-17. 
Instead, we
remanded so that the district court could determine “whether the Janik
Report”—the only lost-profits evidence in the record—“is admissible, and if it
is admissible, whether it establishes lost profits with reasonable certainty.”
 Id.
at 817.

       1  We explicitly acknowledged both that “Jacked Up likely could have claimed reliance
damages” as an alternative to lost profits and that “counsel for Jacked Up stated at oral
argument that Jacked Up does have reliance damages.”
 Id. at 816 
n.14. We concluded,
however, that “such damages are not substantiated in the record or explained in Jacked Up’s
briefs.”
 Id.
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                                       No. 19-10391
                                              B.
       On remand, the district court concluded that the Janik Report was not
admissible because it was not “based on sufficient facts or data.” Fed. R. Evid.
702. 2 According to the district court, the Janik Report assumed the accuracy of
a set of projections prepared by Sara Lee regarding future sales of Jacked Up
products, which were set out in a document called the Sara Lee Pro Forma.
E.J. Janik, a certified public accountant, then used those projections to
estimate Jacked Up’s lost profits. The district court was troubled by the fact
that Janik did not “conduct[] an independent determination of whether the
Sara Lee Pro Forma’s projections were valid or reasonable,” because it believed
that “a company’s financial projections are not automatically reliable, such
that an expert may rely on the projections without further inquiry or
explanation.”
       Additionally, “evidence presented by Sara Lee”—and credited by the
district court—“contradict[ed] Jacked Up’s contention that Sara Lee’s Pro
Forma [wa]s objectively reliable.” The district court relied heavily on a
declaration signed by Greg Immell, Sara Lee’s Director of Marketing for
Beverage Products in 2011, which explained why the Sara Lee Pro Forma was
“an unlikely prediction of the Jacked Up product’s success.” Per Immell:
              41. Prior to any final agreement with Jacked Up, Sara
       Lee’s senior management had to approve the concept of a
       relationship with Jacked Up. That meant creating a business case,
       which would consist of one or more pro forma projections. To create
       a pro forma projection, the business team, with input from sales
       and also from Jacked Up, would have to put together its best guess
       as to how a Jacked Up energy iced tea would perform in the


       2 The admissibility of the Janik Report, as a non-dispositive matter, was “referred to
a magistrate judge to hear and decide,” Fed. R. Civ. P. 72(a), and the district court affirmed
the magistrate judge’s decision under a “clearly erroneous or contrary to law” standard, 28
U.S.C. § 636(b)(1)(A). Because it is does not affect our resolution of this appeal, we otherwise
elide the distinction between the district court and the magistrate judge.
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                            No. 19-10391
 marketplace over the life of a potential agreement with Jacked Up.
 A pro forma projection also helps me decide whether to even
 seriously consider moving forward with the new product.
       42. It is my usual practice to prepare three pro formas: a
 conservative scenario, a middle scenario, and an aggressive
 scenario. . . .
       43. Jonathan Drake, then a senior executive within the
 foodservice and beverage division, had asked for a gangbusters
 scenario to understand the greatest impact if all of [Jacked Up’s]
 and Sara Lee[’s] sales enthusiasm were to come to fruition. . . .
      44. I have reviewed [the Sara Lee Pro Forma]. I recognize
 that pro forma as being the most aggressive, “gangbusters”
 scenario . . . .
        45. There are four important things to note about the pro
 formas Sara Lee prepared. First, until there is an actual market
 test of the product, the assumptions in the pro formas are merely
 elaborate guesswork by the business and sales teams. . . .
       46. Second, a pro forma is merely the first and very
 preliminary step in the evaluation process of a new product
 opportunity. After the market test, and after there were specific
 and verifiable cost figures to utilize instead of mere assumptions,
 there would be a second, far more rigorous and comprehensive
 analysis . . . . In other words, a pro forma was only used by Sara
 Lee to understand the high level financials of a product
 opportunity; it is not a business plan or a financial projection upon
 which Sara Lee would rely. . . .
        47. Third, for the pro formas in this case specifically, we
 were missing some key information, and therefore the pro formas
 were particularly high level and based on numerous assumptions.
 . . . The best the pro forma could do was target an estimated
 margin; all ultimate price and cost figures would have only been
 determined via negotiations and market conditions.
       48. Lastly, another important but unverified factor in
 these pro formas was information received from [Jacked Up], and
 in particular information about Jacked Up’s supposed broad-based
 customer network. . . . I believe that some of [Jacked Up’s]
 boastfulness and puffery filtered into the pro formas . . . .


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                                 No. 19-10391
Because Janik did not explain his decision to use the projections in the Sara
Lee Pro Forma and because it considered the Sara Lee Pro Forma to be
unreliable, the district court decided that the Janik Report was not admissible.
                                       C.
      Following the district court’s determination that the Janik Report was
not admissible, Sara Lee moved for summary judgment on Jacked Up’s
remaining claims, arguing that Jacked Up had no admissible evidence
establishing lost profits. In response, Jacked Up submitted a declaration and
damages calculation prepared by its owner, Joseph Schmitz. Sara Lee moved
to strike that declaration, asserting that Jacked Up violated the Federal Rules
of Civil Procedure by failing to timely disclose the evidentiary material
underlying its damages computation. See Fed. R. Civ. P. 26(a)(1)(A)(iii).
      The district court granted Sara Lee’s motion to strike. Because it
believed that it was required to effect our mandate and to do nothing else, the
district court refused to consider the additional evidence put forward by Jacked
Up on remand. Alternatively, the district court stated that it would not
consider the Schmitz Declaration even if it were permitted to do so, because:
(i) Jacked Up violated Rule 26(a)(1)(A)(iii) by failing to timely disclose
Schmitz’s damages calculation; (ii) Jacked Up did not explain—much less
justify—that violation; and (iii) that violation was not harmless.
      The district court also granted Sara Lee’s motion for summary judgment.
Since the Janik Report was not admissible, the district court concluded that
the summary-judgment record did not contain any competent evidence as to
lost profits, the only kind of damages sought by Jacked Up. Consequently, the
district court granted summary judgment to Sara Lee. Jacked Up filed a timely
notice of appeal.




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                                  No. 19-10391
                                        II.
      We review district-court determinations regarding the admissibility of
expert evidence under Daubert v. Merrell Dow Pharmaceuticals, Inc., 
509 U.S.
579 
(1993) for abuse of discretion. Knight v. Kirby Inland Marine, Inc., 
482
F.3d 347
, 351 (5th Cir. 2007). A decision is an abuse of discretion if it “is based
on an erroneous view of the law or a clearly erroneous assessment of the
evidence.”
 Id. (quoting Bocanegra 
v. Vicmar Servs., Inc., 
320 F.3d 581
, 584 (5th
Cir. 2003)). The same standard applies when reviewing an admissibility
determination as part of an appeal from a grant of summary judgment. See
Christophersen v. Allied-Signal Corp., 
939 F.2d 1106
, 1109 (5th Cir. 1991) (en
banc), abrogated on other grounds by 
Daubert, 509 U.S. at 587 
& n.5.
      A de novo standard of review applies to a district court’s interpretation
of a remand order. Gen. Universal Sys., Inc. v. HAL, Inc., 
500 F.3d 444
, 453
(5th Cir. 2007). Likewise, we review de novo a district court’s decision to grant
summary judgment. 
Christophersen, 939 F.2d at 1109
.
                                       III.
      The district court did not abuse its discretion when it determined that
the Janik Report was not admissible, and our prior decision remanding this
case did not allow the district court to reopen the summary-judgment record.
It follows that the district court correctly granted summary judgment to Sara
Lee. Accordingly, we AFFIRM.
                                        A.
      The district court did not abuse its discretion when it held that the Janik
Report was inadmissible. The proponent of expert evidence must prove, by a
preponderance, that the evidence is reliable. MM Steele, L.P. v. JSW Steel
(USA) Inc., 
806 F.3d 835
, 850 (5th Cir. 2015). The reliability inquiry extends
“to all aspects of an expert’s testimony,” including “the methodology, the facts
underlying the expert’s opinion, the link between the facts and the conclusion,
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                                 No. 19-10391
et alia.” 
Knight, 482 F.3d at 355 
(citation omitted). Expert evidence that is not
“reliable at each and every step” is not admissible.
 Id.
      Although the 
basis of an expert’s opinion usually goes to the weight and
not the admissibility of expert testimony, in some cases “the source upon which
an expert’s opinion relies is of such little weight that the jury should not be
permitted to receive that opinion.” Viterbo v. Dow Chem. Co., 
826 F.2d 420
, 422
(5th Cir. 1987); accord Fair v. Allen, 
669 F.3d 601
, 607 (5th Cir. 2012). In the
words of the Third Circuit, the “suggestion that the reasonableness of an
expert’s reliance on facts or data to form his opinion is somehow an
inappropriate inquiry under Rule 702 results from an unduly myopic
interpretation of Rule 702 and ignores the mandate of Daubert that the district
court must act as a gatekeeper.” ZF Meritor, LLC v. Eaton Corp., 
696 F.3d 254
,
294 (3d Cir. 2012). “In some circumstances, an expert might be able to rely on
the estimates of others in constructing a hypothetical reality, but to do so, the
expert must explain why he relied on such estimates and must demonstrate
why he believed the estimates were reliable.”
 Id. at 292; 
accord Diabetes Ctrs.
of Am., Inc. v. Healthpia Am., Inc., No. H-06-3457, 
2008 WL 375505
, at *2 (S.D.
Tex. Feb. 11, 2008) (Atlas, J.) (“The Federal Rules of Evidence and the
requirements of Daubert are not satisfied where, as here, the expert fails to
show any basis for believing someone else’s projections.”).
      Applying this principle, the Third Circuit affirmed the exclusion of a lost-
profits expert where the expert’s opinion was based on internal financial
projections of “a nascent company, the assumptions underlying which were
relatively unknown” to the expert. ZF 
Meritor, 696 F.3d at 293
. The Tenth
Circuit, albeit applying Rule 703 and not Rule 702, similarly concluded that
testimony from a lost-profits expert who based his analysis on someone else’s
sales projections was inadmissible since “the expert failed to demonstrate any
basis for concluding that another individual’s opinion on a subjective financial
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                                 No. 19-10391
prediction was reliable, other than the fact that it was the opinion of someone
he believed to be an expert who had a financial interest in making an accurate
prediction.” TK-7 Corp. v. Estate of Barbouti, 
993 F.2d 722
, 732 (10th Cir.
1993).
      The Janik Report does not contain a word regarding the reliability of the
Sara Lee Pro Forma or its preparation. Instead, Janik seems to have assumed
that the projections in the Sara Lee Pro Forma were correct and then
extrapolated lost-profits figures. Jacked Up attempts to show that Janik
meaningfully evaluated the Sara Lee Pro Forma, but those attempts smack of
post hoc rationalization. Essentially, Jacked Up points to boilerplate
recitations in the Janik Report listing materials “reviewed and/or considered.”
Jacked Up then looks to those materials and makes confident claims about
what Janik might have used those materials to conclude. This sort of
supposition is not enough to show that the district court clearly erred when it
concluded that Janik did not evaluate the projections in the Sara Lee Pro
Forma. Similarly, Jacked Up does not point to any record evidence indicating
that the district court clearly erred by crediting Immell’s declaration regarding
the provenance—and, hence, the unreliability—of the Sara Lee Pro Forma.
Consequently, we conclude that the district court did not abuse its discretion
in excluding the Janik Report.
                                       B.
      The district court correctly construed our mandate and granted
summary judgment. Following remand, a district court must implement the
letter and spirit of the appellate mandate. Perez v. Stephens, 
784 F.3d 276
, 280
(5th Cir. 2015). “The mandate rule requires a district court on remand to effect
our mandate and to do nothing else.” Gen. Universal 
Sys., 500 F.3d at 453
(quoting United States v. Castillo, 
179 F.3d 321
, 329 (5th Cir. 1999), rev’d on
other grounds, 
530 U.S. 120 
(2000)); cf. United States v. Marmolejo, 
139 F.3d
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                                  No. 19-10391
528, 531 (5th Cir. 1998) (“The fact that the appellate court did not expressly
limit the scope of the remand order did not imply that a full blown sentencing
hearing was permissible for a second time, allowing evidence on all issues that
would affect the sentencing guidelines. . . . In short, the resentencing court can
consider whatever this court directs—no more, no less.”). Limiting the scope of
remand in this way is sensible because “[r]emand is not the time to bring new
issues that could have been raised initially.” ODonnell v. Goodhart, 
900 F.3d
220
, 225 (5th Cir. 2018); see Gen. Universal 
Sys., 500 F.3d at 453
.
      We gave the district court specific and explicit instructions regarding
how to proceed on remand: “We leave it to the district court to determine
whether the Janik Report is admissible, and if it is admissible, whether it
establishes lost profits with reasonable certainty.” Jacked 
Up, 854 F.3d at 817
.
These instructions were focused on the Janik Report and did not allow the
district court to consider additional issues, such as: (i) whether evidence in the
summary-judgement record, other than the Janik Report, could establish
Jacked Up’s lost profits; (ii) whether new evidence could establish Jacked Up’s
lost profits; or (iii) whether Jacked Up could pursue reliance or nominal
damages. See Henderson v. Stalder, 
407 F.3d 351
, 354 (5th Cir. 2005) (“Where,
as here, further proceedings in the district court are specified in the mandate
of the Court of Appeals, the district court is limited to holding such as are
directed.” (quoting Crowe v. Smith, 
261 F.3d 558
, 562 (5th Cir. 2001))). Thus,
the district court did not err when it refused to consider new damages theories
or damages evidence other than the Janik Report, and correlatively, it was
proper for the district court to grant summary judgment to Sara Lee.
                                       IV.
      For the foregoing reasons, we AFFIRM the judgment of the district court.




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