Choi v. Tower Rsch. Cap. LLC ( 2021 )


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  • 20-1648-cv
    Choi v. Tower Rsch. Cap. LLC
    In the
    United States Court of Appeals
    For the Second Circuit
    ________
    AUGUST TERM, 2020
    ARGUED: MAY 18, 2021
    DECIDED: JUNE 22, 2021
    No. 20-1648-cv
    MYUN-UK CHOI, JIN-HO JUNG, SUNG-HUN JUNG, SUNG-HEE LEE, and
    KYUNG-SUB LEE, individually and on behalf of all others similarly
    situated,
    Plaintiffs-Appellants,
    v.
    TOWER RESEARCH CAPITAL LLC, MARK GORTON,
    Defendants-Appellees. *
    ________
    Appeal from the United States District Court
    for the Southern District of New York.
    ________
    Before: WALKER, PARK, and NARDINI, Circuit Judges.
    ________
    * The Clerk of Court is respectfully requested to amend the official
    caption as set forth above.
    2                                                        No. 20-1648-cv
    Plaintiffs, five South Korean citizens, traded a derivative
    financial product called KOSPI 200 futures on an overnight market of
    the Korea Exchange (KRX).          They brought this action against
    defendants Tower Research Capital LLC (Tower) and its CEO, Mark
    Gorton, alleging that, in 2012, Tower’s trading of KOSPI 200 futures
    violated the anti-manipulation provisions of the Commodity
    Exchange Act (CEA). Following an initial appeal in which we rejected
    Tower’s extraterritoriality defense, the district court (Kimba Wood, J.)
    entered summary judgment on plaintiffs’ CEA claims, finding that
    Tower’s overnight trading of KOSPI 200 futures was not “subject to
    the rules of [a] registered entity” as required by Section 9 of the CEA.
    Plaintiffs appeal the judgment of the district court, arguing
    that: (1) there is a genuine factual dispute as to whether Tower’s
    trading was subject to the rules of the Chicago Mercantile Exchange
    (CME), a “registered entity” under the CEA; (2) the district court
    abused its discretion by excluding the report of their expert; (3) the
    judgment    contradicts    our    prior     opinion   denying   Tower’s
    extraterritoriality defense, and therefore violates the law of the case;
    and (4) the judgment will undermine public policy by placing trading
    of foreign futures in the United States beyond the reach of the CEA.
    For the reasons that follow, we find plaintiffs’ contentions without
    merit and therefore AFFIRM the judgment of the district court.
    ________
    MICHAEL B. EISENKRAFT (Richard A. Speirs, Jessica
    (Ji Eun) Kim, on the brief), Cohen Milstein Sellers &
    Toll PLLC, New York, New York; Dan S.
    Sommers, on the brief, Cohen Milstein Sellers & Toll
    PLLC, Washington, District of Columbia; for
    Plaintiffs-Appellants Myun-Uk Choi, et al.
    3                                                        No. 20-1648-cv
    NOAH A. LEVINE, Wilmer Cutler Pickering Hale
    and Dorr LLP, New York, New York; Matthew T.
    Martens, Matthew Beville, Albinas J. Prizgintas, on
    the brief, Wilmer Cutler Pickering Hale and Dorr
    LLP, Washington, District of Columbia; Adam
    Cambier, on the brief, Wilmer Cutler Pickering Hale
    and Dorr LLP, Boston, Massachusetts; for
    Defendants-Appellees Tower Research Capital LLC and
    Mark Gorton.
    ________
    JOHN M. WALKER, JR., Circuit Judge:
    Plaintiffs, five South Korean citizens, traded a derivative
    financial product called KOSPI 200 futures on an overnight market of
    the Korea Exchange (KRX).          They brought this action against
    defendants Tower Research Capital LLC (Tower) and its CEO, Mark
    Gorton, alleging that, in 2012, Tower’s trading of KOSPI 200 futures
    violated the anti-manipulation provisions of the Commodity
    Exchange Act (CEA). Following an initial appeal in which we rejected
    Tower’s extraterritoriality defense, the district court (Kimba Wood, J.)
    entered summary judgment on plaintiffs’ CEA claims, finding that
    Tower’s overnight trading of KOSPI 200 futures was not “subject to
    the rules of [a] registered entity” as required by Section 9 of the CEA.
    Plaintiffs appeal the judgment of the district court, arguing
    that: (1) there is a genuine factual dispute as to whether Tower’s
    trading was subject to the rules of the Chicago Mercantile Exchange
    (CME), a “registered entity” under the CEA; (2) the district court
    abused its discretion by excluding the report of their expert; (3) the
    judgment    contradicts    our    prior     opinion   denying   Tower’s
    extraterritoriality defense, and therefore violates the law of the case;
    and (4) the judgment will undermine public policy by placing trading
    of foreign futures in the United States beyond the reach of the CEA.
    4                                                             No. 20-1648-cv
    For the reasons that follow, we find plaintiffs’ contentions without
    merit and therefore AFFIRM the judgment of the district court.
    BACKGROUND
    We draw our discussion of the facts from plaintiffs’ second
    amended complaint 1 as well as exhibits and other evidence submitted
    in connection with defendants’ motion for summary judgment.
    Unless otherwise noted, the facts are undisputed and construed in the
    light most favorable to plaintiffs.
    The KOSPI 200 is an index of two hundred Korean stocks
    traded on the KRX, a securities and derivatives exchange
    headquartered in Busan, South Korea. To allow investors to take
    positions on future values of the KOSPI 200 index, the KRX created a
    derivative financial product called KOSPI 200 futures contracts. 2
    During daytime hours, orders for KOSPI 200 futures are placed and
    matched on the KRX in South Korea. During overnight hours, orders
    for KOSPI 200 futures are placed on the KRX in South Korea but
    matched with a counterparty through an electronic platform called
    CME Globex in Aurora, Illinois. 3 Following matching, all trades—
    including those placed overnight—are settled on the KRX.
    Unlike the KRX, CME Globex is not an exchange. Rather, it is
    an electronic platform that provides a trade-matching engine used by
    a number of exchanges—both foreign and domestic. Notably, CME
    Globex is owned by CME Group Inc. (CME Group), a holding
    1 See J. App. at 92–124 (second amended complaint, hereinafter referred
    to as “SAC”).
    2 A futures contract is an agreement to purchase or sell a particular asset
    on a later date at a predetermined price. See Set Capital LLC v. Credit Suisse
    Grp. AG, 
    996 F.3d 64
    , 69 n.3 (2d Cir. 2021).
    3 The KRX’s overnight hours are 5:00 p.m. to 6:00 a.m. Seoul time, or 2:00
    a.m. to 3:00 p.m. Chicago time.
    5                                                            No. 20-1648-cv
    company that also owns several domestic exchanges, including the
    CME, the Chicago Board of Trade (CBOT), the New York Mercantile
    Exchange (NYMEX), and the Commodity Exchange (COMEX). Like
    the KRX, all four of these exchanges use CME Globex to match trades
    of their own exchange’s futures contracts.
    In 2012, defendant Tower, a high-frequency trading firm in
    New York, executed nearly 4,000,000 trades for KOSPI 200 futures
    during the KRX’s overnight hours—representing approximately
    53.8% of all overnight KOSPI 200 futures trades for the entire calendar
    year. Plaintiffs, who also traded KOSPI 200 futures, allege that many
    of these trades were manipulative. Specifically, plaintiffs allege that
    Tower’s traders placed large volume buy or sell orders on the KRX
    overnight market and then used Tower’s algorithmic and high-speed
    trading technology to immediately cancel their orders or to fill their
    own orders before they could be matched by other traders. Tower
    employed these tactics because its intent was not to execute the trades
    with a counterparty, but rather to create a false impression of supply
    and demand and, in turn, artificially drive the market price up or
    down. 4 Plaintiffs allege that, once the market price moved in the
    desired direction, Tower sold futures contracts at the artificially
    inflated price or bought futures contracts at the artificially deflated
    price, earning more than $14,000,000 in illicit profits.
    In May 2014, South Korean regulators announced that they had
    uncovered potentially unlawful trading in the overnight market for
    4Plaintiffs describe aspects of Tower’s scheme as a type of “spoofing.”
    SAC ¶ 63. While the term “spoofing” has acquired various meanings over
    the years, see United States v. Wedd, 
    993 F.3d 104
    , 110 n.2 (2d Cir. 2021), in
    the context of commodities trading fraud it generally refers to the
    manipulative practice of “bidding or offering with the intent to cancel the
    bid or offer before execution,” 7 U.S.C. § 6c(a)(5)(C) (defining “spoofing”
    under the Commodity Exchange Act).
    6                                                           No. 20-1648-cv
    KOSPI 200 futures and that they had referred Tower to South Korean
    prosecutors.    Several months later, plaintiffs initiated the instant
    litigation, filing a class-action complaint on behalf of themselves and
    others who were allegedly harmed by Tower’s manipulative scheme.
    The complaint asserted causes of action for violations of the CEA and
    New York common law.
    In March 2015, defendants moved to dismiss the complaint on
    the basis that Tower’s alleged conduct occurred in South Korea and
    so was not within the territorial reach of the CEA. The district court
    granted the motion in February 2016, holding that applying the CEA
    to Tower’s conduct would be impermissibly extraterritorial under
    Morrison v. National Australia Bank Ltd.5 The district court granted
    plaintiffs leave to amend their complaint, but later dismissed their
    amended complaint on the same basis in February 2017. 6 According
    to the district court, the amended complaint still failed to allege either
    that CME Globex was a domestic exchange or that Tower’s trades
    were domestic transactions, at least one of which was required to
    establish domestic application under Morrison. 7
    In March 2018, we vacated the dismissal and remanded for
    5See Myun-Uk Choi v. Tower Rsch. Cap. LLC (Choi I), 
    165 F. Supp. 3d 42
    ,
    48–50 (S.D.N.Y. 2016) (citing Morrison, 
    561 U.S. 247
    , 269–70 (2010)).
    6 See Myun-Uk Choi v. Tower Rsch. Cap. LLC (Choi II), 
    232 F. Supp. 3d 337
    ,
    340–43 (S.D.N.Y. 2017).
    7 
    Id.
     In Morrison, the Supreme Court concluded that Section 10(b) of the
    Securities Exchange Act, 15 U.S.C. § 78j(b), reaches “only transactions in
    securities listed on domestic exchanges” and “domestic transactions in
    other securities.” 
    561 U.S. at 267
    . We held in Loginovskaya v. Batratchenko
    that Morrison’s “domestic transaction” test applies to the CEA, 
    764 F.3d 266
    ,
    272–75 (2d Cir. 2014), but we have not had occasion to decide whether
    Morrison’s “domestic exchange” test applies to the CEA as well.
    7                                                           No. 20-1648-cv
    further proceedings. 8 Applying Morrison and more recent circuit
    precedent, we held that plaintiffs’ allegations made it plausible that
    parties who trade KOSPI 200 futures on the KRX overnight market
    incur irrevocable liability in the United States, where their orders are
    matched through CME Globex. 9            At the pleadings stage, those
    allegations were sufficient to show that Tower’s trades were plausibly
    “domestic transactions” under Morrison such that applying the CEA
    to Tower’s conduct would not constitute an extraterritorial
    application of the Act. 10 Because our irrevocable liability analysis was
    a sufficient basis to resolve the extraterritoriality question, we
    declined to address whether the CEA could reach Tower’s conduct on
    the basis that CME Globex is a “domestic exchange.” 11
    In July 2018, following remand to the district court, defendants
    again moved to dismiss plaintiffs’ CEA claims, this time raising a
    factual defense: Even if the CEA could apply to Tower’s trading
    without running afoul of Morrison, its trading of KOSPI 200 futures
    was not “subject to the rules of any registered entity” as required by
    the CEA itself. 12 The district court referred the motion to a magistrate
    judge, who granted plaintiffs leave to amend their complaint in
    response to the motion. In May 2019, plaintiffs filed a second
    amended complaint alleging that Tower’s trading of KOSPI 200
    futures was subject to the rules of the CME, one of four registered
    entities owned by CME Group.
    After the close of fact discovery, defendants moved for
    judgment on the pleadings or, in the alternative, for summary
    judgment, maintaining that Tower’s trading of KOSPI 200 futures was
    8See Myun-Uk Choi v. Tower Rsch. Cap. LLC (Choi III), 
    890 F.3d 60
    , 63 (2d
    Cir. 2018).
    9 
    Id.
     at 66–68.
    10 
    Id.
    11 
    Id.
     at 66–67.
    12 See 
    7 U.S.C. § 9
    (1), (3).
    8                                                           No. 20-1648-cv
    not “subject to the rules of any registered entity.” In December 2019,
    the magistrate judge issued a report and recommendation concluding
    that the motion for summary judgment should be granted. 13 On
    March 30, 2020, the district court adopted the recommendation in full
    and dismissed plaintiffs’ CEA claims. 14 On May 11, the district court
    entered final judgment on plaintiffs’ CEA claims pursuant to Rule
    54(b) 15 so that plaintiffs could file this appeal. 16
    DISCUSSION
    We review a decision granting summary judgment de novo, 17
    mindful that summary judgment is appropriate only “if the movant
    shows that there is no genuine dispute as to any material fact and the
    movant is entitled to judgment as a matter of law.” 18 “An issue of fact
    is genuine if the evidence is such that a reasonable jury could return
    a verdict for the nonmoving party. A fact is material if it might affect
    the outcome of the suit under the governing law.” 19 In evaluating a
    motion for summary judgment, we resolve all ambiguities and draw
    all permissible factual inferences in favor of the party against whom
    summary judgment is sought. 20
    13Myun-Uk Choi v. Tower Rsch. Cap. LLC (Choi IV), No. 14 Civ. 9912, 
    2019 WL 6871295
    , at *4–9 (S.D.N.Y. Dec. 17, 2019), report and recommendation
    adopted, No. 14 Civ. 9912, 
    2020 WL 1503446
     (S.D.N.Y. Mar. 30, 2020).
    14 Myun-Uk Choi v. Tower Rsch. Cap. LLC (Choi V), No. 14 Civ. 9912, 
    2020 WL 1503446
    , at *3–7 (S.D.N.Y. Mar. 30, 2020).
    15 See Fed. R. Civ. P. 54(b).
    16 Myun-Uk Choi v. Tower Rsch. Cap. LLC (Choi VI), No. 14 Civ. 9912, 
    2020 WL 2317363
    , at *1–2 (S.D.N.Y. May 11, 2020). The district court did not enter
    judgment on plaintiffs’ state-law claim for unjust enrichment. 
    Id.
     Only the
    CEA claims are at issue in this appeal.
    17 Fischer v. Forrest, 
    968 F.3d 216
    , 219 (2d Cir. 2020).
    18 Fed. R. Civ. P. 56(a).
    19 Frost v. N.Y.C. Police Dep't, 
    980 F.3d 231
    , 242 (2d Cir. 2020) (quoting
    SCR Joint Venture L.P. v. Warshawsky, 
    559 F.3d 133
    , 137 (2d Cir. 2009)).
    20 See Sloley v. VanBramer, 
    945 F.3d 30
    , 36 (2d Cir. 2019).
    9                                                                 No. 20-1648-cv
    Plaintiffs argue that the district court erred in granting
    summary judgment for four reasons. First, they contend that there is
    a genuine factual dispute as to whether Tower’s trading of KOPSI 200
    futures was subject to the rules of the CME, a registered entity under
    the CEA. Second, they contend that the district court abused its
    discretion by excluding the report of their expert, Professor Michael
    Greenberger. Third, they contend that the district court’s judgment
    contradicts our prior opinion denying Tower’s extraterritoriality
    defense, and therefore violates the law of the case. Fourth, they
    contend that the district court’s ruling will undermine public policy
    by placing trading of foreign futures in the United States beyond the
    reach of the CEA. We disagree with each of plaintiffs’ arguments, and
    therefore affirm.
    I.        The trading of KOSPI 200 futures on the KRX is not subject
    to the rules of the CME
    The CEA makes it unlawful to manipulate or attempt to
    manipulate the price of any futures contract “on or subject to the rules
    of any registered entity.” 21 Neither the KRX nor CME Globex is a
    registered entity under the CEA, 22 so plaintiffs concede that KOSPI
    200 futures are not traded “on” a registered entity—even when
    overnight orders are matched through CME Globex. The sole issue,
    therefore, is whether overnight trading of KOSPI 200 futures is
    nonetheless “subject to” a registered entity’s rules.
    Plaintiffs claim that overnight trading of KOSPI 200 futures is
    subject to the rules of the CME, a domestic exchange registered under
    the CEA. They contend that they identified sufficient evidence to
    survive summary judgment, and they argue that the district court
    erred by failing to draw all reasonable inferences in their favor.
    21 See 
    7 U.S.C. § 9
    (1), (3).
    22 The list of registered entities is defined by statute. See 7 U.S.C. § 1a(40).
    10                                                           No. 20-1648-cv
    Reviewing the record de novo, we disagree. As both the magistrate
    judge and district court explained, at least two sources of evidence
    conclusively demonstrate that trading of KOSPI 200 futures is not
    subject to the rules of the CME.
    First, the CME Rulebook 23—the source of the CME’s rules—
    specifies that it applies only to futures contracts that are created by
    and listed on the CME itself. It states that its rules apply to the trading
    and clearing of “Exchange futures,” 24 and it defines “Exchange”
    exclusively as the “Chicago Mercantile Exchange Inc.,” or the CME.25
    It is undisputed that KOSPI 200 futures are not CME futures; they are
    KRX futures created by and listed on the KRX. If there were any
    doubt, the CME Rulebook explicitly lists hundreds of CME futures
    contracts that are subject to its rules. 26 Nothing on that list mentions
    KOSPI 200 futures—let alone the KRX. Thus, the Rulebook itself is
    virtually conclusive evidence that the trading of KOSPI 200 futures is
    not “subject to” the rules of the CME.
    Second, both the CME and its parent, CME Group, have
    confirmed that the CME does not regulate the trading of KOSPI 200
    futures, even when trades are matched using CME Globex.                    In
    response to a subpoena early in this case, the CME and CME Group
    stated that the “CME does not regulate, review, or monitor the trading
    activity that occurs in the KOSPI Futures contract[s],” as “such
    23 The parties principally cite Chapter 5 of the Rulebook and its
    governing definitions. See J. App. at 1095–149 (Chapter 5); id. at 495–506
    (governing definitions). The full CME Rulebook is available online. See
    CME Rulebook, http://www.cmegroup.com/rulebook/CME.
    24 J. App. at 505 (emphasis added).
    25 Id. at 499.
    26 As reflected in the Table of Contents, the CME Rulebook devotes
    separate chapters to each futures contract. See id. at 245–51. Chapter 52, for
    example, lists “Class III Milk Futures” and specifies that such futures “shall
    be subject to the general rules and regulations of the Exchange.” Id. at 253.
    11                                                     No. 20-1648-cv
    activity is done by the Korea Exchange.” 27 CME Group later verified
    this in an unrebutted declaration. 28 The declaration explains that,
    while the CME and the KRX have a trade-matching services
    agreement under which KOSPI 200 futures are hosted on CME
    Globex for overnight trading, KOSPI 200 futures are “not listed on
    [the CME] and the trading itself remains governed by the KRX
    rulebook.” 29 The declaration explicitly states that the “KRX bears all
    responsibility and must perform all regulatory obligations with
    respect to any [KRX] contracts traded on CME Globex,” and it affirms
    that the “CME does not now, and has not ever, provided any of these
    regulatory functions” for such trading. 30 Thus, the CME itself has
    confirmed what its Rulebook already says: any trading of KOSPI 200
    futures is regulated by the KRX, not the CME.
    While plaintiffs acknowledge that KOSPI 200 futures are
    subject to the rules of the KRX, they dispute that KRX regulation is
    exclusive. They argue that Chapter 5 of the CME Rulebook, which
    concerns orders matched through CME Globex, speaks in broad
    terms and says nothing that would specifically exclude KOSPI 200
    futures from its scope. Setting aside the declaration and the CME
    Rulebook’s own restrictive statement on the scope of its rules,
    plaintiffs contend that the CME’s silence with respect to KOSPI 200
    futures creates “negative space” that, when combined with a
    smattering of other evidence, permits an inference that the CME in
    fact regulates overnight trading of KOSPI 200 futures alongside the
    KRX. This argument is without merit.
    Id. at 553.
    27
    28 See id. at 558–60 (declaration of Robert Sniegowski, CME Group
    Executive Director, Rules and Regulatory Outreach).
    29 Id. at 559 (emphasis added).
    30 Id. at 560 (emphasis added).
    12                                                         No. 20-1648-cv
    As a threshold matter, the CEA requires exchanges to
    “establish, monitor, and enforce” their rules affirmatively, including by
    setting forth “the terms and conditions of any contracts to be traded”
    on the exchange. 31 Pursuant to this requirement, the CME explicitly
    lists each futures contract that it regulates, and its sister exchanges
    have done the same: the CBOT rulebook lists CBOT futures; the
    NYMEX rulebook lists NYMEX futures; and the COMEX rulebook
    lists COMEX futures. None of the products listed in the rulebooks of
    these four exchanges overlaps, even though all four exchanges rely on
    the services of CME Globex for overnight order-matching.               This
    evidence strongly supports Tower’s argument that, absent an
    affirmative statement to the contrary, trading in a futures contract is
    confined to, and regulated by, the exchange that creates it. 32
    Moreover, linking KOSPI 200 futures to Chapter 5 of the CME
    Rulebook—which plaintiffs claim governs all trading through CME
    Globex—would yield absurd results. As plaintiffs concede, all of the
    CME’s sister exchanges have established analogous rules governing
    trading of their own futures contracts through CME Globex. Even the
    KRX has its own rules that apply when KRX futures are matched
    through the platform. 33      Plaintiffs’ theory would require us to
    conclude that any futures contract matched on CME Globex is
    regulated by every exchange with rules governing the use of the
    
    317 U.S.C. § 7
    (d)(2)(A)(ii).
    32See Psimenos v. E.F. Hutton & Co., 
    722 F.2d 1041
    , 1047 (2d Cir. 1983)
    (explaining that a futures contract “has no lawful existence or being
    independent of the designated contract market upon which it is traded”
    (citation omitted)).
    33 The KRX has confirmed that its own rulebook applies to overnight
    trading of KOSPI 200 futures, and an entire chapter in Part 3 of the KRX
    Rulebook specifically governs the trading of KRX futures contracts through
    CME Globex. See J. App. at 322–25 (“Chapter III: Special Case of Trade on
    CME Globex”).
    13                                                            No. 20-1648-cv
    platform. A CBOT trade would not only be subject to the rules of the
    CBOT, but also to the rules of the CME, the NYMEX, the COMEX, and
    perhaps even the KRX. 34 Unsurprisingly, CME Group itself says that
    is not how it works. As it explains in its declaration, each of the four
    exchanges offers “a different (and not overlapping) suite of products”
    and “[d]ifferent rulebooks govern trading depending on which
    [exchange] a product is listed on.” 35
    Even if plaintiffs could present a coherent theory, the fragments
    of evidence they cite would not support a reasonable inference that
    overnight trades of KOSPI 200 futures are subject to the rules of the
    CME. Although plaintiffs place great stock in a handful of rules in
    Chapter 5 of the CME Rulebook, none of those rules contains any
    affirmative indication that the CME intended them to apply to the
    trading of KOSPI 200 futures on the KRX. 36 To the contrary, the rules
    cross-reference the same definitions that restrict their scope to CME
    futures traded on CME Group markets.                Plaintiffs’ reliance on
    comments in the CME Globex Reference Guide 37 fares no better. The
    CME Globex is not a registered entity, so the Guide does not reflect a
    registered entity’s rules.      Indeed, the Guide specifically instructs
    readers to “refer to the CME, CBOT or NYMEX Rulebooks” for “the
    text of actual rules or interpretations.” 38
    Plaintiffs also attempt to peg KOSPI 200 futures to the CME’s
    rules through several other documents, none of which supports their
    As plaintiffs concede in their reply brief, they could just as well argue
    34
    that KOSPI 200 futures are subject to the rules of the CBOT, the NYMEX, or
    the COMEX. See Appellants’ Reply Br. at 8 n.6.
    35 J. App. at 559.
    36 See 
    id. at 1136
     (Rule 574); 
    id.
     at 1137–39 (Rule 578); 
    id. at 1139
     (Rule
    579); 
    id. at 1140
     (Rule 580); 
    id.
     (Rule 583.A); 
    id. at 1143
     (Rule 588.H).
    37 See 
    id.
     at 1833–61.
    38 Id. at 1854.
    14                                                         No. 20-1648-cv
    case. They first point to two documents—a 1989 memorandum 39 and
    a 2008 “no action” letter 40—published by the Commodity Futures
    Trading Commission (CFTC). But, as the district court explained,
    neither of those documents purports to address a foreign exchange’s
    use of CME Globex for overnight order-matching—particularly
    where, as here, the futures are offered and sold exclusively on a
    foreign exchange. 41 Plaintiffs next point to a 2012 email 42 from CME
    Group warning that Tower was “consuming KRX market data
    without the appropriate licensing” and that CME Group would
    “continue to monitor for non-compliance.” 43 But CME Group is not a
    registered entity under Section 9 and, even if it were, the district court
    correctly observed that the email concerns CME Group’s capacity as
    a vendor for KRX market data—not as a regulator of KRX futures
    trading. 44
    Unable to identify any affirmative evidence that the CME’s
    rules apply, plaintiffs turn the tables and argue that Tower has failed
    to prove the negative. They cite a handful of cases in which courts
    have applied the CEA to trades that were matched through CME
    Globex. But when confronted with the fact that all of those cases
    39See id. at 922–1079.
    40See id. at 488–94.
    41 Choi V, 
    2020 WL 1503446
    , at *5. The 1989 memorandum considered
    rules that “relate solely to CME contracts” and expressly noted that
    “[i]ssues relating to foreign exchanges are not currently before the
    Commission.” J. App. at 929, 1075. The 2008 “no action” letter says nothing
    about the trading of KOSPI 200 futures on the KRX. Rather, it confirms that
    U.S. brokers—who are not at issue in this case—may “offer [or] s[ell]” KOSPI
    200 futures to their U.S. customers provided that the brokers remain
    governed by certain CFTC regulations. Id. at 494.
    42 See J. App. at 2034–35.
    43 Id. at 2034–35.
    44 See Choi V, 
    2020 WL 1503446
    , at *6.
    15                                                         No. 20-1648-cv
    involved products traded on the CME or another registered entity, 45
    plaintiffs pivot, arguing that “no court has ever held” that a futures
    contract matched through CME Globex “is not covered by the CEA.” 46
    Plaintiffs take the same tack with the CME Group declaration.
    Although they acknowledge that the declaration “says that the KRX
    Rulebook applies exclusively to KOSPI 200 futures trading,” they
    assert that “it conspicuously fails to say that the CME Rulebook does
    not apply to KOSPI 200 futures trading on the CME Globex.” 47 In both
    cases, the negative inferences that plaintiffs ask us to draw are nearly
    fantastical. They fail to create a genuine issue for trial.
    II.        The district court did not abuse its discretion by excluding
    Professor Greenberger’s expert report
    In addition to relying on the evidence discussed above,
    plaintiffs argue that the district court erred by declining to consider
    as evidence the written report of their expert witness, Professor
    Greenberger, who opined that Tower’s trading of KOSPI 200 futures
    was “subject to” the rules of the CME. 48 The district court made no
    such error.
    See CFTC v. Oystacher, No. 15 Civ. 9196, 
    2016 WL 3693429
    , at *3-4, *8
    45
    (N.D. Ill. July 12, 2016) (COMEX, NYMEX, CME, and Chicago Board Option
    Exchange Futures Exchange futures contracts); Laydon v. Mizuho Bank, Ltd.,
    No. 12 Civ. 3419, 
    2014 WL 1280464
    , at *2 (S.D.N.Y. Mar. 28, 2014) (CME
    futures contracts); CFTC v. Taylor, No. 12 Civ. 8170, 
    2013 WL 5437362
    , at *2
    (S.D.N.Y. Aug. 29, 2013) (CME futures contracts); In re Rough Rice
    Commodity Litig., No. 11 Civ. 618, 
    2012 WL 473091
    , at *1 (N.D. Ill. Feb. 9,
    2012) (CBOT futures contracts); CFTC v. Garofalo, No. 10 Civ. 2417, 
    2010 WL 11245430
    , at *1 (N.D. Ill. Dec. 21, 2010) (CME futures contracts).
    46 Appellants’ Br. at 44 (emphasis added).
    47 Id. at 33.
    48 J. App. at 666; see generally id. at 660–72.
    16                                                           No. 20-1648-cv
    It is well established that expert testimony admitted under Rule
    702 must be relevant, 49 meaning it must “help the trier of fact to
    understand the evidence or to determine a fact in issue.” 50 Expert
    testimony that usurps the role of the factfinder or that serves
    principally to advance legal arguments should be excluded. 51 The
    proponent of expert testimony carries the burden of establishing its
    admissibility by a preponderance of the evidence, 52 and we review a
    trial judge’s exclusion of expert testimony for abuse of discretion. 53
    Here, Professor Greenberger’s report functions as little more
    than a legal brief that parrots plaintiffs’ arguments.           The report
    identifies a handful of rules in Chapter 5 of the CME Rulebook (the
    same rules that plaintiffs marshal in their briefing), and it cites several
    cases and CFTC documents that Professor Greenberger claims
    supports his interpretation of those rules (the same cases and CFTC
    documents that plaintiffs cite). Much of Professor Greenberger’s
    report advances policy arguments. As the district court explained,
    the report “offers scant input” on the issues appealed and, in any
    event, would not alter the outcome on summary judgment. 54 The
    district court did not abuse its discretion by excluding it.
    III.      The district court’s judgment does not contradict our prior
    ruling in this case
    Despite their failure to show that KOSPI 200 futures are subject
    to the rules of the CME, plaintiffs argue that we should reverse the
    district court because its judgment contradicts our prior decision,
    49See Daubert v. Merrell Dow Pharm., Inc., 
    509 U.S. 579
    , 597 (1993).
    50Fed. R. Evid. 702.
    51 See United States v. Lumpkin, 
    192 F.3d 280
    , 289 (2d Cir. 1999); Hygh v.
    Jacobs, 
    961 F.2d 359
    , 364 (2d Cir. 1992).
    52 United States v. Williams, 
    506 F.3d 151
    , 160 (2d Cir. 2007).
    53 Gen. Elec. Co. v. Joiner, 
    522 U.S. 136
    , 142–43 (1997).
    54 Choi V, 
    2020 WL 1503446
    , at *7.
    17                                                             No. 20-1648-cv
    which is now law of the case. As explained above, our prior opinion
    found it plausible that parties trading KOSPI 200 futures on the
    overnight market of the KRX incurred irrevocable liability in the
    United States, where the orders were matched through CME Globex.
    Although        the    opinion     focused      exclusively     on     Tower’s
    extraterritoriality defense under Morrison, plaintiffs contend that the
    district court’s entry of summary judgment “effectively overrules”
    that decision by holding that the CEA does not, in fact, cover the
    trading at issue. 55
    The law of the case doctrine “forecloses reconsideration of
    issues that were decided—or that could have been decided—during
    prior proceedings.” 56 It applies “both to that which is expressly
    decided as well as to everything decided by necessary implication.” 57
    While the doctrine “does not rigidly bind [us] to [our] former
    decisions,” 58 we generally adhere to prior decisions in subsequent
    stages of the same case “unless ‘cogent and compelling reasons
    militate otherwise.’” 59 Cogent and compelling reasons justifying a
    departure from the law of the case may include “an intervening
    change in law, availability of new evidence, or ‘the need to correct a
    clear error or prevent manifest injustice.’” 60
    The district court’s judgment does not violate the law of the
    case. As we noted above, our prior opinion addressed only whether
    55Appellants’ Br. at 19.
    56Doe v. E. Lyme Bd. of Educ., 
    962 F.3d 649
    , 662 (2d Cir. 2020) (quoting
    United States v. Williams, 
    475 F.3d 468
    , 471 (2d Cir. 2007)).
    57 United States v. Yonkers Bd. of Educ., 
    856 F.2d 7
    , 11 (2d Cir. 1988)
    (internal quotation marks, citation, and alteration omitted).
    58 Johnson v. Holder, 
    564 F.3d 95
    , 99 (2d Cir. 2009) (quoting Higgins v. Cal.
    Prune & Apricot Grower, Inc., 
    3 F.2d 896
    , 898 (2d Cir. 1924)).
    59 
    Id.
     (quoting United States v. Quintieri, 
    306 F.3d 1217
    , 1225 (2d Cir.
    2002)).
    60 
    Id.
     at 99–100 (quoting Quintieri, 
    306 F.3d at 1230
    ).
    18                                                             No. 20-1648-cv
    application of the CEA to Tower’s alleged conduct would constitute
    an extraterritorial application of the Act in violation of Morrison. 61 In
    concluding that it would not, our analysis focused exclusively on
    Morrison’s “domestic transactions” test and declined to address
    whether the CEA might plausibly have territorial reach over
    plaintiffs’ allegations on the basis that CME Globex is a “domestic
    exchange.” 62 In any event, our conclusion that Morrison does not
    prevent the CEA from regulating these transactions says nothing
    about whether a registered entity affirmatively subjected Tower’s
    trading to its rules.        Our prior opinion did not address the
    requirement in Section 9 that trading be “subject to the rules of [a]
    registered entity,” and it did not resolve whether the trading of KOSPI
    200 futures through CME Globex was in fact governed by the CME
    Rulebook.
    IV.       The district court properly rejected plaintiffs’ public policy
    arguments
    Ultimately, plaintiffs fall back on public policy. They remind
    us that the CEA was designed as a remedial statute, and that it serves
    an important role in protecting retail investors and promoting the
    integrity of futures markets. 63 They argue that, if the district court’s
    decision stands, it will create a “gigantic loophole” in which plausibly
    domestic transactions evade enforcement under the CEA simply
    61Choi III, 890 F.3d at 66.
    62Id. at 66–67.
    63 See Loginovskaya, 764 F.3d at 270 (explaining that “[t]he CEA . . . serves
    the crucial purpose of protecting the innocent individual investor—who
    may know little about the intricacies and complexities of the commodities
    market—from being misled or deceived” (internal quotation marks and
    citation omitted)).
    19                                                              No. 20-1648-cv
    because they are not “subject to the rules of [a] registered entity.” 64
    Plaintiffs’ arguments are unpersuasive.
    First, as the district court recognized, it is the CEA itself that
    restricts its scope to futures contracts “on or subject to the rules of [a]
    registered entity.” 65 Our task is to “give the statute the effect its
    language suggests, . . . not to extend it to admirable purposes it might
    be used to achieve.” 66        Thus, while it might further certain of
    plaintiffs’ policy interests for Congress to have legislated more
    expansively, it did not do so, and it is not our place to effectively strike
    Section 9’s requirement from the text of the law. 67
    Second, plaintiffs’ policy arguments are overstated in any
    event. As plaintiffs concede, the trading of KOSPI 200 futures on the
    KRX will remain subject to the rules of the KRX, including when they
    are matched using CME Globex. The KRX prohibits manipulative
    trading, and it enforces its rules through a Market Oversight
    Commission that “conducts market surveillance . . . to prevent unfair
    trading practices such as manipulation.” 68 Indeed, plaintiffs initiated
    this case only after South Korean regulatory authorities identified
    irregularities in Tower’s trading and referred Tower to South Korean
    prosecutors. Plaintiffs do not suggest that the absence of concurrent
    U.S. regulation leaves them unprotected from the wrongdoing of
    would-be manipulators.
    64See Appellants’ Br. at 51–54; see also 
    7 U.S.C. § 9
    (1), (3).
    65See 
    7 U.S.C. § 9
    (1), (3).
    66 Morrison, 
    561 U.S. at 270
    .
    67 See Prime Int’l Trading, Ltd. v. BP P.L.C., 
    937 F.3d 94
    , 108 (2d Cir. 2019)
    (“‘[T]he sole function of the courts is to enforce [the CEA] according to its
    terms,’ not to reinvent it.” (second alteration in original) (quoting Arlington
    Cent. Sch. Dist. Bd. of Educ. v. Murphy, 
    548 U.S. 291
    , 296 (2006))).
    68 See J. App at 488.
    20                                                       No. 20-1648-cv
    Finally, while it appears that the trading of foreign futures on a
    foreign exchange will rarely be subject to the rules of a registered
    entity, our decision today is a principally a factual one. Nothing in
    our opinion is intended to interfere with existing authorities under
    the CEA or other federal statutes that may allow domestic exchanges
    to regulate foreign futures, in particular when such futures are offered
    and sold in the United States.
    CONCLUSION
    For the foregoing reasons, we AFFIRM the judgment of the
    district court.