California State Teachers' Retirement System & Ors v Boohoo Group Plc

In complex investor litigation using a split trial, sample claimants should provide broad coverage of materially different reliance cases without reproducing every claimant or variation. Further samples may be added where selected on a rational and proportionate basis, but including all claimants in one category defeats the purpose of sampling.

Where market-price reliance is a live issue, the court should determine whether specific published information influenced the share price by reference to real evidence. A general assumption about listed securities is insufficient. Relevant expert evidence may therefore be permitted at the trial where reliance is decided. Disclosure of reliance documents may be refused as unnecessary or premature where full disclosure is imminent.

Investors brought claims against an e-commerce retailer under the Financial Services and Markets Act 2000, section 90A and Schedule 10A. A first case management conference ordered a split trial, with reliance included in Trial 1 and causation and quantum excluded.

At this second case management conference, the court considered the identity of sample claimants, permission for corporate broking and econometric expert evidence, and a request for documents referred to in reliance forms under CPR PD 57AD, paragraph 21.1. The central questions were how reliance could fairly be sampled, whether market-price reliance required expert evidence, and whether the requested documents were necessary before full disclosure.

Mr Justice Green determined three case-management issues.

1. Sample claimants. Drawing on Various Claimants v Standard Chartered plc [2024] EWHC 3199 (Ch), Various Claimants v G4S Limited (formerly G4S PLC) [2022] EWHC 1742 (Ch) and Various Claimants v Serco Group plc [2023] EWHC 119 (Ch), the judge held that sampling should avoid repetitive evidence and provide guidance to the wider claimant group. It need not capture every difference. Including all claimants who selected one reliance category would defeat the purpose of sampling. The judge accepted the addition of two rationally selected claimants with significant claims and directed that SC8 and SC9 be added. Particular details of the published information relied on were not essential for selecting the samples, although they would be needed in due course.
2. Expert evidence. Corporate broking evidence was permitted because it would assist the court and the issues had been agreed. Econometric evidence was also permitted. Common or market-price reliance was to be tried in Trial 1, and the relevant questions included market efficiency and whether the specific published information influenced the share price. A general assumption that public information influences listed securities was insufficient. The observation in Allianz Global Investors GmbH and Ors v RSA Insurance Group Ltd (formerly RSA Insurance Group Plc) [2021] EWHC 3091 (Ch) did not remove the need for real evidence. The possible overlap with causation did not justify postponing the evidence, and the substantive legal adequacy of the reliance case was not finally determined at this hearing.
3. Disclosure. The request under PD 57AD, paragraph 21.1, was unnecessary and premature. The claimants had agreed to provide documents in their solicitors’ current possession, while full disclosure, including the wider category sought, was due on 30 October 2026. No further order was made.
4. Orders. SC8 and SC9 were added as sample claimants. Permission was granted for both forms of expert evidence. The defendant’s wider document request was refused.

This was a further case-management hearing in the same proceedings. The judgment records the first CMC on 9 and 10 February 2026 and the earlier judgment at [2026] EWHC 335 (Comm) . No appeal is stated.