Paving and Saunders agreed to the allocation of contracts and the rigging of bids with companies based in Norfolk and Virginia Beach. Remington defined the agreement as covering all four cities of the Tidewater region. Likewise, Rufus Dalton, vice president of one of the Norfolk paving firms, testified that three contractors from Virginia Beach and three contractors from outside Virginia Beach, including Portsmouth Paving, had made an arrangement for the division of certain work according to territory. Elvin Ray Waterfield, associated with the Virginia Beach firm of Ashland-Warren, Inc., also described the allocation agreement as encompassing the four Tidewater cities. Haycox similarly defined the'scope of the agreement.
The evidence adduced at both trials regarding the subject matter of the conspiracy was equally substantial. Our examination of the record confirms that the two above-mentioned types *of paving contracts, the annual “schedule” resurfacing contracts for each city and the “nonschedule” public paving project contracts, were allocated between the conspirators. The schedule work typically was divided on an annual basis between two groups of contractors. The parties agreed that the three Virginia Beach companies were to allocate among themselves the Virginia Beach schedule work and that Portsmouth Paving and the two Norfolk-based firms were to allocate among themselves the schedule work derived from Norfolk, Chesapeake, and Portsmouth. While not all the companies expressed an interest in each nonschedule project, testimony at both trials was sufficient to support the conclusion that all the companies agreed that an effort to allocate the nonschedule projects between the interested contractors would be made whenever a nonschedule project was let for bids.
Government witnesses testified unequivocally that the rigged projects yielded higher prices. Additionally, discussions at meetings attended by representatives of all six companies focused on both schedule and nonschedule work. The evidence clearly allowed the jury to draw any inferences necessary to arrive at the conclusion that the arrangements concerning schedule and non-schedule work were integral parts of a “single enterprise,” rather than “separate adventures of like character,” Kotteakos v. United States, 328 U.S. 750, 769, 66 S.Ct. 1239, 1250, 90 L.Ed. 1557 (1946), designed to effect the singular result of decreased competition in the paving industry of Virginia’s Tidewater cities.
Finally, while we are mindful that guilt by mere association enjoys no sanction in our system of criminal law, we must reject the appellants’ argument that the evidence was insufficient to prove their participation in the conspiracy. As the representative of Portsmouth Paving, Saunders regularly attended, and often organized, the contractors’ secret meetings.9 Daltón and Remington testified at both trials to Saunders’ active involvement in the allocation [320]*320and bid rigging scheme. Saunders was present at the first meeting in 1963 or 1964 and participated through the end of the conspiracy in 1979. The evidence established his partnership in collusive commitments relating to schedule and nonschedule work. The appellants are simply too entangled in the record evidence to justify any conclusion other than that a rational trier of fact could have found guilt beyond a reasonable doubt.
II
A significant portion of the testimony adduced at the second trial10 referred to statements, discussions, understandings, and agreements of the various representatives of the conspiring companies. Under Rule 801(d)(2)(E) of the Federal Rules of Evidence, such statements attributable to the nonwitness company representatives are not excludable as hearsay if made “during the course and in furtherance of the conspiracy.” This hearsay “exception” applies, however, only if a fair preponderance of independent evidence establishes the existence of and the defendants’ participation in the conspiracy. See United States v. Dockins, 659 F.2d 15, 16 (4th Cir.1981) (substantial evidence); United States v. Gresko, 632 F.2d 1128, 1131 (4th Cir.1980) (sufficient evidence to take question to jury); United States v. McCormick, 565 F.2d 286, 289 (4th Cir.1977), cert. denied, 434 U.S. 1021, 98 S.Ct. 747, 54 L.Ed.2d 769 (1978); Joyner v. United States, 547 F.2d 1199, 1203 (4th Cir. 1977) (substantial evidence to demonstrate prima facie case); United States v. Jones, 542 F.2d 186, 203 (4th Cir.), cert. denied 426 U.S. 922, 96 S.Ct. 2629, 49 L.Ed.2d 375 (1976). Nonetheless, we conclude that the district court committed no error in admitting the statements of coconspirators against Saunders and Portsmouth Paving because our review of the record convinces us of the presence of such independent evidence.
Remington testified that he “talked to Curtis [Saunders] ... mainly to find out if it was all right with him if I got the job.” He later stated: “I went along with quite a few jobs prior to Great Neck Road, so that when my turn came, why, they were committed to me for Great Neck Road for my commitments or going along with them and putting in complementary bids on some jobs previous to that.” Waterfield responded in the affirmative when asked whether he had ever met with his Tidewater competitors. He answered in the same fashion when asked whether there had “ever come a time when you spoke in coded language over the telephone to any of your competitors to exchange complementary bid prices.” Waterfield also testified that Saunders was present at a meeting where Waterfield had concluded, based on a conversation between Dalton and Saunders, “that we wouldn’t bid any of the asphalt work outside of the City of Virginia Beach to resurface it.”
Haycox declared that through 1979 he attended meetings at which representatives from all six companies were present. In addition, he made specific reference to Saunders’ attendance at meetings where Virginia state and Navy jobs were discussed. In response to the court’s question whether “Saunders in addition to being there took part in the meetings,” Haycox replied, “I’d say everybody there took part in the meeting.” Dalton testified that he “talked to Curtis Saunders I guess almost every week of my life for a period of four or five years ... I’d say from 1975 until 1980.” When asked whether Saunders ever gave him “a price to bid in any city as a complementary bid,” Dalton replied, “Oh, yes.” He also affirmed that he gave Saunders “prices to bid on occasions, as well.” Although the independent proof requirement for the admissibility of otherwise inadmissible hearsay can be extraordinarily burdensome in somq conspiracy trials, the cited testimony fulfills that requirement in the instant case. Beyond that, since Saunders is a party, Rule 801(d)(2)(A) renders admissible against him all statements attributed to Saunders.
[321]*321The more complicated hearsay objection raised by the appellants stems from testimony of Remington and Waterfield concerning a telephone call purportedly made by Remington to Saunders’ office. Remington was asked on direct examination about a call he made to Saunders “to get an update on [a] request” for information pertaining to another contractor’s intentions on a 1975 Battlefield Boulevard job. Remington testified over counsel’s objection as follows:
Well, I called Mr. Saunders’ office, and the secretary said he wasn’t in. And I said, “You think you could get him on the car radio?” And she said, “Yes, I’ll try.” So a few minutes later she came back on the air and said, “Mr. Saunders said that the air is clear in Chesapeake.”
Waterfield later testified over objection to the same incident, stating that he was standing at the doorway of Remington’s office when Remington hung up the phone. According to Waterfield, “Bob Remington laid down the phone and he said ‘That was Curtis Saunders’ secretary and she said that the sky was clear in Chesapeake.’ ”
Remington’s testimony involves assertions by nonwitnesses on two levels — Saunders’ statement and the secretary’s statement. See Fed.R.Evid. 801(a). Under the rationale of Rule 805,11 before the secretary’s statement may be admitted, both levels must either be excluded from the definition of hearsay or satisfy some exception to the hearsay rule. The appellants necessarily concede that the statement attributed to Saunders is admissible. A party’s own statements offered against him are excluded from the definition of hearsay by Rule 801(d)(2)(A).
The admissibility of the statement attributed to the secretary depends on an analysis of the hearsay “exceptions” contained in clauses (C) and (D) of Rule 801(d)(2). Clause (C) provides that a statement offered against a party is not hearsay if it is “a statement by a person authorized by him to make a statement concerning the subject.” This provision states the “orthodox” rule, and demands as a prerequisite to admissibility a showing based on evidence independent of the alleged hearsay that the declarant is an agent of the party with authority to speak on the subject. See 4 J. Weinstein & M. Berger, Weinstein’s Evidence 1801(d)(2)(C)[01], at 801-151-53 (1979). Ordinarily, under this rule, an employee’s admissions damaging to his employer would be inadmissible on the grounds that the employee was not authorized to make damaging admissions. See id. 1801(d)(2)(D)[01], at 801-159. Likewise, in the case at bar, while there is independent evidence of the agency status of the one with whom Remington spoke, there is no evidence, beyond that implicit in the statement sought to be admitted, that she was authorized by Saunders to make the damaging admission about the “air ... in Chesapeake.”
Clause (D) broadens the narrower “orthodox” rule embodied in clause (C). Clause (D) excludes from the definition of hearsay when offered against a party a statement “by his agent or servant concerning a matter within the scope of his agency or employment, made during the existence of the relationship.” Here, too, independent evidence establishing the existence of the agency must be adduced, but specific authorization to speak need not be shown. That the statement is made within the scope of the agency is sufficient. The issue, then, is whether the record contains independent evidence demonstrating that the woman with whom Remington spoke was an agent of Saunders speaking about a matter within the scope of her employment.12 We conclude that the record does contain such evidence.
[322]*322First, Remington testified that he “called Mr. Saunders’ office.” Not only does this testimony authenticate the occurrence of the telephone call in accordance with the standard illustrated by Rule 901(b)(6),13 but the testimony also supports the inference that the one who answered the telephone was Saunders’ agent. One would usually and properly assume upon the dialing of a business office phone number that the person who answers is employed by and has the authority to speak for the business.
Second, Remington testified that “the secretary” answered the call. That a businessman’s secretary is an agent of the businessman for purposes of relaying messages to and from the businessman is common knowledge. Notwithstanding other testimony that casts some doubt on the accuracy of Remington’s characterization of the answerer as a secretary, his description of the one with whom he spoke constitutes a portion of the necessary independent evidence.
Finally, the two female employees in Saunders’ office in 1975, the year that Remington made his call, testified that they occasionally answered the telephone and by radio relayed messages to and from Saunders.14 This testimony, in conjunction with that previously identified, virtually compels the conclusion that the woman to whom Remington spoke was an agent of Saunders with the authority to relay messages from Saunders to those who called his business office. Under the terms of Rule 801(d)(2)(D), the statement attributed to the woman, which was a simple declaration of what Saunders had said, concerned “a matter” within the scope of her employment because part of her job entailed relaying messages from Saunders to business callers. That the woman’s statement was “made during the existence of the [agency] relationship” is an obvious corollary. Because the record contains the essential independent evidence of agency, the trial court did not err in admitting Remington’s account of the telephone conversation.
Waterfield’s testimony about the Remington telephone call presents hearsay implications on a third level. To paraphrase Waterfield, “Remington said that the secretary said that Saunders said ...”15 In this additional testimony of Waterfield, for purposes of further hearsay analysis, Remington is the declarant. See Fed.R.Evid. 801(b). While the appellants contest the Government’s argument that Remington’s statement is admissible under Rule 801(d)(2)(E) as that of a coconspirator of Saunders, a decision on that question is [323]*323not necessary.16 Waterfield’s testimony clearly falls within the hearsay exception delineated by Rule 803(1).
Regardless whether the declarant is available as a witness, Rule 803(1) provides that the hearsay rule does not exclude “[a] statement describing or explaining an event or condition made while the declarant was perceiving the event or condition, or immediately thereafter.” Three requirements must be satisfied before this exception may be applied. The requirements pertain to subject matter, perception, and time. See 4 J. Weinstein & M. Berger, supra, H 803(1)[01], at 803-72-77. The subject matter of Remington’s statement, the “event or condition” that he “describ[ed] or explained],” was the completed telephone conversation with Saunders’ office. A telephone call is certainly “an event,” and in this ease, in speaking to Waterfield, Remington clearly was describing and explaining the event of that telephone call.
Similarly, that the declarant “perceived]” the event is beyond dispute. Waterfield directly testified that he observed Remington hang up the telephone. We perceive events with our ears as much as with our eyes and, in the ordinary course of events, one hangs up a telephone at the end of a telephone conversation, after having “perceiv[ed]” the words of the other party.17
Finally, Remington’s statement falls squarely within the time strictures of Rule 803(1), having occurred “immediately” after the telephone call. Within a matter of no more than a few seconds, Remington “laid down the phone” and described the conversation to Waterfield. While Waterfield admittedly lacked the opportunity also to hear the conversation, the contemporaneity of the call and the explanation eliminated any possibility that Remington’s memory would render his explanation inaccurate and greatly reduced any likelihood of fabrication. This additional level of hearsay, therefore, fulfills the requirements of Rule 803(1). Consequently, as the Rules of Evidence render admissible each component of Waterfield’s testimony, the trial court did not err in overruling the appellants’ objection to its admission.
Ill
Saunders and Portsmouth Paving also complain of the district court’s refusal to allow testimony from an expert witness proffered to suggest an innocent explanation for the bidding patterns in the Tidewater region during the course of the conspiracy alleged. Their expert, a “consulting economist,” purportedly could have raised a reasonable doubt about the appellants’ part in the conspiracy by demonstrating that the bidding of Portsmouth Paving reflected the realities of market areas and the company’s capacity to compete.
Rule 702 of the Federal Rules of Evidence does provide for the admission of expert testimony when the expert’s “knowledge will assist the trier of fact ... to determine a fact in issue.” Rule 702, however, does not require the admission of all proffered expert testimony; the district judge has broad discretion to decide whether such testimony ought to be admitted as helpful to the jury. See Salem v. United States Lines Co., 370 U.S. 31, 35, 82 S.Ct. 1119, 1122, 8 L.Ed.2d 313 (1962); United States v. Vik, 655 F.2d 878, 880 (8th Cir. 1981); United States v. Lopez, 543 F.2d 1156, 1158 (5th Cir.1976), cert. denied, 429 [324]*324U.S. 1111, 97 S.Ct. 1150, 51 L.Ed.2d 566 (1977); Krizak v. W.C. Brooks & Sons, Inc., 320 F.2d 37, 42 (4th Cir.1963). This discretion is implicit in Rule 403, which provides that “[a]lthough relevant, evidence may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence.” We conclude that the district judge did not abuse his discretion.
In effect, the proffered testimony of the appellants’ expert did little more than correlate higher contracting costs with longer hauling distances. As summarized by the trial court, “the testimony of the expert boils down to, in very simple phrases, that you have a competitive advantage if you’re nearer home and that how far you want to go from your home base depends upon your willingness or the necessity to shave profits.” The court reasoned that the appellants’ expert had nothing to add to what other witnesses had already stated. We are persuaded that lay jurors were fully able to understand and appreciate the implications of the evidence admitted. Instead of assisting the jury in determining a factual issue, the proffered testimony at least amounted to unnecessary, cumulative evidence and might well have confused or misled the jury had the evidence been admitted.
IV
On a number of grounds, the appellants argue that the trial court committed reversible error in instructing the jury. We are not persuaded. Two contentions, however, deserve further comment.
First, according to Saunders and Portsmouth Paving, the court should have instructed the jury that the Government was required to prove that an overt act in furtherance of the conspiracy occurred within the five-year statute of limitations period set out by 18 U.S.C. section 3282. The proposed instruction, however, is an inaccurate statement of the law. Section 1 of the Sherman Act proscribes agreement alone, and no overt act to further the agreement need be shown. United States v. Socony-Vacuum Oil Co., 310 U.S. 150, 252, 60 S.Ct. 811, 857, 84 L.Ed. 1129 (1940); United States v. United States Gypsum Co., 600 F.2d 414, 417-18 (3d Cir.), cert. denied, 444 U.S. 884, 100 S.Ct. 175, 62 L.Ed.2d 114 (1979); United States v. Flom, 558 F.2d 1179, 1183 (5th Cir.1977). Likewise, while the Government must prove beyond a reasonable doubt that the offending agreement continued into the five-year limitations period, the Government is not required to prove a new agreement. 600 F.2d at 418.
As the Third Circuit has held, “[w]hen the conspiracy is alleged to have been formed prior to the statutory period, the issue becomes one of continuation.” Id. at 417. The evidence of that continuation may relate to something other than an overt act. To hold otherwise would produce the anomalous result of making a conviction for participation in a long-established antitrust conspiracy more difficult to procure than one based on a conspiracy conceived within five years of the date of the indictment. In the case at bar, the district court correctly instructed the jury simply that the offense charged “requires the government to prove beyond a reasonable doubt that the conspiracy existed some time during the period November 25, 1975, to November 25, 1980, and that the defendant be a member of the conspiracy during that period.”
Second, the appellants maintain that since the indictment alleged a per se violation of the Sherman Act, the trial court’s instruction describing the conspiracy charged as one that “restrained free competitive bidding” failed adequately to restrict the jury’s consideration of anticompetitive practices to those included in the indictment — bid rigging and contract allocation. While we are not persuaded that the questioned instruction is faulty, all doubt is removed when the charge to the jury is considered as a whole. See United States v. Park, 421 U.S. 658, 674-75, 95 S.Ct. 1903, 1912-13, 44 L.Ed.2d 489 (1975). In addition to the complained of instruction, the court instructed the jury that a conspiracy
[325]*325to allocate surface paving contracts and to submit rigged bids in connection with such contracts ... is the only conspiracy with which the defendants are charged, and, if you do not believe that the evidence has established beyond a reasonable doubt the existence of this conspiracy, you must find the defendants innocent.
Saunders and Portsmouth Paving further assert that the trial court’s failure to provide a definition of bid rigging was reversible error. We agree with the Government, however, that the instruction proffered by the defendants, which included in its definition of bid rigging a requirement that coconspirators agree to reciprocate by submitting complementary bids on future projects, is an erroneous statement of the law. Any agreement between competitors pursuant to which contract offers are to be submitted to or withheld from a third party constitutes bid rigging per se violative of 15 U.S.C. section 1.18 See United States v. David E. Thompson, Inc., 621 F.2d 1147, 1149-50 (1st Cir.1980); United States v. Brighton Building & Maintenance Co., 598 F.2d 1101, 1103, 1106 (7th Cir.), cert. denied, 444 U.S. 840, 100 S.Ct. 79, 62 L.Ed.2d 52 (1979); United States v. Flom, 558 F.2d 1179, 1183 (5th Cir.1977). In the instant case, the district court’s instructions satisfactorily elucidated the nature of bid rigging and the particular conspiracy for which Saunders and Portsmouth Paving were charged.
We have carefully considered the appellants’ remaining arguments and find them to be without merit. Accordingly, for the reasons stated, the judgments of conviction are affirmed.
AFFIRMED.