Plaintiff event-study and loss-causation econometrician
Expert class library · Securities · Plaintiff side
Measures abnormal stock returns on corrective disclosure dates to show that the revelation of the truth caused investor losses. Builds the artificial inflation ribbon and the class-wide damages methodology.
What this expert is retained to answer
- Did the stock price fall in a statistically significant way when the truth was revealed?
- How much of each price decline is attributable to the corrective information rather than confounding news?
- What was the artificial inflation in the stock price on each day of the class period?
- Can damages be calculated with a single class-wide method consistent with the plaintiffs' theory of liability?
Methods
- Single-firm event study
- Disaggregation of confounding information
- Inflation ribbon construction
- Out-of-pocket damages model
How the testimony is attacked
- Results-driven selection of event dates. Defendants argue the expert ran the regression first and then picked dates with significant returns. In Bricklayers the defense made exactly this argument about an expert who identified 57 significant dates before tying them to the allegations.
- Excessive use of dummy variables. Removing many days from the estimation window can artificially stabilize the baseline. The Bricklayers district court, affirmed by the First Circuit, relied on prior decisions criticizing a high share of dummied-out dates.
- Failure to disaggregate confounding information. When fraud-related and unrelated news arrive together, the expert must use an accepted method, such as intraday analysis, to separate them. Bricklayers rejected an approach that attributed a rough share of each move to each report or blamed it all on the defendants.
- Inconsistency with market efficiency. Attributing price moves to information that was already public contradicts the efficient market premise that supports reliance. Bricklayers called this having it both ways.
- Unsupported adjustments to the inflation estimate. After a court narrows the case, the expert must revise inflation reliably. In Pfizer the trial court excluded the expert over a proportional reduction it found unsupported, although the Second Circuit held that one flawed step did not taint the underlying event study.
- Subjective classification of news days. Defendants argue the expert's choice of which days carry significant news is subjective. Carpenters v. Barclays treated that subjectivity as a question of weight, not admissibility, especially where the defense offered no competing event study.
What the public record shows
A deliberately narrow CourtListener search, "event study" AND "loss causation" AND (Daubert OR "Rule 702"), returned 10 opinions filed since 2015, as of October 2, 2026; broader searches return more. 7 rulings that show how courts handle this class of testimony:
| Outcome | Case | Court | Why |
|---|---|---|---|
| Sent back for review | GA Firefighters' Pension v. Anadarko Petroleum Corp.99 F.4th 770 | 5th Cir. 2024 | The Fifth Circuit held the trial court had not performed a full Daubert analysis before relying on the plaintiffs' rebuttal event study at class certification, vacated certification and sent the challenge back to be fully considered, since Daubert applies with the same rigor at class certification as at trial. |
| Exclusion reversed | Teachers' Retirement System v. Pfizer, Inc.819 F.3d 642 | 2d Cir. 2016 | Reversing the trial court, the Second Circuit vacated the exclusion of the plaintiffs' event-study expert, holding that one questionable proportional adjustment did not undermine an event study whose methodology the defense expert had not seriously disputed. |
| Admitted | In re Vivendi, S.A. Securities Litigation838 F.3d 223 | 2d Cir. 2016 | The Second Circuit held the trial court did not abuse its discretion in admitting the plaintiffs' event-study inflation and damages testimony, rejecting the argument that misstatements not tied to a price increase made the model unreliable or unhelpful. |
| Admitted | Carpenters Pension Trust Fund v. Barclays PLC310 F.R.D. 69 | S.D.N.Y. 2015 | The court denied the defendants' Daubert motion against the plaintiffs' event studies, holding that subjective judgments in such studies go to weight and noting that the defendants chose not to submit an event study of their own. |
| Excluded | Bricklayers & Trowel Trades International Pension Fund v. Credit Suisse Securities (USA) LLC752 F.3d 82 | 1st Cir. 2014 | The First Circuit upheld exclusion of the plaintiffs' loss-causation event study, which the trial court found flawed by date selection, heavy use of dummy variables, attribution of moves to already-public news, and no accepted method for separating confounding information. |
| Excluded | In re REMEC Inc. Securities Litigation702 F. Supp. 2d 1202 | S.D. Cal. 2010 | The court struck the plaintiffs' loss-causation event study at summary judgment because the regression assumed every residual return reflected fraud-related news, did not separate corrective information from other company news released the same day, and counted a non-corrective announcement. |
| Excluded | In re Williams Securities Litigation, WCG Subclass558 F.3d 1130 | 10th Cir. 2009 | The Tenth Circuit affirmed exclusion of the plaintiffs' loss-causation expert because neither his leakage theory nor his corrective-disclosure theory could separate price declines caused by revelation of the fraud from declines caused by unrelated company-specific news. |
Each case links to the free opinion text on CourtListener.
Under amended Rule 702
Since December 1, 2023, Rule 702 says expressly that the party offering an expert must show the court it is more likely than not that the testimony meets each requirement: that it rests on sufficient facts or data, uses reliable methods, and reflects a reliable application of those methods to the case. Questions about the basis of an opinion are no longer automatically matters of weight for the jury. For how the circuits have applied the amendment, see the Rule 702 tracker, which follows each court of appeals; for what that means for preparing or attacking this class of expert, see the guide on amended Rule 702.
Related classes
Guides
- Daubert Challenges to Event Studies in Securities Cases
- Price Impact at Class Certification After Goldman
- Amended Rule 702 After Nearly Three Years: What Courts Exclude
Simulating this class on a matter
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Last reviewed October 2, 2026. How this page is built: rulings are found by searching court opinions on CourtListener, and each one is read in the opinion before it is summarised here; outcomes are labelled by what the court did with the expert's testimony. No individual expert is named. This page summarises public decisions for orientation and is not legal advice; read the opinion before relying on any ruling.