223 F.3d 483 (7th Cir. 2000)
Central States, Southeast and Southwest Areas  Pension Fund and Howard McDougall, Trustee, Plaintiffs-Appellees/Cross-Appellants,v.Nitehawk Express, Inc., Six Transfer, Inc.,  Interstate Express, Inc., Midwest Jobbers  Terminals, Inc. and James LaCasse, Defendants-Appellants/Cross-Appellees.
Nos. 99-2698, 99-2539 & 99-2629
In the  United States Court of Appeals  For the Seventh Circuit
Argued February 8, 2000Decided August 4, 2000

Appeals from the United States District Court  for the Northern District of Illinois, Eastern Division.  Nos. 95 C 3944 and 97 C 1402--John A. Nordberg, Judge.[Copyrighted Material Omitted]
Before Cudahy, Manion and Diane P. Wood, Circuit  Judges.
Cudahy, Circuit Judge.

I)  Background

1
In some industries, particularly those where  jobs are "episodic," individual companies do not  sponsor pension plans. See Langbein & Wolk, Pension and  Employee Benefit Law 57 (2d ed.). Instead, groups of  firms in an industry make pension contributions  to a joint, or multiemployer, pension plan. See  id. In 1980, Congress passed the Multiemployer  Pension Plan Amendments Act of 1980 (MPPAA). See  29 U.S.C. sec.sec. 1381-1461. The MPPAA was  prompted by Congress's fear that as individual  employers withdrew from joint plans without  providing funds to cover their workers' accrued  benefits, a plan could be underfunded by the time  the workers retired and their benefits came due.  See Central States, Southeast and Southwest Areas  Pension Fund and Howard McDougall v. Hunt Truck  Lines, Inc., 204 F.3d 736 (7th Cir. 2000). To  avoid the development of this scenario, Congress  provided that when an employer withdraws from a  multiemployer plan, it must pay "withdrawal  liability" in an amount roughly equal to its  proportionate share of the plan's unfunded vested  benefits. Thus, withdrawal liability essentially  forces employers to continue making payments on  behalf of fully vested workers so that, even  though the company is no longer a going concern,  its fully vested workers will receive the  benefits they earned there. The employer's  "contribution history," or the level of  contributions it has made on behalf of workers  over a fixed period of time, provides a  substantial element in the calculation of  withdrawal liability. Generally, a higher  contribution history indicates a higher  proportionate participation in a plan, but it is  not unusual in a plan where each employer sets a  different benefit level that some employers may  be paying too little for their promised benefits  while others pay too much. Therefore, until a  pension fund calculates how much a withdrawing  employer would have to invest in order to pay at  the promised benefit level, it is hard to say  whether a higher contribution history necessarily  correlates with a higher withdrawal liability.


2
James LaCasse was the 100 percent shareholder  of three companies known as Hines Transfer, Inc.  (Hines), Six Transfer Co. (Transfer) and Nitehawk  Express, Inc. (Nitehawk). The three are  considered to be a "controlled group," and are  treated as a single employer. See 29 U.S.C. sec.  1301(b)(1). We refer to the three as the LaCasse  controlled group. Transfer had eighteen workers;  Nitehawk had four. All three companies had  entered into collective bargaining agreements  with local affiliates of the International  Brotherhood of Teamsters. Under the agreements,  the companies were to make pension payments on  behalf of their workers to the Central States,  Southeast and Southwest Areas Pension Fund  (Central States), which is a multiemployer  pension plan under ERISA. See 29 U.S.C. sec.sec.  1002(37) and 1301(a)(3).


3
Hines Transfer shut down in 1986, and it was  freed from its obligation to make contributions  to Central States. Central States did not assess  withdrawal liability because the LaCasse group's  contributions to the Fund did not decline more  than 70 percent over the preceding three-year  period as a result of the Hines shutdown. See 29  U.S.C. sec. 1385. In September 1992, Transfer  sold its assets to Six Cartage (Cartage). The  MPPAA exempts some sales of assets from  withdrawal liability, if the buyers and sellers  structure the sale appropriately and comply with  certain reporting and bonding requirements. Once  the purchase agreement was complete, Transfer  notified Central States of the sale, but claimed  an exemption. Critically, Transfer did not comply  with all of the technical requirements set out in  the statute's exemption provision. Central States  did not assess withdrawal liability against Six  Transfer at that time. In any event, Cartage  continued making payments on behalf of former  Transfer employees. A year later, Nitehawk shut  down. Central States then determined that the  controlled group had completely withdrawn from  Central States, and therefore owed withdrawal  liability in the amount of $456,620. The  controlled group initiated arbitration, while  Central States exercised its statutory  prerogative to sue for so-called interim  withdrawal liability payments. See 29 U.S.C. sec.  1399(c)(2). In 1996, the district court--properly  deferring consideration of the underlying case--  granted summary judgment on the interim payment  issue for Central States, and ordered the  controlled group to pay $456,620 plus liquidated  damages and attorney's fees.


4
In 1997, the arbitrator found that the LaCasse  group owed no withdrawal liability because  Transfer's sale of assets--which accounted for  the lion's share of the group's reduced  contribution to the Fund--was exempt from  withdrawal liability under the MPPAA. See  Appellant's App. at 24 (In the Matter of  Arbitration Between Nitehawk Express and Six  Transfer, Inc. and Central States, Southeast and  Southwest Areas Pension Fund, AAA Case No. 51-  621-00147-94 at 13-14) (hereinafter In the Matter  of Nitehawk). Predictably, the LaCasse group  moved to enforce the arbitration award and vacate  the judgment ordering interim payment. The  district court determined that, contrary to the  arbitrator's view, Transfer had failed to meet  the three conditions required to secure an  exemption from withdrawal liability. Because the  sale of assets was not exempt, the court  determined, it constituted a partial withdrawal  from the Fund. Although withdrawal liability was  not proper so long as one member of the  controlled group, Nitehawk, remained a going  concern, as soon as Nitehawk shut its doors, the  controlled group had to ante up. Therefore, the  court granted partial summary judgment to Central  States and ordered the LaCasse group to pay  withdrawal liability. But it went on to hold that  the group's liability should be calculated  without reference to Transfer's contribution  history because, in its view, Cartage had  essentially adopted Transfer's contribution  history, which meant the Fund had suffered no  harm. See Central States et al. v. Nitehawk  Express, Inc. et al., No. 97 C 1402 (N.D Ill.  March 23, 1999) (hereinafter "Mem. Op.") at 15-  16. The LaCasse group appeals the award of  withdrawal liability, and Central States cross-  appeals the district court's decision to allocate  Transfer's contribution history to Cartage, as  well as its refusal to award attorney's fees in  connection with Central States' victory in the  interim payments case.1

II)  Analysis
A)  Background of the MPPAA

5
The MPPAA requires that a company choosing to  withdraw from a multiemployer pension plan must  pay "withdrawal liability," which is intended to  cover that company's share of the unfunded vested  benefits that exist when it withdraws. See 29  U.S.C. sec.sec. 1381, 1391. Congress permits  multiemployer pension plans many options for  calculating withdrawal liability, all of which  are intended to assure that departing employers  bear their fair share of pension payments, and do  not leave others holding the bag. Most of the  methods endorsed by Congress calculate withdrawal  liability "as a function of contributions made by  the withdrawing employer, normally for the five  [or ten] plan years ending with the year in which  the unfunded vested benefits or change in the  unfunded vested benefits is determined." Ronald  A. Kladder, Asset Sales After MPPAA--An Analysis  of ERISA Section 4204, 39 Bus. Law. 101, 117  (November 1983).


6
Congress recognized that the daunting prospect  of withdrawal liability might deter a struggling  company from selling a failing division and  trying to salvage the others. In order to  encourage asset sales, Congress excused companies  from withdrawal liability when they sold assets.  See 29 U.S.C. sec. 1384. But this exemption was  potentially problematic. What if the purchaser  withdrew from the plan? Because the MPPAA  calculates withdrawal fees based on a five- or  ten-year history of contributions to the Plan,  "the purchaser's withdrawal liability, calculated  as of the date of the sale, would be zero unless  the purchaser also had a preexisting contribution  obligation to the plan." See Kladder, supra, at  116.


7
To avoid the "zero liability" scenario, Congress  conditioned the seller's withdrawal exemption on  the purchaser's assumption of a preexisting  obligation to the plan. Specifically, Congress  established three conditions for exemption.  First, the buyer must assume an obligation to  make contributions to the plan at substantially  the same level as the seller's contribution. See  29 U.S.C. sec. 1384(a)(1)(A). Second, the  purchaser must provide to the plan a bond or  escrow account for five plan years commencing  with the first plan year beginning after the sale  of assets. The bond must be roughly equivalent to  the seller's annual contribution for recent  years, and will be paid to the plan if the buyer  withdraws or misses an annual contribution to the  plan at any time in the five years following the  sale. See 29 U.S.C. sec. 1384(a)(1)(B). Finally,  the contract for sale must provide that, if the  buyer fully or partially withdraws in the five  years following the sale and does not pay  withdrawal liability, the seller is secondarily  liable for the fee. See 29 U.S.C. sec.  1384(a)(1)(C).

B)  The Transfer-Cartage Sale of Assets

8
In the present case, Central States contends  that Transfer failed to obtain an exemption when  it sold its assets to Cartage. The arbitrator  found that Transfer had properly obtained an  exemption. See In the Matter of Nitehawk,  Appellant's App. at 37. The district court  disagreed. The LaCasse group urges us to defer to  the arbitrator. The district court reviewed the  arbitrator's actions for clear error, and we  apply the same standard in reviewing the district  court's decision as that court did in reviewing  the arbitrator's interpretation. See Matteson v.  Ryder Sys. Inc., 99 F.3d 108, 112 (3d Cir. 1996).  Clear error may seem an unusually exacting  standard of review for an arbitration award. It  is true that Congress specifically stated that  "there shall be a presumption, rebuttable only by  a clear preponderance of the evidence, that the  findings of fact made by the arbitrator were  correct." 29 U.S.C. sec. 1401(c).2 But we have  recognized that whether a party has successfully  structured a transaction to satisfy the statutory  standard for exemption is a "classic example[ ]  of [a] 'mixed question[ ] of law and fact.'"  Chicago Truck Drivers, Helpers and Warehouse  Workers Union (Independent) Pension Fund v. Louis  Zahn Drug Co., 890 F.2d 1405, 1409 (7th Cir.  1989). That is a particularly apt description of  the present case, in which the arbitrator was  required to compare the terms of the contract  with the statutory requirements, and to attach  legal significance to Cartage's failure to post  a bond. Congress did not set forth a standard by  which to review an arbitrator's findings on these  types of questions. We resolved in Zahn that the  proper standard of review for such questions is  for clear error. See id. at 1411. A finding is  clearly erroneous if the reviewing court, after  acknowledging that the factfinder below was  closer to the relevant evidence, is firmly  convinced that the factfinder erred. The district  court stated, and we agree, that the arbitrator  committed clear error on the question whether  Transfer's sale of assets merited an exemption.  See Mem. Op. at 11.


9
In this case, the clear error is apparent upon  review of the Purchase Agreement, the provisions  of which are fatally noncompliant with the MPPAA.  As required by statute, the purchase agreement  does seem to obligate Cartage to make payments at  substantially the same level as Transfer, thus  satisfying the first precondition for  exemption.3 But the Purchase Agreement does not  assign secondary liability to Transfer. The  LaCasse group protests that the contract  accomplishes the goal of secondary liability  because it calls for Cartage's liabilities to  revert back to it in the event of a breach. The  arbitrator agreed. See In the Matter of Nitehawk,  Appellant's App. at 36. The LaCasse group says  "reversion" is called for in sections 14 and 15  of the Agreement. Section 14 states that  covenants and warranties will survive closing,  and section 15 provides for remedies in the event  of a breach of contract. That provision states  that in the event Cartage breaches the contract,  Cartage, "at [Transfer's] option, will relinquish  all title, possession and control of the business  and all assets purchased under this agreement to  [Transfer]." Appellee's App., Tab 2 at page 10,  sec. 15(b). LaCasse testified at his deposition  that this language required him to reassume  liabilities if Cartage were to breach the  contract. Contrary to that interpretation, the  plain language does not call for an automatic  reversion to Transfer or require that Transfer  reassume liabilities. It states only that Cartage  would have to turn the business back over to  Transfer "at [Transfer's] option." Appellee's  App., Tab 2 at page 10, section 15(b) (emphasis  added). We need not speculate whether Transfer  would have exercised that potentially dubious  option if Cartage's prospects had gone south. As  discussed above, Congress did not want to leave  pension plans without recourse if buyers  "vamoosed" without paying withdrawal fees. See  Artistic Carton Company v. Paper Industry Union-  Management Pension Fund, 971 F.2d 1346, 1352-53  (7th Cir. 1992). Congress considered it crucial  that sellers be bound to pay withdrawal liability  if buyers proved unsound. The contract involved  here does not bind Transfer, and therefore the  sale of assets cannot be exempt.


10
This failure alone is enough to deprive the  asset sale of the exemption. Moreover, we note  that Transfer and Cartage bungled the bond  requirement. The arbitrator concluded that the  failure to post bond was "not determinative of  this dispute," because Central States' interests  were protected. In the Matter of Nitehawk,  Appellant's App. at 37. The district court  stated, and we agree, that this is a second  instance of clear error. As discussed above, the  purchaser must furnish a bond "commencing with"  the first plan year after the sale of assets. See  29 U.S.C. sec. 1384(a)(1)(B). This is not an  empty formality; it forces the buyer to back up  its promise to pay the seller's withdrawal  liability until the buyer accrues its own  liability. See, e.g., Artistic Carton, 971 F.2d  at 1352. (One might wonder what the buyer  receives in exchange for accepting the liability  and putting additional money down. Presumably,  the sale price for the assets reflects the  liabilities that go along with them. See, e.g.,  5 Erisa Litigation Rep. 13, 16 (April 1996) ("the  issue of additional contingent liability [if the  contribution history is to be transferred to the  buyer] can be factored into the sales price.")).  In the present case, Cartage did not post a bond.  The plan may waive the bond requirement if the  parties request a waiver and meet certain  statutory conditions, one of which is a bond  amount less than $250,000. See 29 C.F.R. sec.  4204. There is no question in this case that the  parties would have qualified for the exemption  because the amount of the required bond was less  than $250,000. But the parties erred  procedurally. First, Transfer requested the bond  exemption alone, when the statute explicitly  states that "the parties" must request a waiver.  Further, Transfer waited until six months into  the first plan year to seek the bond waiver. See  Record Vol. I at Tab 5. Transfer argues that  Cartage did not have to post the bond until the  end of the first plan year, and therefore its  waiver request was timely if filed before the  expiration of the plan year.


11
We find the waiver request inadequate. First,  Cartage did not participate in the waiver  request. This alone makes it invalid. See  Brentwood Fin. Corp. v. Western Conference of  Teamsters Pension Fund, 902 F.2d 1456, 1461 (9th  Cir. 1990) (seller's request for waiver  insufficient). And it is not as though we are  punishing Transfer for Cartage's lapse; Transfer  could probably have met the requirement of a  joint request by simply asking a Cartage official  to sign the waiver request it drafted, but it did  not. Additionally, we doubt the request was  timely. We have stated as a general matter that  the determination as to whether the purchaser has  met the requirements for an exemption is at the  time of the sale, not afterwards. See Central  States, Southeast and Southwest Areas Health and  Welfare Fund v. Cullum Companies, Inc., 973 F.2d  1333, 1338 (7th Cir. 1992). This principle pulls  us towards the Fund's view that Cartage had to  either post the bond or request the variance at  the start of the plan year.4 Transfer makes  another, more fanciful, argument, that a seller  need not satisfy the requirements for withdrawal  liability exemption until there is a complete  withdrawal. Cullum nips this argument in the bud


12
the time of sale is the time to satisfy the  requirements. In sum, we conclude that when the  LaCasse group sold Transfer's assets to Cartage,  it failed to comply with two of the three  requirements necessary to secure an exemption  from withdrawal liability.


13
The arbitrator held that the shutdowns of Hines  and Nitehawk were not sufficient to trigger  withdrawal liability because the Transfer sale  was exempt. That finding of exemption was clear  error on a mixed question of law and fact; once  it is reversed, the arbitrator's conclusion  regarding the availability of withdrawal  liability (which is probably best characterized  as a mixed question of law and fact) is also  clearly erroneous. Together, the shutdowns of  Hines, the non-exempt sale of Transfer's assets  and the shutdown of Nitehawk amounted to a  complete withdrawal from the Plan, sufficient to  trigger withdrawal liability.

C)  Apportioning Contribution History

14
The remaining question is how to apportion the  LaCasse group's contribution history among the  parties in this case. Because the arbitrator did  not think the group had withdrawn, it did not  hazard a calculation. The district court, in  granting summary judgment, deleted Transfer's  contribution history from the LaCasse group and  attributed it to Cartage.5 We review this grant  of summary judgment de novo. See Hunt Truck  Lines, 204 F.3d at 742. The most precise and  authoritative guide to allocating contribution  history in the present circumstance has been  offered by the Pension Benefit Guaranty  Corporation. As the agency charged with  interpreting the MPPAA, the PBGC is entitled to  substantial deference when it construes the  statute. See Trustees of Iron Workers Local 473  Pension Trust v. Allied Products Corp., 872 F.2d  208, 210 n.2 (7th Cir. 1989). PBGC Opinion Letters  are not as authoritative as PBGC regulations, but  they have been discussed in the same vein as  Revenue rulings. See, e.g., Blessitt v.  Retirement Plan for Employees of Dixie Engine  Co., 848 F.2d 1164, 1170-73 (11th Cir. 1988). In  PBGC Opinion Letter 92-1, the agency considered  a complex scenario in which a controlled group  like LaCasse shed four subsidiaries, each  accounting for 25 percent of the group's  contributions to a multiemployer pension plan.  See PBGC Op. Ltr. 92-1, 1992 WL 425182 (March 30,  1992) (hereinafter PBGC Letter). The PBGC's  hypothetical controlled group sold the assets of  subsidiary B in a non-exempt sale, just as  LaCasse sold the assets of Transfer. See id. at  1. The PBGC stated that "the contribution history  of [the subsidiary] remains part of the  controlled group's contribution history for  purposes of calculating amounts of subsequent  withdrawal liability." Id. at 2. Indeed, the PBGC  intimated that the only reason the sale of  subsidiary B did not trigger liability itself was  that it caused a drop of just 25 percent in the  controlled group's contributions to the Fund. See  id. In the present case, the Fund explains that  it did not view Transfer's withdrawal as causing  the required three-year drop in contributions to  qualify as a partial withdrawal. So the sale did  not--as in the PBGC hypothetical--trigger  liability. Therefore, Transfer is in exactly the  position of the PBGC's hypothetical asset seller,  and just as the contribution history remained  with the seller in that case, it must remain with  the seller in this case.


15
The district court relied on a different and,  we think, less analogous passage in the PBGC  letter to reach the opposite result. In that  passage, the PBGC instructed that if the  controlled group sold the stock of one  subsidiary, and the controlled group later  withdrew, the group's liability would be  determined without reference to the contribution  history of the subsidiary whose stock had been  sold. See id. at 3. Why? And why doesn't the same  reasoning apply to a sale of assets? The answer  is that a sale of stock is covered by a different  provision of the statute, 29 U.S.C. sec. 1398,  which specifies that the successor employer  resulting from such a transaction "shall be  considered the original employer." Therefore,  under the statute, the contribution history of a  subsidiary whose stock is sold automatically  transfers to the buyer. See PBGC Ltr. at 2-3.  This statutory dictate reflects the longstanding  principle of corporate law that "a purchaser of  corporate stock takes the risk of all outstanding  corporate liabilities, except in so far as the  contract of purchase may provide otherwise." Ford Motor Co. v. Dexter, 56 F.2d 760, 761 (2d Cir.  1932).


16
The Ninth Circuit analyzed a situation similar  to the one before us in Penn Central Corp. v.  Western Conference of Teamsters Pension Trust  Fund, 75 F.3d 529 (9th Cir. 1996). In that case,  the parent company of a controlled group shut  down two subsidiaries. It then sold the stock of  a third subsidiary. See id. at 533. Because the  stock sale caused the controlled group to cease  contributions to the Fund, withdrawal liability  was triggered. The Ninth Circuit attributed the  subsidiary's contribution history to the  purchaser. But it allocated the contribution  history for the two shuttered subsidiaries to the  seller. Id. at 533. It reasoned that when the  MPPAA equated the purchaser with the "original  employer," it meant for the purchaser to become  responsible only for the liability of the  subsidiary it bought. This result confirms our  view that the "original employer" provision for  stock sales merely codifies the principle that a  stock purchaser takes the liability associated  with that stock.


17
In the present case, Cartage did not purchase  Transfer's stock. So although the case seems  superficially analogous to Penn Central, it is  actually quite different. Under neither corporate  law nor the MPPAA did Transfer's liabilities--in  particular, its contribution history--  automatically shift to the purchaser. The MPPAA  and the PBGC's interpretations of it clearly  indicate that unless the purchaser of assets  assumes withdrawal liability by taking the  prescribed steps, the contribution history and  associated withdrawal liability stay with the  seller. So neither Penn Central nor the latter  portion of the PBGC Opinion Letter are as  instructive as the early portion of the PBGC  Opinion Letter which demonstrates that the  contribution history for a non-exempt sale of  assets remains with the seller.


18
But the district court did not rely solely on  the PBGC Opinion Letter and Ninth Circuit  opinion. The judge trusted his own eyes, and it  is much harder for us to discount his view than  it was to distinguish the authority he invoked.  At the time of the 1992 sale, Cartage was not  legally responsible6 for Transfer's pre-sale  contribution history and thus could have escaped  withdrawal liability. But by the time the case  reached Judge Nordberg in 1997, Cartage would  have been on the hook for withdrawal liability  based on the five-year contribution history it  had accrued since the purchase. The court seemed  to reason that because the Fund had suffered no  harm, it was not justified in seeking to punish  Transfer.7


19
The "no harm, no foul" approach is  instinctively appealing in the circumstances,  because a retrospective view may cast more light  on the relative rights and obligations of the  parties than would a prospective view at the time  of sale. Still, we must reject it. We have in the  past expressly refused to examine harm that  arises after a sale of assets in determining the  status of that sale. See Cullum, 973 F.2d at  1338. In Cullum, the parties completed an exempt  sale of assets, in which the buyer was obligated,  under the purchase agreement, to contribute to  the plan. See id. The buyer eventually reneged on  this obligation and the Fund assessed withdrawal  liability against the seller, reasoning that the  sale of assets was not exempt because the buyer  did not follow through on its obligation. We held  that the exempt status of the sale was to be  determined at the time of sale. See id. If the  buyer pledged to make contributions at the time  of sale, its eventual bad faith would not change  the status of the sale. The same principle that  worked to the seller's advantage in Cullum must  be applied here to the seller's detriment. At the  time of the transaction, the sale did not meet  the statutory requirements whereby Transfer's  contribution history was shifted to Cartage.  Cartage's good faith in continuing to make  contributions, thereby building up its own  history on which withdrawal liability could  eventually be calculated, does not change the  fact that the sale was not exempt. The LaCasse  group had one opportunity to discard Transfer's  contribution history--during the sale--and it did  not do so.


20
We recognize that in some circumstances,  contemporaneous analysis will look like a trap  for the unwary. But the opposite approach--asking  courts to calculate withdrawal liability  retrospectively--would force the parties to scan  a kaleidoscope, in which constantly changing  facts assume rising and falling importance until  the arbitrary moment in time when an opinion  issues. That would undermine the very certainty  the MPPAA was meant to guarantee. So we have  adopted an arguably imperfect standard in the  service of MPPAA's rules of general application  (which may ill fit, under particular  circumstances, the realities of these transient  corners of the economy). For instance, in Central  States, Southeast and Southwest Areas Pension  Fund v. Bellmont Trucking Co., 788 F.2d 428, 432  (7th Cir. 1986), we refused to excuse a bankrupt  company from withdrawal liability even though its  workers went on to retire and thus foreclose the  need for pension contributions, or went on to  obtain new jobs where the new employer paid their  contributions. We suggested that the Fund's lack  of injury was merely fortuitous, and applied a  prospective approach to withdrawal liability that  would protect the Fund in the event it was not as  lucky the next time. See id. at 432 n.2.


21
The LaCasse group urges that we have taken a  flexible line in the past in order to achieve an  equitable result, citing Central States,  Southeast and Southwest Areas Pension Fund v.  Bell Transit, 22 F.3d 706 (7th Cir. 1994). In  Bell, the employer sold its assets in an exempt  sale, and retained an amount of cash. The Fund  learned of the withheld cash, and determined that  the seller had "liquidated." Id. at 708-09. Under  the MPPAA, if the seller liquidates within five  years after the sale, it is required to post a  bond, which the seller in Bell had not done.  Because the seller had posted no bond, the Fund  tried to assess withdrawal liability against it.  We blocked this effort, stating that the Fund  should only be able to recover the bond amount  (preferably through a civil action), instead of  assessing withdrawal liability against the seller  and giving the Fund a "windfall." Id. at 712. At  first blush, it may seem that we "manipulated"  the statute in order to achieve a "fair" result.  But a close reading of Bell reveals that it was  just another application of the "contemporaneous  analysis" rule. We found that the sale was exempt  when transacted, and could not be unraveled by a  subsequent failure to post bond for the eventual  liquidation. See id. at 711-12. The LaCasse group  argues that Bell sets a precedent against "extra"  payments to the Fund. But in Bell, the Fund was  not entitled to withdrawal liability at the time  of sale, so permitting a delayed assessment of  liability would have paid to the Fund something  that was not owed. Here, the Fund was entitled to  withdrawal liability at the time of sale.


22
Ultimately, the district court seemed persuaded  by the LaCasse group's protestation that forcing  it to pay withdrawal liability would give the  Fund a "double recovery." See Mem. Op. at 13. We,  too, are troubled by the possibility that the  Fund may recover more than is required to fully  fund these workers' benefits. After all, it is  the job of courts to do justice, not make  superfluous awards as punishment for technical  errors. However, on further examination, we see  nothing at stake here to compel us to ignore the  statutory requirement that sellers meet certain  conditions to qualify for an exemption or to  ignore our own precedent assessing the validity  of an exemption at the time of sale or the PBGC's  instruction that non-exempt sellers retain their  contribution history.


23
In a pension plan, "[w]orkers' benefits may be  stated as a percentage of their highest average  incomes . . . multiplied by the number of years  of covered employment." Artistic Carton, 971 F.2d  at 1351. Multiemployer pension plans generally  employ "cliff vesting," meaning that after a  fixed number of years of service, employees gain  a nonforfeitable right to the benefits they have  accumulated. See Angell & Polk, Multi-Employer  Plans, in II Employee Benefits Law sec. 14.6 (Illinois  Institute of Continuing Legal Education, 1994).  Then, as explained in Artistic Carton, an  employee's vested benefits will continue to grow  as long as he continues to rack up additional  years of service. See 971 F.2d at 1351.  Importantly, one feature of multiemployer plans  is the "portability" of pension credits. See  Angell & Polk, supra, at sec. 14.7. This means  that a worker may leave one Plan participant and  join another, bringing with him the "years of  service" from his previous job. Withdrawing  employers stop making contributions on behalf of  employees before the employees have retired.  Withdrawal liability is supposed to represent the  amount that, "when invested, would theoretically  produce . . . a sum precisely sufficient to pay  (the employer's proportional share of) a plan's  estimated vested future benefits." Milwaukee  Brewery Workers' Pension Plan v. Jos. Schlitz  Brewing Co., 513 U.S. 414, 426 (1995). Central  States apparently bases withdrawal liability on  an employer's past ten years of contribution  history (at least that is what it did for the  LaCasse group).8 At the time of withdrawal,  some variables necessary to determining each  workers' benefits upon retirement are necessarily  unknown. For instance, the employer cannot know  how many years of service a worker will have  accrued by the time he retires or how much his  salary might rise before that time. And before  the Fund can calculate the amount of money that  must be invested today to guarantee adequate  benefits at retirement, it must discount future  benefits to their current value. The Fund has  wide discretion in adopting a valuation method,  but many such methods depend in part on current  market values, which will almost certainly  fluctuate over time. See, e.g., Masters, Mates &  Pilots Pension Plan v. USX Corp., 900 F.2d 727,  730-33 (4th Cir. 1990).


24
Based on this background, we see that the  equities of withdrawal liability are debatable in  a number of scenarios. In the paradigmatic case,  the non-exempt seller such as the LaCasse group  must pay withdrawal liability on behalf of its  employees. And a non-exempt buyer like Cartage  would have no withdrawal liability even if it  went out of business immediately. The MPPAA rules  were tailored to this circumstance, and they work  appropriately to guarantee that the Fund is  covered by the party who is equitably responsible  for the unfunded vested benefits. But the rule  leads to awkward results elsewhere. For instance,  what if a non-exempt seller were forced to pay  withdrawal liability, and the buyer in that sale  shut down only after ten years of pension  payments? The buyer would be assessed withdrawal  liability based on the ten-year contribution  history it had amassed, on top of the seller's  withdrawal liability. Therefore, both the seller  and the buyer will have made "full" withdrawal  liability payments; that is, each will have paid  the amount that, when invested, would result in  the promised benefits at retirement. But, this is  not quite the case because, after working ten  years for the second employer, the workers'  promised benefits (which are based on accrued  years of service) will be higher. Additionally,  the applicable valuation rates and actuarial  estimates may have changed in the intervening  years, as they are based in part on market  values. So in this scenario--which is essentially  the same as the dispute between the LaCasse group  and the Fund--the Fund may have recovered more  than necessary to fully fund the workers'  unfunded vested benefits. But it is difficult for  a reviewing court--not privy to the Fund's  changing valuation methods or the individual  workers' records--to know how much "excess" the  Fund stands to recover. We are left only with the  queasy feeling that by mechanically applying a  rule of general application, we may be leaving  the Fund in this instance more than whole.


25
At the same time, it would not be feasible for  us to attempt to apply some general rule of  equity to right this seeming wrong because, when  dealing with the MPPAA and the many variables  involved in calculating withdrawal liability, it  is extraordinarily hard to know what is necessary  to adequately fund the pension plan and  simultaneously do equity to the participants.  What might come to mind is some sort of  overriding rule stating that ultimately the  seller can be liable for no more than is required  to make the Fund whole. This rule might be  feasible to administer, and would place on the  Fund the burden of demonstrating the extent of  its injury, an exercise it has not attempted in  the present case. But Congress has not seen fit  to provide such a rule, and especially  considering the uncertainties involved, it is  impermissible to provide one by judicial fiat.  Whether such a rule is warranted is a policy  judgment, requiring that the possibility of  excess recovery be weighed against the need for  guaranteeing adequate funding of pensions under  all circumstances.


26
At any rate, given our reluctance to fashion  some equitable rule on our own, we find that the  potential excess recovery in this case does not  violate the MPPAA and is probably within the  bounds of equity. To the extent that the  possibility of excess recovery might offend  considerations of equity, this may be an  inescapable price Congress has elected to pay in  adopting the statutory rules. We believe that the  statute and its administrative interpretations  must continue to be refined to minimize the  chance of duplicative recoveries and other  arguable inequities. And to relieve judicial  concern about excess recovery, the Fund must be  concerned with showing the equity of its demands  as well as their conformance with the technical  requirements of the Act.

D)  Attorney's Fees

27
Finally, Central States appeals the district  court's decision to vacate the award of  attorney's fees to Central States based on the  Fund's success in securing interim payments while  the arbitration was pending. According to the  MPPAA, an employer must pay a withdrawal  liability assessment according to a schedule set  by the pension fund, "notwithstanding any request  for review or appeal of determinations of the  amount of such liability . . ." 29 U.S.C. sec.  1399(c)(2). This provision captures the MPPAA's  "pay now, arbitrate later" principle. See Central  States, Southeast and Southwest Areas Pension  Fund v. Wintz Properties, Inc., 155 F.3d 868, 872  (7th Cir. 1998). The statute further provides that  "any failure of the employer to make any  withdrawal liability payment within the time  prescribed shall be treated in the same manner as  a delinquent contribution (within the meaning of  section 1145 of this title.)" 29 U.S.C. sec.  1451(b). Finally, the statute provides that in  any action by a plan to enforce an employer's  delinquent contributions, "the court shall award  the plan" . . . "reasonable attorney's fees and  costs of the action" if the action results in a  "judgment in favor of the plan." 29 U.S.C. sec.  1132(g)(2) (emphasis added).


28
The LaCasse group argues that "no notice of a  demand for payment was ever given to Six Transfer  and therefore, it cannot be liable for interim  payments." Appellant's Br. at 19. But the notice  sent to the group upon the withdrawal of Nitehawk  states that it covers "all members of any  controlled group . . . of which [Nitehawk] is a  member." Appellee's App. at 19. Notice to one  controlled group member constitutes notice to  all. See, e.g., Central States, Southeast and  Southwest Areas Pension Fund v. Slotky, 956 F.2d  1369, 1375 (7th Cir. 1992). Further, the Fund's  extensive documentation of its liability  assessment clearly reflects that its calculations  reflected the contribution histories of Nitehawk,  Hines, and Transfer. So the LaCasse group must  have understood that it was to pay withdrawal  liability for Transfer. The LaCasse group did not  pay the liability before beginning arbitration,  and it was therefore delinquent. Section 1132  seems to us to mandate that the LaCasse group pay  the fees if Central States won a judgment on the  interim payment issue, notwithstanding the  ultimate outcome of the case. The district court  viewed the outcome of this case as a partial  victory for each side. See Appellant's App. at 21  (Order of May 19, 1999). But we have suggested  that an interim payment order was a final order  on the limited issue of which party gets to hold  the stakes during an arbitration. See Trustees of  the Chicago Truck Drivers, Helpers and Warehouse  Workers Union (Independent) Pension Fund v.  Central Transport, Inc., 935 F.2d 114, 116-17 (7th  Cir. 1991). The MPPAA's interim payment provision  reflects Congress's concern that thinly  capitalized employers who are not forced to pay  prior to arbitration may empty their pockets by  the time an arbitrator determines they owe money  to the Fund. See id. So the interim payment  accomplishes a goal entirely different from the  arbitration on the merits. As such, the Fund's  victory in securing interim payments cannot be  undone by a loss at the merits stage. Therefore,  the district court did not have discretion to  vacate the award of attorney's fees for that  portion of the litigation.

III)  Conclusion

29
In sum, we affirm the district court's finding  that the Transfer-Cartage sale did not meet  statutory requirements and therefore did not  exempt Transfer from payment of withdrawal  liability. We affirm the district court's  conclusion that when Nitehawk withdrew from  Central States, the LaCasse group effected a  complete withdrawal from the Fund. We affirm the  district court's conclusion that the assessment  of withdrawal liability against the LaCasse group  is warranted. We reverse the district court's  conclusion that Transfer's contribution history  should be excluded from the computation of the  LaCasse group's withdrawal liability, and remand  for a calculation reflecting the contribution  histories of all three employer-members of the  group. Finally, we reverse the district court's  decision to vacate the attorney's fees initially  awarded to the Fund for its success in securing  interim payments from the group, and we remand  for reimposition of an order in accord with this  opinion. Each party to bear its own costs.



Notes:


1
 Central States filed its notice of appeal June  18, giving the LaCasse group 14 days to file its  appeal. It appears the LaCasse group sent its  papers via UPS Next-Day Air on June 29, 1999. The  clerk's office inadvertently recorded receipt on  July 6, but noted the date July 1 on the check  sent with the appeal, suggesting that filing was  timely. Therefore, we reject Central States'  contention that the LaCasse group did not file  its appeal timely, and that this court does not  have jurisdiction.


2
 Notably, the standard of review for statutorily  mandated MPPAA arbitrations is not as deferential  as it is for labor arbitrations conducted  pursuant to collective bargaining agreements (the  arbitrator's award must be enforced "so long as  it draws its essence from the collective  bargaining agreement." United Steelworkers of  America v. Enterprise Wheel & Car Corp., 363 U.S.  593, 597 (1960)), or voluntary commercial  arbitrations conducted pursuant to the Federal  Arbitration Act (a district court may vacate an  arbitration award if, inter alia, "the  arbitrators exceeded their powers, or so  imperfectly executed them that a mutual, final,  and definite award upon the subject matter  submitted was not made." 9 U.S.C. sec. 10(a)(4)).  "Section 1401(b)(3) of MPPAA indicates the  Arbitration Act, which governs voluntary  arbitration, applies only to the extent it is  consistent with MPPAA . . . [T]he severely  limited review required by section 10 of the  Arbitration Act is inconsistent with section  1401(b)(2) of MPPAA, and the latter prevails."  Union Asphalts and Roadoils, Inc. v. Mo-Kan  Teamsters Pension Fund, 857 F.2d 1230, 1234 (8th  Cir. 1988).


3
 The relevant provision reads as follows
Buyer will assume all obligations of Six  Transfer, Inc. pursuant to any and all collective  bargaining agreements in effect between Six  Transfer, Inc. and Teamsters Local Union 120 of  St. Paul, Minnesota which contract covers certain  employees of Six Transfer, Inc. Buyer will also assume any and all potential  withdrawal liability to the Central States  Pension Fund into which contributions were made  pursuant to the above referenced collective  bargaining agreement with Local 120. Buyer will  continue to make payments for contributions to  the pension fund and comply with any other  obligations pursuant to the collective bargaining  agreement.
Appellee's App., Tab 2 at pages 7-8, sec. 7.


4
 The Ninth Circuit reached a similar conclusion in  a case where the seller claimed that it  "substantially satisfied" the bond requirement by  challenging withdrawal liability, thus notifying  the Fund that it was entitled to a bond waiver.  See Brentwood Fin. Corp. v. Western Conference of  Teamsters Pension Trust Fund, 902 F.2d 1456, 1461  (9th Cir. 1990). The court held that the  "practical effect" of such a course would be to  do away with the bond requirement. Here, too. If  Transfer's theory were correct, parties to a sale  could evade the bond requirement for a year.


5
 One might wonder whether the district court  should have remanded the question of allocation  to the arbitrator, and whether we should do so.  There is no clear instruction in the MPPAA. But  we have stated as a general matter that "[w]hen  possible, . . a court should avoid remanding a  decision to the arbitrator because of the  interest in prompt and final arbitration." See  Publicis Communication v. True North  Communications Inc., 206 F.3d 725, 730 (7th Cir.  2000) (quoting Teamsters Local No. 579 v. B & M  Transit, Inc., 882 F.2d 274, 278 (7th Cir. 1989)  (citations omitted). In the present case, neither  party contested the district court's authority to  decide a question left open by the arbitrator,  and both parties have briefed the issue to us. So  we think it sensible and fair to consider the  issue.


6
 When we speak of "legal responsibility," we do  not mean contractual responsibility. It is pretty  clear that the Purchase Agreement obligates  Cartage to make ongoing contributions and pay  withdrawal liability. But this obligation runs to  Transfer. Had Cartage withdrawn and declined to  pay withdrawal liability, the Fund faced  uncertain prospects for collecting from Cartage.  Cases construing the MPPAA have held that  successors in non-exempt sales may be liable for  withdrawal liability. See, e.g., Artistic Carton  Co. v. Paper Industry Union Management Pension  Fund, 971 F.2d 1346, 1352 (7th Cir. 1992). But  here a non-exempt successor has not posted a bond  and therefore the Fund would have to invest time  and money to collect the debt. And if a  "successor" suit against Cartage proved  fruitless, the Fund would have no recourse  against Transfer, which is not secondarily liable  under the Purchase Agreement. Because the Fund  would have no recourse against Transfer (this is  assuming Transfer need not pay withdrawal  liability), Transfer might well refuse to pay the  Fund. So Transfer--the only party to whom Cartage  owed a contractual duty to pay--would have no  reason to sue Cartage for damages. Consequently,  by "legal responsibility" we mean a  responsibility recognized by the MPPAA and  enforceable by the Fund.


7
 In effect, the Fund seemed to be saying, "Now we  know we didn't lose any money, so why don't you  give us some more?"


8
 Notably, if the parties had successfully  structured this as an exempt sale of assets, five  years of Transfer's contribution history on  behalf of its employees would have "vanished."  See Angell & Polk, Multi-Employer Plans, in II  Employee Benefits Law sec. 14.29(5) (Illinois  Institute of Continuing Legal Education 1994).  Though the Fund will assess liability against  Transfer for ten years of contributions, Cartage  would have adopted just five years of Transfer's  contribution history. If Cartage withdrew, it  would have owed significantly less than Transfer.


