MISO Transmission Owners v. FERC ( 2022 )


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  •  United States Court of Appeals
    FOR THE DISTRICT OF COLUMBIA CIRCUIT
    Argued November 18, 2021              Decided August 9, 2022
    No. 16-1325
    MISO TRANSMISSION OWNERS, ET AL.,
    PETITIONERS
    v.
    FEDERAL ENERGY REGULATORY COMMISSION,
    RESPONDENT
    MIDCONTINENT INDEPENDENT SYSTEM OPERATOR, INC., ET
    AL.,
    INTERVENORS
    Consolidated with 16-1326, 20-1182, 20-1240, 20-1241,
    20-1248, 20-1251, 20-1267, 20-1513
    On Petitions for Review of Orders of the
    Federal Energy Regulatory Commission
    Christopher R. Jones and Matthew J. Binette argued the
    causes for petitioner MISO Transmission Owners, et al. With
    them on the joint briefs were Miles H. Kiger, Wendy N. Reed,
    Michael J. Thompson, Victoria M. Lauterbach, Ryan J. Collins,
    2
    Steven J. Ross, and Stacey L. Burbure. David S. Berman
    entered an appearance.
    David E. Pomper argued the cause for petitioners on
    Return Issues. With him on the briefs were Robert A.
    Weishaar, Jr., Omar Bustami, Vasiliki Karandrikas, Gerit F.
    Hull, Matthew R. Rudolphi, Michael Postar, Bhaveeta K.
    Mody, Sean T. Beeny, Barry Cohen, Andrea I. Sarmentero
    Garzon, John Michael Adragna, James H. Holt, David Eugene
    Crawford, and Benjamin Sloan.
    Eric B. Wolff argued the cause for petitioners on Refund
    Issues. With him on the briefs were Jane E. Rueger, Robert A.
    Weishaar, Jr., Alison R. Caditz, Vasiliki Karandrikas, Omar
    Bustami, Matthew R. Rudolphi, David E. Pomper, Gerit F.
    Hull, Sean T. Beeny, Barry Cohen, Andrea I. Sarmentero
    Garzon, Michael Postar, Bhaveeta K. Mody, James H. Holt,
    David Eugene Crawford, John Michael Adragna, and
    Benjamin Sloan. James K. Mitchell entered an appearance.
    Jason T. Gray, Michael R. Fontham, Dana M. Shelton, and
    Justin A. Swaim were on the briefs for intervenors supporting
    Consumer-Side petitioners. Arthur W. Iler entered an
    appearance.
    Catherine P. McCarthy, Blake R. Urban, Nicholas J.
    Cicale, Gary Epler, Phyllis E. Lemell, Lisa B. Luftig, Mary E.
    Grover, Sean A. Atkins, David M. Gossett, S. Mark Sciarrotta,
    Jeffrey M. Jakubiak, and Jennifer C. Mansh were on the brief
    for amici curiae in support of Transmission Owning
    petitioners.
    Lona T. Perry, Deputy Solicitor, Federal Energy
    Regulatory Commission, argued the cause for respondent.
    3
    With her on the brief were Matthew R. Christiansen, General
    Counsel, and Robert H. Solomon, Solicitor.
    Michael R. Fontham argued the cause for intervenors in
    support of respondent aligned with remaining petitioners. With
    him on the brief were Andrea I. Sarmentero Garzon, Matthew
    R. Rudolphi, Sean T. Beeny, Barry Cohen, Benjamin Sloan,
    Joshua E. Adrian, Gerit F. Hull, James H. Holt, David Eugene
    Crawford, Robert A. Weishaar, Jr., David E. Pomper, Vasiliki
    Karandrikas, Omar Bustami, Michael Postar, Bhaveeta K.
    Mody, Dana M. Shelton, Justin A. Swaim, Deborah A. Moss,
    Jason T. Gray, and Emerson J. Hilton. Arthur W. Iler entered
    an appearance.
    Matthew J. Binette argued the cause for intervenors in
    support of respondent. With him on the joint brief were Steven
    J. Ross, Stacey L. Burbure, Wendy N. Reed, Michael J.
    Thompson, Victoria M. Lauterbach, Ryan J. Collins,
    Christopher R. Jones, and Miles H. Kiger. David S. Berman
    entered an appearance.
    Before: SRINIVASAN, Chief Judge, KATSAS and WALKER,
    Circuit Judges.
    Opinion for the Court filed by Circuit Judge WALKER.
    WALKER, Circuit Judge: The Federal Energy Regulatory
    Commission is responsible for ensuring that interstate
    electricity rates are “just and reasonable.” 16 U.S.C.
    §§ 824d(a), 824e(a). To do so, it approves electricity
    providers’ proposed rate changes, and it can require them to
    change their rates if the rates become unreasonable. This case
    is about one of FERC’s rate determinations.
    4
    Midcontinent Independent System Operator, Inc.
    administers the electric grid on behalf of the companies that
    own transmission lines. Those transmission owners invested
    money to build their transmission lines, and MISO must charge
    customers electricity-transmission rates that provide those
    companies an appropriate return on their investment. That
    return-on-equity component of the transmission rates, which
    we’ll just call the Return, is at issue in this case.
    In this case, a group of customers thought MISO provided
    transmission owners a too-generous Return. They asked FERC
    to reduce that aspect of MISO’s rates. FERC did. In the
    process, it completely overhauled its approach to setting an
    appropriate Return.
    Both the customers and transmission owners now
    challenge several aspects of the FERC proceedings as unlawful
    or arbitrary and capricious.
    We agree with the customers that FERC’s development of
    the new Return methodology was arbitrary and capricious, so
    we vacate its rate-determination orders and remand for further
    proceedings. Because the other challenged aspects of FERC’s
    orders flow from FERC’s rate determination, we do not reach
    them.
    I
    We start this section with some background on the general
    regulatory framework for electricity-transmission rates. Then
    we describe the history of FERC’s approach to Return
    determinations. Finally, we explain what happened in these
    proceedings.
    5
    A
    For most of the twentieth century, vertically integrated
    state and local utilities monopolized electricity markets. See
    Atlantic City Electric Co. v. FERC, 
    295 F.3d 1
    , 4 (D.C. Cir.
    2002). When technological progress enabled competitors to
    offer lower prices for electricity, the incumbent utilities used
    their control of transmission lines to keep competitors out of
    the market. 
    Id.
     That exclusion caused higher prices. So in
    1996, FERC required utilities to provide open access to
    transmission lines. 
    Id.
     To help achieve its open-access goals,
    FERC created a framework for independent companies, called
    independent system operators, that would impartially operate
    transmission lines. 
    Id. at 5
    .
    MISO performs that service for fifteen states in the middle
    of the country from Louisiana up to Minnesota (and beyond to
    Manitoba). In exchange for its services, it charges transmission
    rates that approximate the costs it incurs plus an appropriate
    return on equity for the transmission owners’ original
    investment in building the lines. See FERC, Energy Primer: A
    Handbook of Energy Market Basics 59-60 (2020).
    Like all public utilities, MISO must file its proposed rates
    with FERC for approval. As part of its review, FERC ensures
    that the Return portion of the rates is appropriate to compensate
    transmission owners for the risks they took and to attract future
    investment in transmission lines. Emera Maine v. FERC, 
    854 F.3d 9
    , 20 (D.C. Cir. 2017).
    There are two ways that MISO’s rates can change.
    One, called a Section 205 proceeding, is utility-initiated.
    If MISO wishes to change its rates, it can file a new set of
    proposed rates with FERC. 16 U.S.C. § 824d(d). FERC then
    6
    reviews the proposed rates to determine whether they are just
    and reasonable. Id. § 824d(e). If they are, MISO can charge
    them. NRG Power Marketing, LLC v. FERC, 
    862 F.3d 108
    ,
    114 (D.C. Cir. 2017). If not, FERC rejects them. 
    Id.
    The other, called a Section 206 proceeding, is customer-
    or FERC-initiated. A customer can file a complaint alleging
    that a current rate is unjust and unreasonable, or FERC can set
    a hearing on its own motion. 16 U.S.C. § 824e(a). At step one,
    FERC decides if the old rate is unjust and unreasonable. Id. If
    so, then FERC proceeds to step two and sets a new rate. Id.
    Until FERC sets a new rate in a Section 206 proceeding,
    customers continue to pay the challenged rates. See City of
    Anaheim v. FERC, 
    558 F.3d 521
    , 525 (D.C. Cir. 2009). So
    Congress gave FERC limited refund authority. At the
    beginning of the proceeding, FERC sets “a refund effective
    date.” 16 U.S.C. § 824e(b). It can then give refunds of any
    excess payments for fifteen months after that refund effective
    date. Id. Those excess payments are calculated as the
    difference between the old, challenged rate and the new rate
    ordered by FERC. Id.
    This case is about a Section 206 proceeding.
    B
    To understand what FERC did in this proceeding, it helps
    to have some historical background on FERC’s methodology
    for assessing the reasonableness of the existing Return and, if
    necessary, setting a new one.
    Since the 1980s, FERC calculated the Return with the aid
    of a financial tool called the discounted-cash-flow model. That
    model uses a company’s stock price to represent the company’s
    7
    value to investors. Canadian Association of Petroleum
    Producers v. FERC, 
    254 F.3d 289
    , 293 (D.C. Cir. 2001). It
    assumes that the stock price is equal to all the dividends the
    company will pay out in the future “discounted at a market rate
    commensurate with the stock’s risk.” 
    Id.
     A simplified version
    of that baseline formula is P = D/(r-g), “where P is the price of
    the stock at the relevant time, D is the dividend to be paid at
    the end of the first year, r is the rate of return and g is the
    expected growth rate of the firm.” 
    Id.
     That is the version
    investors use to try to calculate a company’s stock price. But
    to calculate an appropriate Return for transmission owners,
    FERC rearranges the equation to be:
    r = D/P + g.1
    For publicly traded companies, calculating an appropriate
    Return with the discounted-cash-flow model is relatively easy
    because of its publicly traded stock price. But for privately
    held companies like the transmission owners, which have no
    public stock price, FERC uses a proxy group of comparable,
    publicly traded companies. Id. at 293-94. With that proxy
    group of public companies, FERC can approximate what a
    discounted-cash-flow analysis should look like for the
    privately held companies at issue. Id.
    When FERC chooses a proxy group and conducts a
    discounted-cash-flow analysis for each company in the group,
    it gets a range of possible Returns that FERC calls the “zone of
    reasonableness.” Emera Maine v. FERC, 
    854 F.3d 9
    , 15 (D.C.
    1
    As we said, r = D/P + g is a simplified version of FERC’s formula.
    The actual, more complicated formula includes a dividend multiplier,
    which accounts “for the fact that dividends are paid on a quarterly
    basis.” JA 514. It is r = D/P(1 + .5g) + g. But because the dividend
    multiplier affects none of the analysis in this case, we’ll use the
    simplified formula when discussing the discounted-cash-flow model.
    8
    Cir. 2017). A Return must be a single value, so FERC then
    needs to choose a point within the zone. It typically uses the
    midpoint, at least for independent system operators like MISO.
    See Southern California Edison Co. v. FERC, 
    717 F.3d 177
    ,
    186 (D.C. Cir. 2013).
    That was the state of play until 2014: FERC would
    produce a zone of reasonableness using a discounted-cash-flow
    analysis of proxy group companies, then set the Return at the
    midpoint.
    Then FERC changed things up. In a rate-review
    proceeding for New England’s independent system operator,
    FERC found that anomalous market conditions required a
    higher Return than the one provided by the midpoint of the
    discounted-cash-flow model’s zone of reasonableness. Emera
    Maine, 854 F.3d at 18. It looked at several other models to
    determine how much higher the Return should go and
    ultimately set the Return at the midpoint of the upper half of
    the zone of reasonableness. Id.
    That brings us to this case.
    C
    This case started with two separate Section 206 complaints
    against MISO’s rates.
    In 2013, a group of customers believed the Return
    component of MISO’s existing rate was too high. They filed a
    Section 206 complaint asking FERC to lower it. That was this
    case’s first complaint.
    FERC set a refund effective date of November 12, 2013,
    which meant that customers could only get refunds for
    9
    overpayments through February 11, 2015. But FERC did not
    resolve the first complaint by February 11, 2015. The following
    day, a different group of customers filed a complaint
    challenging the same MISO rate. That was this case’s second
    complaint.
    Finally, on September 28, 2016, FERC resolved the first
    complaint in Opinion No. 551. It agreed with the customers
    and reduced the Return from 12.38% to 10.32%. In doing so,
    it used the same Return-setting methodology that it had
    developed in the New England proceeding.
    The next year, in Emera Maine v. FERC, we vacated
    FERC’s orders from the New England proceeding. 854 F.3d at
    30. We identified two infirmities in FERC’s analysis. First, as
    the transmission owners had argued, FERC “never actually
    explained how” the New England transmission owners’
    existing Return “was unjust and unreasonable.” Id. at 26. And
    second, as the customers had argued, FERC failed to justify its
    decision to set the Return at the three-quarters point of the zone
    of reasonableness. Id. at 28-29.
    Because FERC had relied so heavily in this proceeding on
    the orders that we vacated in Emera Maine, FERC chose to
    revisit Opinion 551. It set the first complaint for rehearing and
    informed the parties that it planned to resolve the second
    complaint in the same rehearing proceeding.
    In its rehearing order, FERC proposed an entirely new
    methodology for calculating a just and reasonable Return. The
    proposal used four different financial models, giving each
    equal weight:
    •   Model 1, discounted cash flow (as described three
    pages ago);
    10
    •   Model 2, capital-asset pricing;2
    •   Model 3, expected earnings;3 and
    •   Model 4, risk premium.4
    FERC planned to use the first three models, each of which
    produce a zone of reasonableness, to answer the threshold
    question whether an existing rate is unjust and unreasonable.
    Because risk premium (Model 4) produces only a single point,
    FERC intended to leave it out of that first step. It planned to
    create a composite zone produced by the average of the first
    three models’ zones of reasonableness, then divide the
    composite zone to create presumptively just and reasonable
    ranges for utilities based on their risk profiles, as this image
    shows:
    2
    The Return for this model depends on, among other things, a risk-
    free rate like the Treasury-bond rate, an analysis of the returns in the
    market, and an estimate of the company’s riskiness. Part III.B of this
    opinion explains it in more detail.
    3
    This model produces a Return based on the earnings investors in
    comparable stocks expect to receive based on those stocks’ “book
    value,” which measures the difference between a company’s assets
    and liabilities. Spoiler alert: FERC will later drop this model from
    its methodology.
    4
    This model subtracts past corporate-utility-bond rates from past
    Returns to calculate an average risk premium that FERC has given
    in the past. The new Return is that number added to the current
    Treasury-bond rate. We will explain more about this model in Part
    III.E.
    11
    Then, if FERC found an existing Return unjust and
    unreasonable, it would set a new Return by averaging the
    midpoint (or the one-quarter or three-quarters point for utilities
    of below-average and above-average risk respectively) of the
    first three models with the single point that the risk-premium
    model (Model 4) produces.
    A year later, when FERC issued its second order in this
    proceeding — Opinion No. 569 — it abandoned expected
    earnings (Model 3) and risk premium (Model 4), and made
    other, more minor tweaks to its proposed Return methodology.
    It then applied the new methodology, again found the pre-
    complaint 12.38% Return unjust and unreasonable, and set a
    new Return of 9.88%. FERC backdated that new Return to
    make it effective as of September 28, 2016, requiring the
    transmission owners to refund — for the period between the
    first and second orders — the difference between the 10.32%
    12
    FERC had set in its first order and the 9.88% it had set in its
    second order.5
    As it had promised, FERC also resolved the second
    complaint in Opinion 569. It determined that the currently
    effective Return was the new 9.88% Return that it had just
    imposed. Then it found that 9.88% was not unjust and
    unreasonable. It therefore did not order a new rate in response
    to the second complaint. And because it had not ordered a new
    rate, FERC concluded that it could not order a refund for the
    second complaint’s fifteen-month refund period.
    The customers and transmission owners alike found fault
    with Opinion 569, so both petitioned for rehearing on several
    grounds. FERC granted rehearing and, in its third order
    — Opinion 569-A — FERC again changed its Return
    methodology. It added risk-premium (Model 4) back into the
    mix and shifted the presumptively just and reasonable zones,
    among other things.
    After explaining its changes, FERC applied the new
    Return methodology to, yet again, find the pre-complaint
    12.38% Return unjust and unreasonable. FERC then set a new
    Return of 10.02%, which it again backdated to September 28,
    2016. Finally, it used that 10.02% Return to again reject the
    second complaint.
    The parties again sought rehearing before FERC. In
    response, FERC issued Opinion No. 569-B, which tweaked the
    Return methodology a bit without making any further major
    changes.
    5
    The MISO transmission owners’ primary challenge focuses on the
    lawfulness of this backdating decision. Because we do not reach that
    question, we won’t delve into the sides’ conflicting positions.
    13
    This chart summarizes the relevant FERC proceedings.
    First Section 206 Complaint: November 12, 2013
    (Refund period = November 12, 2013 – February 11, 2015)
    Second Section 206 Complaint: February 12, 2015
    (Refund period = February 12, 2015 – May 11, 2016)
    September 28, 2016                New Return = 10.32%
    FERC Opinion No. 551              Orders refunds for November
    12, 2013 – February 11, 2015
    Only addresses first complaint    Return methodology: applies
    methodology from the New
    England ISO proceeding
    April 14, 2017: This Court issues Emera Maine, vacating the
    opinion on which Opinion 551 was based.
    November 21, 2019                 New Return = 9.88%
    FERC Opinion No. 569              Orders refunds for November
    12, 2013 – February 11, 2015
    and backdates the new rate’s
    effective date to September 28,
    2016, when it issued Opinion
    551.
    Addresses both complaints         Dismisses second complaint.
    14
    Return methodology: rejects the
    expected-earnings and risk-
    premium models; will use only
    the discounted-cash-flow and
    capital-asset models.
    May 21, 2020                 New Return = 10.02%
    FERC Opinion No. 569-A       Requires refunds for the same
    periods as Opinion 569.
    Addresses both complaints    Still    dismisses       second
    complaint.
    Return methodology: will now
    use the risk-premium model in
    the Return analysis in addition
    to the discounted-cash-flow and
    capital-asset models.
    November 19, 2020            Return still = 10.02%
    FERC Opinion No. 569-B       Requires refunds for the same
    periods as Opinion 569-A
    Addresses both complaints    Still    dismisses       second
    complaint.
    Return methodology: corrected
    certain inputs to the risk-
    premium model but continued to
    reach the same result it reached
    in Opinion No. 569-A
    15
    II
    Under the Administrative Procedure Act’s arbitrary-and-
    capricious standard, our review of FERC’s ratemaking choices
    is limited. 
    5 U.S.C. § 706
    (2)(A); see also Emera Maine v.
    FERC, 
    854 F.3d 9
    , 21-22 (D.C. Cir. 2017). We must deny the
    petitions for review as long as FERC “has made a principled
    and reasoned decision supported by the evidentiary record.”
    
    Id. at 22
     (quoting Southern California Edison Co. v. FERC, 
    717 F.3d 177
    , 181 (D.C. Cir. 2013)). That inquiry includes
    verifying that FERC had a reasoned basis for any changes of
    heart. Verso Corp. v. FERC, 
    898 F.3d 1
    , 7 (D.C. Cir. 2018).
    III
    The customers challenge FERC’s new Return
    methodology on five grounds. First, they argue that FERC
    should not have altered its previous approach to balancing
    long-term and short-term growth rates in the discounted-cash-
    flow model (Model 1). Second, they challenge three aspects of
    FERC’s approach to the capital-asset model (Model 2). Third,
    they argue that FERC’s creation of presumptively just and
    reasonable ranges at step one of the Section 206 analysis was
    arbitrary and capricious. Fourth, they argue that FERC should
    have set the new Return based on the median of the zone of
    reasonableness rather than the midpoint. And fifth, they
    challenge FERC’s decision to resuscitate the risk-premium
    model (Model 4) in its second rehearing order shortly after
    interring the model in its first rehearing order.
    We find the first four of those arguments unpersuasive.
    But we agree with the customers’ final argument. And that
    conclusion is alone enough to make FERC’s rate orders
    arbitrary and capricious.
    16
    A
    The customers take aim at a change that FERC made to its
    discounted-cash-flow analysis (Model 1). Remember, the
    simplified version of that is r = D/P + g, with the letters
    representing the Return, dividend, stock price, and expected
    growth rate.
    In conducting a discounted-cash-flow analysis for a
    company, FERC balances short-term and long-term expected
    growth to pick an expected growth rate. Before 1999, FERC
    used a fifty-fifty split. Canadian Association of Petroleum
    Producers v. FERC, 
    254 F.3d 289
    , 292, 297 (D.C. Cir. 2001).
    After 1999, FERC used a two-thirds-short-term versus one-
    third-long-term split. Id. at 297.
    In this proceeding, FERC changed to a four-fifths-short-
    term versus one-fifth-long-term split. When we approved the
    1999 change (from the pre-1999 fifty-fifty split), we noted that
    because this kind of weighting doesn’t lend itself to “strict
    rules, it would likely be difficult to show that [FERC] abused
    its discretion in the weighting choice.” Id.
    That remains true. Short-term rates are more reliable
    projections; long-term rates just “normalize any distortions” in
    the short-term rates. Id. (cleaned up). Recently, the
    normalizing value of long-term rates has declined as the short-
    term and long-term projections have converged. So as the
    importance of long-term rates has declined, FERC decided that
    their role in the discounted-cash-flow analysis should too. That
    was not arbitrary and capricious.
    17
    B
    The customers next challenge three aspects of FERC’s
    application of the capital-asset model (Model 2). We reject
    each challenge.
    That model begins with the following formula:
    Return = risk-free rate + beta(expected return – risk-free rate).
    Let’s break down each term in that formula, as FERC
    applied it in this proceeding:
    •   The risk-free rate is the Treasury-bond rate.
    •   The “beta” is a company-specific value that industry
    experts assign to measure a company’s riskiness as an
    investment. A beta value of one represents average
    risk, such that a beta below one represents a lower-risk
    company and a beta above one represents a higher-risk
    company.6
    6
    Specifically, the beta looks at risk as compared to the full market.
    So an investment that “fluctuates exactly in step with the market,”
    which means that the investment’s “rate of return increases on
    average by 1 percent when the market’s return increases 1 percent,”
    will have a beta of one. A. Lawrence Kolbe, James Read, Jr. &
    George Hall, The Cost of Capital: Estimating the Rate of Return for
    Public Utilities 70 (1984).
    18
    •   The expected return is the result of a discounted-cash-
    flow analysis of all dividend-paying companies in the
    S&P 500.7
    Although FERC’s application of the model begins with
    that formula, it doesn’t end with it. Before running the formula,
    FERC adjusts the beta towards 1.0 because some finance
    scholars believe that betas “converge to 1.0” in the long run.
    JA 611 (quotation marks omitted). Then, after running the
    formula, FERC takes the formula’s Return result and applies a
    “size-premium adjustment” to that result. The adjustment is a
    value meant to ensure that the model adequately accounts for
    companies’ sizes.
    For this model, the customers challenge: (1) FERC’s
    decision not to include long-term growth rates in its analysis of
    7
    For some concrete examples of that formula in action, imagine three
    companies with slightly different risk profiles at a time when (1) the
    risk-free rate is 3% and (2) the discounted-cash-flow analysis of
    dividend-paying companies in the S&P 500 produces an expected
    return of 10%. Let’s calculate the three companies’ Returns using
    the formula above:
    •   If Company A has a completely average risk profile, its Beta
    is 1. So Company A has a Return of 10%. That’s because
    10 = 3 + 1(10 - 3).
    •   Say Company B is slightly riskier than Company A. If its
    Beta is 1.05, then its Return is 10.35%. That’s because
    10.35 = 3 + 1.05(10 - 3).
    •   Finally, say Company C is slightly safer than Company A.
    If its Beta is 0.95, then its Return is 9.65%. That’s because
    9.65 = 3 + 0.95(10 - 3).
    19
    the S&P 500; (2) its use of adjusted betas (as part of the
    formula) with a size-premium adjustment derived from
    unadjusted betas (applied after running the formula); and (3) its
    use of betas based on the market risk of the New York Stock
    Exchange with an expected market return based on the S&P
    500. We will address each individually.
    1
    For the dividend-paying S&P 500 companies that FERC
    used to determine the “expected return,” no one knows for sure
    how much they will grow. But those companies’ growth rates
    are necessary to calculate the expected return. So FERC filled
    in that blank with five-year growth projections from the
    Institutional Brokers’ Estimate System. It rejected the
    customers’ request that it average those five-year projections
    with longer-term growth projections.
    FERC adequately explained that decision. It cited
    financial research that supported the use of only short-term
    growth rates. And it explained that the short-term rates better
    reflect an investor’s expected return on an investment in the
    S&P 500 as an index. That’s because the S&P 500 is regularly
    updated to include only companies with high market
    capitalization. Further, FERC explained that the S&P 500
    includes companies at all stages of growth, so older companies
    with lower growth potential will balance out younger
    companies with higher growth potential. In light of the “great
    deference” that we afford FERC’s ratemaking analysis, that
    explanation is sufficient. See FERC v. Electric Power Supply
    Association, 
    577 U.S. 260
    , 292 (2016) (cleaned up).
    20
    2
    The second issue concerns the size-premium adjustment
    that FERC applied to the result of its formula. Ibbotson, the
    company that calculated the size premium, analyzed a large
    group of companies in the New York Stock Exchange. To
    grossly simplify, Ibbotson applied a capital-asset formula to
    those companies and then saw if there were any differences in
    the results that were best explained by size. See Frank Torchio
    & Sunita Surana, Effect of Liquidity on Size Premium and Its
    Implications for Financial Valuations, 9 J. Bus. Valuation &
    Econ. Loss Analysis 55, 56-57 (2014).
    Ibbotson used unadjusted betas in its capital-asset formula.
    But recall that FERC used adjusted betas for its capital-asset
    formula. The customers argue that FERC’s decision to use
    both despite that mismatch was irrational.
    FERC acknowledged the “imperfect correspondence”
    between the two. JA 611. But it decided that the size-premium
    adjustment sufficiently improved the capital-asset model’s
    accuracy to justify the mismatch.
    We can only judge FERC’s logic based on the evidence it
    had before it. See FCC v. Prometheus Radio Project, 
    141 S. Ct. 1150
    , 1160 (2021). Here, because FERC had a size-
    premium adjustment based on unadjusted betas and believed
    that adjusted betas were the most appropriate input to use in the
    capital-asset model, it had to choose between “imperfect
    correspondence” and no size adjustment at all. That is the kind
    of technical choice to which we are “particularly deferential.”
    Public Service Commission of Kentucky v. FERC, 
    397 F.3d 1004
    , 1006 (D.C. Cir. 2005) (quoting Time Warner
    Entertainment Co. v. FCC, 
    56 F.3d 151
    , 163 (D.C. Cir. 1995)).
    We do not find it arbitrary and capricious.
    21
    3
    That same logic persuades us to reject the challenge to
    FERC’s decision to combine adjusted betas based on the New
    York Stock Exchange with an expected return based on the
    S&P 500. Here, too, FERC acknowledged the “imperfect
    correspondence” between the New York Stock Exchange and
    the S&P 500. JA 873. But FERC concluded that it would not
    be reasonable to calculate an expected return using all 2,800
    companies in the New York Stock Exchange. And no party
    provided adjusted betas from the appropriate time frame based
    on the S&P 500. It was not arbitrary and capricious for FERC
    to do the best it could with the data it had. See Prometheus,
    141 S. Ct. at 1160.8
    C
    From there, the customers level an array of challenges to
    FERC’s creation of presumptively just and reasonable ranges
    at step one of the Section 206 analysis. Recall, if you’ll suffer
    another reminder, that FERC created ranges within the zone of
    reasonableness based on the company’s risk profile to analyze
    the step-one question of whether an existing rate is unjust and
    unreasonable. Rates within the appropriate range are presumed
    to be just and reasonable.
    1
    First, the customers argue that we did not require FERC to
    adopt its presumption scheme when we vacated FERC’s New
    8
    In a more recent proceeding FERC did have access to adjusted betas
    based on the S&P 500, so it used them. Constellation Mystic Power,
    LLC, 
    176 FERC ¶ 61,019
    , 61,102 (2021).
    22
    England opinion in Emera Maine. See 
    854 F.3d 9
     (D.C. Cir.
    2017). That is true, but it misses the point. FERC is entitled to
    adopt any methodology it believes will help it ensure that rates
    are just and reasonable, so long as it doesn’t adopt that
    methodology in an arbitrary and capricious manner. See
    Southern California Edison Co. v. FERC, 
    717 F.3d 177
    , 182
    (D.C. Cir. 2013).
    As FERC recognized, our opinion in Emera Maine held
    that FERC had failed to sufficiently explain why the existing
    rate was unjust and unreasonable at step one of the Section 206
    inquiry. 854 F.3d at 26-27. We had explained that “the zone
    of reasonableness creates a broad range of potentially lawful”
    Returns, such that FERC needed to do more than identify a
    single new Return that it preferred. Id. at 26. So in response,
    FERC developed this new framework to more effectively
    verify that an existing rate is in fact unjust and unreasonable.
    The customers have provided no persuasive reason to think that
    doing so was arbitrary and capricious.
    2
    Second, the customers contend that the presumption
    scheme unlawfully heightens the burden of proof that they
    must carry. It doesn’t. The presumption is just that: a
    presumption. FERC provided several types of evidence that
    could rebut it, from non-utility stock prices to expert testimony.
    3
    Next, the customers claim that FERC created an
    irrebuttable presumption in this particular case by using the
    Return it had set in the first-complaint proceeding to adjudicate
    the second complaint. Their argument has two layers. First,
    they argue that it was unlawful for FERC to use the new Return
    23
    (the 10.02% it had just set earlier in Opinion 569-A) instead of
    the pre-complaint 12.38% Return they had originally
    challenged. Second, they say that even if that was lawful,
    FERC’s adjudication of both proceedings in one order denied
    them any meaningful opportunity to rebut the presumption
    because they didn’t know what presumptively just and
    reasonable number they had to rebut. They are wrong on both
    fronts.
    To the first point, Section 206 says:
    Whenever the Commission, after a hearing held upon
    its own motion or upon complaint, shall find that any
    rate, charge, or classification, demanded, observed,
    charged, or collected by any public utility for any
    transmission or sale subject to the jurisdiction of the
    Commission, or that any rule, regulation, practice, or
    contract affecting such rate, charge, or classification is
    unjust, unreasonable, unduly discriminatory or
    preferential, the Commission shall determine the
    just and reasonable rate, charge, classification, rule,
    regulation, practice, or contract to be thereafter
    observed and in force, and shall fix the same by order.
    16 U.S.C. § 824e(a) (emphases added).
    Two aspects of the statute show that FERC was correct to
    use the 10.02% Return it had set earlier in Order 569-A when
    it resolved the first complaint.9 First, the statute uses the
    present-tense verb “is,” which means that FERC must look to
    the current Return at the time of decision. See Carr v. United
    9
    Although the statute uses “rate,” in this case the only component of
    the rate that was at issue was the Return, so that is what FERC
    focused on.
    24
    States, 
    560 U.S. 438
    , 447-48 (2010) (explaining the importance
    of verb tense). Second, the statute commands that FERC set a
    Return “to be thereafter observed and in force.” Once FERC
    sets a new Return in the first proceeding, it must observe and
    enforce that Return until it lawfully changes, including in
    ongoing proceedings.
    On top of those points, the customers’ theory would upend
    the strict fifteen-month refund limit that Congress placed on
    Section 206 proceedings. 16 U.S.C. § 824e(b). If customers
    can just file new complaints challenging the same Return every
    fifteen months, the limit accomplishes nothing. Absent some
    clearer indication of congressional intent, we will “not assume
    that Congress left such a gap in its scheme.” Jackson v.
    Birmingham Board of Education, 
    544 U.S. 167
    , 181 (2005).10
    To the customers’ second argument, there is some
    awkwardness in the fact that FERC chose to act on the first and
    second complaints in one order. But FERC has “broad
    discretion to manage” its docket. Florida Municipal Power
    Agency v. FERC, 
    315 F.3d 362
    , 366 (D.C. Cir. 2003) (cleaned
    up). And the customers do not point to any evidence that they
    would have marshaled to challenge the new 10.02% Return
    that they did not offer to challenge the old 12.38% one. So on
    these particular facts, we cannot conclude that FERC abused
    its broad discretion.
    10
    This should not be read to endorse the transmission owners’
    argument that customers cannot file successive complaints. FERC
    has an explanation for allowing successive complaints that it says
    reconciles the practice with this provision. Because we decide that
    FERC was correct to use the Return from the first complaint to
    adjudicate the second, and therefore that FERC was right to dismiss
    the second complaint, we need not decide this issue.
    25
    4
    The customers’ final step-one challenge says that the
    presumption unlawfully creates a difference between Section
    205 proceedings and Section 206 proceedings. But Congress
    required that difference. “Section 206’s procedures are entirely
    different and stricter than those of section 205.” See Emera
    Maine, 854 F.3d at 24 (cleaned up).
    D
    Next, remember that for step two of the Section 206
    analysis — setting the new just and reasonable rate — FERC
    returned to its customary practice of using the midpoint of the
    zone of reasonableness. The customers argue that it should
    have set aside the midpoint in favor of the median.11
    But we have already held that FERC can reasonably use
    the midpoint of the zone of reasonableness when setting a
    Return for “a diverse group of companies.” Public Service
    Commission, 
    397 F.3d at 1011
    . That decision, Public Service
    Commission of Kentucky v. FERC, even involved MISO. 
    Id. at 1006
    .
    The customers try to cabin Public Service Commission to
    Return analyses where FERC uses a proxy group made up of
    companies from within the same region as the transmission
    owners. But that was not the reason FERC chose the midpoint
    in Public Service Commission, so it is not the reason we
    deemed FERC’s choice reasonable. 
    Id.
     There, FERC focused
    11
    For a series of numbers, the midpoint is the halfway point between
    the biggest number and the smallest number (calculated by adding
    the two together and dividing by two). The median is the middle
    number in the series. So, for example, the midpoint of 1, 3, 5, 9, and
    11 is 6. The median is 5.
    26
    on “the rate’s across-the-board applicability to MISO”
    transmission owners. 
    Id. at 1011
    . FERC did the same here, so
    precedent requires that we reach the same result.
    E
    Finally, the customers challenge FERC’s about-face on the
    risk-premium model (Model 4). As FERC applied it in this
    proceeding, the model compares past Returns that FERC itself
    set or approved to contemporaneous corporate-utility-bond
    rates. FERC took the difference between those rates and added
    it to the current corporate-utility-bond rate. So for example, if
    the past corporate-utility-bond rates were always 6% and
    Return rates were always 10%, FERC would take that
    difference (4%) and add it to the current corporate-utility-bond
    rate. If the current corporate-utility-bond rate is 5%, the new
    Return would be 9%.12 See James Bonbright, Albert Danielsen
    & David Kamerschen, Principles of Public Utility Rates 323
    (2d ed. 1988) (offering a similar example).
    12
    This explanation omits one step that no one questions, which is
    therefore not relevant to our analysis. Before FERC adds the risk
    premium it calculated from the past corporate-utility-bond rates and
    Returns to the current bond rate, it adjusts that number to “reflect the
    tendency of risk premiums to rise as interest rates fall.” JA 249.
    Basically, it calculates the inverse relationship between bond yields
    and risk premiums to determine how much higher the risk premium
    needs to be to incentivize investment when the bond rate is lower.
    Here, for example, the calculation determined that for every 1% bond
    rates dropped, investors required an extra .77% Return. So when the
    bond rate had dropped by 1.35%, FERC multiplied 1.35 and .77 to
    get an adjustment of 1.04%, which it added to the average difference
    between the past bond rates and past FERC-allowed Returns. It
    then added the sum of those numbers to the current corporate-utility-
    bond rate to get the value for what the new Return should be.
    27
    In FERC’s first rehearing order, Opinion 569, it concluded
    that any “additional robustness” the risk-premium model added
    to its methodology was “outweighed by the disadvantages of
    its deficiencies.” JA 628. It then spent several pages
    demonstrating the impressive extent of those deficiencies. For
    example:
    •   The model, at least as applied in this case, “defies
    general financial logic” by keeping the Return stable
    regardless of capital-market conditions. JA 629.
    •   There was insufficient evidence in the record to
    conclude that investors rely on this kind of risk-
    premium model.
    •   The model is less accurate than the discounted-cash-
    flow model (Model 1) or capital-asset model (Model 2)
    because it relies on previous Return determinations that
    may not have been market-based.
    •   It “is largely redundant with” the capital-asset model
    (Model 2), so adding it would overweight risk-premium
    methodologies against the long-used discounted-cash-
    flow model (Model 1). JA 628.
    •   It presents “particularly direct and acute” circularity
    problems because it uses past FERC-allowed Returns
    to set the new ones. JA 628.
    And those are just from the first two pages of criticisms.
    Suffice it to say that in Opinion 569, FERC found the risk-
    premium model quite defective.
    Then, in Opinion 569-A — on rehearing of Opinion 569
    — FERC changed its tune. It decided “that the defects of the
    Risk Premium model do not outweigh the benefits of model
    diversity” after all. JA 882.
    28
    FERC is, of course, entitled to change its mind. FCC v.
    Fox Television Stations, Inc., 
    556 U.S. 502
    , 515 (2009). But to
    do so, it must provide a “reasoned explanation” for its decision
    to disregard “facts and circumstances that” justified its prior
    choice. 
    Id. at 515-16
    . Here, FERC failed to do that.
    First and worst, FERC did not explain how its changes
    brought the analysis into line with “general financial logic.” JA
    629. FERC can’t ignore the basic financial principles that
    otherwise undergird its analysis — at least not without a
    compelling explanation. See Tennessee Gas Pipeline Co. v.
    FERC, 
    926 F.2d 1206
    , 1210-11 (D.C. Cir. 1991); 
    id. at 1213
    (Thomas, J., concurring) (“At the very least, FERC was obliged
    to offer some convincing evidence in support of its facially
    implausible economic assumption”).
    Second, FERC failed to adequately explain why it no
    longer mattered that investors don’t use this model. Instead, it
    simply noted that investors expect a premium on a stock
    investment over a bond investment, and that investors track the
    Returns FERC allows. Both statements are true, but neither
    offers a persuasive reason to think that the risk-premium model
    as FERC applied it here offers meaningful insight into investor
    behavior.
    Third, FERC failed to meaningfully address its own
    concerns about the risk-premium model’s circularity. Instead,
    it just said that “all of the models contain some circularity” and
    decided that averaging the risk-premium model’s results with
    the other models’ results helps mitigate the circularity. JA 882.
    That explanation doesn’t meaningfully engage with the
    “particularly direct and acute” circularity problems presented
    by using old rates to set new ones. JA 628.
    29
    Finally, FERC never engaged with its earlier concerns
    about the overweighting of risk-premium theory. It briefly
    discussed the redundancy of the capital-asset and risk-premium
    models (Models 2 and 4), saying that because they used
    different inputs to calculate the risk premium they were not too
    redundant to use. But it failed to reckon with its own serious
    concerns about “variations of the risk premium model”
    receiving twice the weight of the discounted-cash-flow model
    (Model 1) that FERC “has long used and, over time, refined.”
    JA 628. An agency ignoring its own qualms is not reasoned
    decisionmaking.
    *    *   *
    FERC failed to offer a reasoned explanation for its
    decision to reintroduce the risk-premium model (Model 4) after
    initially, and forcefully, rejecting it. Because FERC adopted
    that significant portion of its model in an arbitrary and
    capricious fashion, the new Return produced by that model
    cannot stand. We therefore vacate FERC’s orders.
    IV
    In addition to the customers’ challenge to FERC’s new
    Return methodology, the customers challenged FERC’s
    determination that it could not order a refund for the second
    complaint’s refund period. But to the extent that any of that
    argument survives our earlier rejection of the customers’
    statutory basis for their “irrebuttable presumption” argument,
    see Part III.C.3, we decline to opine on the customers’
    argument because we have already granted their petition to
    vacate FERC’s rate orders. See Southwest Airlines Co. v.
    FERC, 
    926 F.3d 851
    , 859 (D.C. Cir. 2019).
    30
    For the same reason, we dismiss the transmission owners’
    petitions challenging those now-vacated orders. They had
    challenged FERC’s right to require transmission owners to pay
    the difference between the amount FERC ordered in its first
    decision and the rate it ordered on rehearing. But because we
    vacate FERC’s rehearing order, there is no longer a new rate to
    base a refund on.
    Until FERC sets a new Return, a decision on the refund
    issue will not alter the parties’ rights and obligations. Nor will
    a decision on the transmission owners’ argument that FERC
    lacked the authority to adjudicate the second complaint. When
    “it is not necessary to decide more, it is necessary not to decide
    more.” PDK Laboratories, Inc. v. DEA, 
    362 F.3d 786
    , 799
    (D.C. Cir. 2004) (Roberts, J., concurring in part and in the
    judgment).
    V
    We grant the customers’ petitions for review, dismiss the
    transmission owners’, vacate the underlying orders, and
    remand for FERC to reopen proceedings.