SHEPHERD, Circuit Judge.

Appellants are five retail grocers ("the Retailers"), each attempting to bring class-action antitrust claims against one of two wholesale grocers ("the Wholesalers"). Each Retailer is a customer of only one of the Wholesalers, has an arbitration agreement with only that Wholesaler, and is attempting to use an antitrust conspiracy theory to bring suit against the Wholesaler with whom it neither does business nor has an arbitration agreement ("the non-signatory Wholesaler"). The district court dismissed the Retailers' claims and struck their allegations from the complaint in the ongoing1 lawsuit, holding that equitable estoppel bars the Retailers from bringing suit against the non-signatory Wholesaler and allows the non-signatory Wholesaler to compel arbitration. The district court certified this as a final judgment under Federal Rule of Civil Procedure 54(b). In re Wholesale Grocery Prods. Antitrust Litig., No. 09-MD-2090 ADM/AJB, 2011 WL 3837107, at *4 (D.Minn. Aug. 30, 2011) (unpublished). We have jurisdiction under 28 U.S.C. § 1291. We reverse the district court's ruling that equitable estoppel bars the Retailers from asserting antitrust claims in federal court, and we remand for further proceedings.

I.

Appellants Blue Goose Super Market, Inc. ("Blue Goose"), Millennium Operations, Inc. ("Millennium"), and King Cole Foods, Inc. ("King Cole") all have supply and arbitration agreements with Appellee SuperValu, Inc. ("SuperValu"). Appellants JFM Market, Inc. and MJF Market, Inc. (collectively "the Village Markets") both have supply and arbitration agreements with Appellee C & S Wholesale Grocers, Inc. ("C & S").2 The parties all agree that the Retailers' supply agreements with the Wholesalers do not specify price terms. Millennium's supply agreement with SuperValu specifies Millennium will purchase a certain percentage of its requirements from SuperValu. The other Retailers' supply agreements do not contain requirements provisions, but rather generally state that the Wholesaler named in the agreement will make products available and that the Retailer named in the agreement will pay the prices stated on any future sales documents. The arbitration agreements accompanying3 the supply agreements all generally specify that the signatories will arbitrate any disputes between them.

In September 2003, C & S and SuperValu entered into an Asset Exchange Agreement ("AEA") in which they exchanged certain business assets, including some customer contracts, and agreed not to do business with or solicit any of the exchanged customers for a certain time period. Some, but not all, of the Retailers' supply and arbitration agreements were among the contracts exchanged as part of the AEA.

After the AEA, all of the Retailers purchased goods from the Wholesaler with whom they had a supply and arbitration agreement ("the signatory Wholesaler"). Each Retailer subsequently brought class-action antitrust claims in federal district court. In an effort to avoid arbitration, each Retailer brought claims only against the Wholesaler with whom they did not have a supply and arbitration agreement. Thus, Blue Goose, Millennium, and King Cole, who had contracts and did business only with SuperValu during the class period, brought antitrust claims only against C & S. Likewise, the Village Markets, who had contracts and did business only with C & S during the class period, brought antitrust claims only against SuperValu. The Retailers alleged that the AEA amounted to an illegal antitrust conspiracy between the Wholesalers in violation of the Sherman Act, 15 U.S.C. § 1, artificially inflating prices and causing each Retailer to overpay for their wholesale grocery purchases.

The Wholesalers moved to dismiss the Retailers' antitrust claims. The Wholesalers argued that the doctrine of either equitable estoppel or successor-in-interest allowed the non-signatory Wholesaler to enforce the signatory Wholesaler's arbitration agreements with the Retailers, thus requiring the Retailers to arbitrate their antitrust claims against the non-signatories. The Retailers responded that neither the equitable estoppel doctrine nor the successor-in-interest doctrine compelled them to arbitrate, and further argued that even if one of those doctrines did apply, the arbitration agreements were unenforceable for public policy reasons.

The district court granted the Wholesalers' motion to dismiss the Retailers' claims from the putative class action. In re Wholesale Grocery Prods. Antitrust Litig., No. 09-MD-2090 ADM/AJB, slip op. at 11, 2011 WL 9558054 (D.Minn. July 5, 2011). First, the court held that the non-signatory Wholesaler could invoke equitable estoppel to compel the Retailers to arbitrate their antitrust claims. Id. at 6. Second, the court held that the arbitration agreements were enforceable. Id. at 10. Because the district court held the Wholesalers could use equitable estoppel to compel arbitration, the court did not address the Wholesalers' argument that they could enforce the arbitration agreements as successors-in-interest. The Retailers brought the present appeal.

II.

A.

The first issue on appeal is whether the non-signatory Wholesalers can use equitable estoppel to compel the Retailers to arbitrate their antitrust claims. "Where a district court grants arbitration, its application of equitable estoppel presents at least mixed questions of law and fact. In this circuit, mixed questions of law and fact are reviewed de novo." Donaldson Co. v. Burroughs Diesel, Inc., 581 F.3d 726, 731 (8th Cir.2009). Upon de novo review, we hold that the non-signatory Wholesalers cannot use equitable estoppel to compel arbitration.

As a preliminary matter, "state contract law governs the ability of nonsignatories to enforce arbitration provisions." PRM Energy Sys., Inc. v. Primenergy, L.L.C., 592 F.3d 830, 833 (8th Cir.2010) (internal quotation marks omitted). The parties agree that Minnesota law applies here.4 The only Minnesota Supreme Court case mentioning equitable estoppel in the arbitration context is Onvoy, Inc. v. SHAL, LLC, 669 N.W.2d 344 (Minn.2003). In that case, the court stated the general rule that "arbitration clauses are contractual and cannot be enforced by persons who are not parties to the contract." Id. at 356. The court then explained that equitable estoppel is an exception to the rule and "prevents a signatory from relying on the underlying contract to make his or her claim against the nonsignatory." Id. The court did not reach the issue of whether equitable estoppel applied, however, because it remanded the case on other grounds. Id. at 357. One unpublished Minnesota Court of Appeals case has evaluated when equitable estoppel applies in the arbitration context,5 but Minnesota law specifies that unpublished cases are not precedential. Minn.Stat. § 480A.08(3)(c). Minnesota appears to follow federal law regarding equitable estoppel. See Onvoy, 669 N.W.2d at 356 ("Federal cases have set out at least three principles on which a nonsignatory to a contract can compel arbitration: equitable estoppel, agency, and third-party beneficiary." (citing MS Dealer Serv. Corp. v. Franklin, 177 F.3d 942, 947 (11th Cir.1999), abrogated on other grounds by Arthur Andersen LLP v. Carlisle, 556 U.S. 624, 631, 129 S.Ct. 1896, 173 L.Ed.2d 832 (2009))). Since we do not have any published Minnesota cases applying equitable estoppel, and since Minnesota appears to follow federal law regarding equitable estoppel, we look to federal law here.6

We addressed the doctrine of equitable estoppel in PRM Energy Systems. In that case, we explained:

PRM Energy Sys., 592 F.3d at 835 (footnote added). A non-signatory can "force a signatory into arbitration under the [equitable] estoppel theory when the relationship of the persons, wrongs and issues involved is a close one." CD Partners, LLC v. Grizzle, 424 F.3d 795, 799 (8th Cir.2005). For example, as relevant to the instant case, equitable estoppel applies when a complaint involves "allegations of pre-arranged, collusive behavior demonstrating that the claims are intimately founded in and intertwined with the agreement at issue." PRM Energy Sys., 592 F.3d at 835 (internal quotation marks omitted). In contrast, merely alleging that a non-signatory conspired with a signatory is insufficient to invoke equitable estoppel, absent some "intimate[] ... and intertwined" relationship between the claims and the agreement containing the arbitration clause. PRM Energy Systems, 592 F.3d at 835.

Examining the facts of cases applying our equitable estoppel test is instructive. First, in CD Partners, CDWI and C.D. Partners signed franchise agreements containing arbitration clauses. 424 F.3d at 797. C.D. Partners later sued three of CDWI's chief executives for negligence, negligent misrepresentation, and fraudulent misrepresentation in connection with their operation of the franchises. Id. The three executives moved to compel arbitration, and the district court denied their motion. Id. at 798. We reversed, holding, in relevant part, that the "dispute between signatory C.D. Partners and [the three non-signatory chief executives] arises out of and relates directly to the contractual agreement between the signatories, where the core of the dispute is the conduct of the three nonsignatories in fulfilling signatory CDWI's promises." Id. at 800.

Second, in PRM Energy Systems, PRM had a contract with Primenergy that granted Primenergy a license to use some of PRM's technology and also allowed Primenergy to enter into sublicense agreements with third parties. 592 F.3d at 832. The contract contained an arbitration clause. Id. Primenergy allegedly conspired with a third party, the Japan-based company Kobe Steel, to violate the terms of that contract. Id. More specifically, although the contract specified Primenergy could not sublicense PRM's technology to companies in Japan, Primenergy and Kobe Steel allegedly entered into such a sublicense agreement. Id. PRM brought suit against non-signatory Kobe Steel for tortious interference and conspiracy, and Kobe Steel moved to compel arbitration. Id. at 833. The district court granted Kobe Steel's motion on the basis of equitable estoppel, and we affirmed. Id. We explained that equitable estoppel applied because the case involved allegations of violation of the terms of the agreement containing the arbitration clause, and because that agreement "anticipated that an entity such as Kobe Steel might enter into a licensing relationship with Primenergy, and the [agreement] attempted to govern that expected relationship." Id. at 836.

Applying this precedent, we hold that the Retailers' claims against the non-signatory Wholesalers are not "so intertwined with the agreement containing the arbitration clause that it would be unfair to allow the signatory to rely on the agreement in formulating its claims but to disavow availability of the arbitration clause of that same agreement." Id. at 835. In both PRM Energy Systems and CD Partners, the plaintiffs' claims arose directly from violations of the terms of a contract containing an arbitration clause. See PRM Energy Sys., 592 F.3d at 832-33; CD Partners, 424 F.3d at 797. Without the contracts in those cases, the plaintiffs would not have had a cause of action. In contrast, the Retailers are bringing antitrust conspiracy claims against the non-signatory Wholesalers. These statutory claims exist independent of the supply and arbitration agreements. See 15 U.S.C. § 1 ("Every ... conspiracy[] in restraint of trade or commerce among the several States, or with foreign nations, is declared to be illegal."); 15 U.S.C. § 15 ("[A]ny person who shall be injured in his business or property by reason of anything forbidden in the antitrust laws may sue therefor...."). Moreover, the Retailers' antitrust claims are premised on paying artificially inflated prices, but since none of the Retailers' contracts with the Wholesalers specify price terms, the Retailers' claims do not involve alleged violation of any terms of those contracts. Nor is there any evidence, as there was in PRM Energy Systems, that the contracts explicitly anticipated a signatory would enter into the type of relationship with a non-signatory — here, the relationship being that of antitrust co-conspirators — that ultimately gave rise to the claims. Under these circumstances, we cannot say that the Retailers' claims "rely on"8 and have an "intimate[] ... and intertwined" relationship with the contracts such that equitable estoppel should apply. See PRM Energy Sys., 592 F.3d at 835 (internal quotation marks omitted).

In holding that equitable estoppel permits the non-signatory Wholesaler to compel arbitration here, the district court reasoned, "The agreements to arbitrate ... are a fundamental component of the entire wholesaler-retailer relationship between the signatories.... This is precisely the relationship that is at issue in this litigation." In re Wholesale Grocery Prods. Antitrust Litig., No. 09-MD-2090 ADM/AJB, slip op. at 6, 2011 WL 9558054 (D.Minn. July 5, 2011). The court further reasoned that "the existence of the agreements to arbitrate is presumed by the claims asserted by the [Retailers] because without the agreements no wholesaler-supplier relationship would exist to be exploited by the alleged anti-trust conspiracy...." Id. at 7. This analysis, however, focuses too much on the relationship between the signatories, rather than on the relationship between the signatory's claims against the non-signatory and the contract containing the arbitration clause.9 As explained above, these antitrust conspiracy claims do not involve violation of the terms of the contract, the face of the contract does not provide the basis for the alleged injuries, and there is no evidence that the contract anticipated the precise type of relationship giving rise to the claims. Thus, the requisite relationship is lacking here.

B.

Although we hold that the non-signatory Wholesalers cannot use equitable estoppel to compel the Retailers to arbitrate their antitrust claims, this does not fully resolve the question of whether the non-signatory Wholesalers can compel any of the Retailers to arbitrate. The non-signatory Wholesalers also argue they can enforce Millennium's and the Village Market's arbitration agreements as successors-in-interest because those agreements were exchanged as part of the AEA.10 Since the district court found the equitable estoppel issue dispositive, it did not address the successor-in-interest argument. Accordingly, we remand for the district court to consider this argument in the first instance. See Alliant Techsystems, Inc. v. Marks, 465 F.3d 864, 873 (8th Cir.2006) ("Because the district court did not decide the merits of these claims, which are heavily fact-based, we decline to consider them in the first instance.").

C.

Finally, King Cole and the Village Markets argue that even if the non-signatory Wholesaler can compel arbitration, the arbitration agreements are unenforceable for public policy reasons.11 With respect to King Cole, this argument is moot because we have held that C & S cannot use equitable estoppel to compel arbitration, and C & S does not make the alternative argument that it can enforce the arbitration agreement as a successor-in-interest. With respect to the Village Markets, this argument is relevant only if the district court finds that SuperValu can enforce the arbitration agreement as a successor-in-interest. Since we are remanding for the district court to consider the successor-in-interest argument, we decline to reach the Village Markets' public policy argument as we would risk issuing an advisory opinion. See United States v. Tyerman, 641 F.3d 936, 936 n. 2 (8th Cir.2011) (declining to reach remaining issues "because it is unknown if and how this case will proceed on remand").

III.

Accordingly, we reverse the district court's holding that the non-signatory Wholesalers can enforce the Retailers' arbitration agreements based on the doctrine of equitable estoppel. We remand for further proceedings consistent with this opinion.

BENTON, Circuit Judge, dissenting.

Because Minnesota equitable-estoppel law and the text of the arbitration agreements compel arbitration, I respectfully dissent from the court's opinion. The opinion has two, independent, flaws. First, the court misreads the arbitration agreement. Second, the court incorrectly applies choice-of-law principles, thereby omitting an important component of equitable-estoppel doctrine in Minnesota.

I.

The court asserts that this court's precedents preclude equitable estoppel, ante at 922-24, citing PRM Energy Sys., Inc. v. Primenergy, L.L.C., 592 F.3d 830, 833 (8th Cir.2010); CD Partners, LLC v. Grizzle, 424 F.3d 795, 799 (8th Cir.2005). The court correctly describes the factual circumstances of PRM Energy and CD Partners. The lynchpin of this court's holding here, however, is that the Retailers' claims "exist independent of the supply and arbitration agreements," ante at 923. That statement has no basis in the record, misreads the arbitration agreement, and leads to an incorrect result in this case.

The arbitration agreements in this case apply to any dispute arising between the parties, not solely those arising under a single contract:

Although executed on the same date as the Retail Agreements, the arbitration agreement is a separate document. It does not make any reference to the Retail Agreement. By its terms, it applies to any dispute between the parties, whether or not it involves the Retail Agreement. Nevertheless, the court apparently concludes that this arbitration agreement is limited to disputes under the Retail Agreement.

This arbitration agreement is not like the arbitration clauses in PRM Energy and CD Partners. There, the arbitration clauses applied only to disputes related to the contract containing the clause. PRM Energy, 592 F.3d at 837 (Beam, J., dissenting) ("The arbitration clause tangentially at issue here purports to cover `all disputes arising under' a technology licensing agreement between PRM and Primenergy."); CD Partners, 424 F.3d at 797 ("Each franchise agreement contained an identical arbitration clause which stated, in relevant part: `Except as provided in this Agreement, Franchisor and Franchisee agree that any claim, controversy or dispute arising out of or relating to Franchisee's operation of the Franchised business under the Agreement ... which cannot be amicably settled shall be referred to Arbitration....'"). The arbitration clauses in both cases were limited to disputes arising under a specific contract. Therefore, the appropriate inquiry for equitable estoppel was whether the claims were sufficiently "intertwined" with the contract. See PRM Energy, 592 F.3d at 835.

Not so in this case. The arbitration agreement here covers all disputes "including but not limited to those arising out of or relating to any agreement between the parties." As the district court correctly ruled, this arbitration agreement covers the entire relationship and course of dealing, and would include, for example, later purchase contracts and purchase transactions. The antitrust claims from the Retailers — that purchase prices were inflated — are certainly "intertwined" with and "rely on" the terms of those transactions and the course of dealing between the parties. See id.

The court states: "In both PRM Energy Systems and CD Partners, the plaintiffs' claims arose directly from violations of the terms of a contract containing an arbitration clause," ante at 923. Precisely. This case presents a broader arbitration agreement that is not tied solely to claims arising under a specific contract. Yet the court treats them the same. I would hold that the arbitration agreement here compels arbitration based on equitable estoppel.

II.

The court correctly notes that state law determines whether nonsignatories can enforce arbitration provisions. PRM Energy, 592 F.3d at 833 (8th Cir.2010), citing Arthur Andersen LLP v. Carlisle, 556 U.S. 624, 630-31, 129 S.Ct. 1896, 173 L.Ed.2d 832 (2009). Minnesota has recognized equitable estoppel as one method to enforce an arbitration agreement against a nonsignatory. Onvoy, Inc. v. SHAL, LLC, 669 N.W.2d 344, 356 (Minn.2003), citing MS Dealer Serv. Corp. v. Franklin, 177 F.3d 942, 947 (11th Cir.1999), abrogated on other grounds by Carlisle, 556 U.S. at 631, 129 S.Ct. 1896. The Minnesota Supreme Court's only discussion of equitable estoppel — in its entirety — is as follows:

Id. Not in Onvoy — or in any other case — does the Minnesota Supreme Court apply equitable estoppel, announce the appropriate test(s) for it, or provide any further insight into Minnesota equitable-estoppel law. Nevertheless, this court holds that "Minnesota appears to follow federal law regarding equitable estoppel," ante at 927.

Because the Minnesota Supreme Court has not addressed how to apply equitable estoppel, this court must predict how the court would rule. Progressive N. Ins. Co. v. McDonough, 608 F.3d 388, 390 (8th Cir.2010) ("If the highest state court has not decided an issue we must attempt to predict how the highest court would resolve the issue, with decisions of intermediate state courts being persuasive authority."). Based on the discussion in Onvoy, the only appropriate prediction is that the Minnesota Supreme Court would apply equitable estoppel as expressed in MS Dealer — the only case that court cites.

MS Dealer articulates two separate inquiries for equitable estoppel. "First, equitable estoppel applies when the signatory to a written agreement containing an arbitration clause `must rely on the terms of the written agreement in asserting [its] claims' against the nonsignatory." MS Dealer, 177 F.3d at 947 (alteration in original), quoting Sunkist Soft Drinks, Inc. v. Sunkist Growers, Inc., 10 F.3d 753, 757 (11th Cir.1993). "Second, `application of equitable estoppel is warranted ... when the signatory [to the contract containing the arbitration clause] raises allegations of... substantially interdependent and concerted misconduct by both the nonsignatory and one or more of the signatories of the contract.'" Id. (alterations in original), quoting Boyd v. Homes of Legend, Inc., 981 F.Supp. 1423, 1432 (M.D.Ala. 1997).

Further, the one Minnesota case applying equitable estoppel is dispensed with by the court because it is unpublished and therefore "not precedential," ante at 921-22 & n. 5, citing ev3, Inc. v. Collins, No. A08-1816, A08-1901, 2009 WL 2432348, at *1 (Minn.Ct.App. Aug. 11, 2009) (unpublished); Minn.Stat. § 480A.08(3)(c). While it may not be precedential, it provides a persuasive indication of how the Minnesota Supreme Court would apply equitable estoppel. See Marvin Lumber & Cedar Co. v. PPG Indus., Inc., 223 F.3d 873, 888 (8th Cir.2000) (relying, in part, on an unpublished Minnesota Court of Appeals case to justify a predicted outcome of the Minnesota Supreme Court); Friedberg v. Chubb & Son, Inc., 832 F.Supp.2d 1049, 1059 n. 7 (D.Minn.2011) ("Bloom [v. Western Nat. Mut. Ins. Co., 2006 WL 1806415 (Minn.App.)] is an unpublished opinion of the Minnesota Court of Appeals, but the court finds Bloom persuasive in predicting how the Minnesota Supreme Court would interpret the instant policy."). The Minnesota Court of Appeals followed the exact approach I suggest — equitable estoppel as articulated in MS Dealer. ev3, 2009 WL 2432348, at *3 ("[I]n MS Dealer Serv. Corp. v. Franklin, cited by the supreme court in Onvoy, the Eleventh Circuit stated that equitable estoppel allows a nonsignatory to compel arbitration in two different situations...."); see also In re Petters Co., Inc., 480 B.R. 346, 361-62 (Bankr.D.Minn.2012) (explaining that Minnesota courts have adopted these two, separate inquiries for equitable estoppel).

The "relies on" test and the "concerted misconduct" test are separate grounds for equitable estoppel in Minnesota. Under either test, I believe equitable estoppel compels arbitration of the claims in this case.

As discussed in Part I, the Retailers' claims rely on the course of dealing between the parties and the purchase transactions — all of which are governed by the arbitration agreement. But the court's analysis should not stop there.

This court should also consider the "concerted misconduct" test of equitable estoppel. See MS Dealer, 177 F.3d at 947. The court claims to have addressed concerted misconduct by discussing PRM Energy and CD Partners because "in both PRM Energy Systems and CD Partners, we relied heavily on MS Dealer," ante at 924 n. 8. Even so, this court should be concerned with what the Minnesota Supreme Court's view would be, and not what this court's interpretation has been. See McDonough, 608 F.3d at 390.

The Minnesota Court of Appeals held that concerted misconduct is grounds for equitable estoppel. ev3, 2009 WL 2432348, at *6. This test is met when the plaintiff alleges "substantially interdependent and concerted misconduct by both the nonsignatory and one or more of the signatories of the contract." MS Dealer, 177 F.3d at 947. That is what happened here. The Retailers allege that SuperValu and C & S acted in concert through the Asset Exchange Agreement to establish separate territories, eliminate competition, and raise prices.

The PRM Energy case supports this conclusion: "PRM specifically allege[d] coordinated behavior between a signatory and a non-signatory" and "[c]ollusive conduct between Kobe Steel and Primenergy allegedly arose from this potential relationship." PRM Energy, 592 F.3d at 836. Further, even if concerted misconduct requires the claims to be intertwined with the contract(s) subject to arbitration, that nexus is present, as discussed in Part I.

I would hold that the concerted misconduct alleged in this case also establishes equitable estoppel and compels arbitration.

III.

Finding that equitable estoppel compels arbitration would require this court to address King Cole's and the Village Markets' argument that the arbitration agreements are unenforceable on public-policy grounds because arbitration would be prohibitively expensive. This argument is foreclosed by the Supreme Court. AT & T Mobility LLC v. Concepcion, ___ U.S. ___, 131 S.Ct. 1740, 1748, 179 L.Ed.2d 742 (2011). But see In re Am. Express Merchants' Litig., 667 F.3d 204, 217-18 (2d Cir.), cert. granted sub nom. Am. Express Co. v. Italian Colors Restaurant, ___ U.S. ___, 133 S.Ct. 594, 184 L.Ed.2d 390 (2012).

* * * * * *

I respectfully dissent from the court's opinion, and would affirm the judgment of the district court.