There have been a number of recent developments in California State Teachers’ Retirement System & Ors v Boohoo Group PLC, one of the leading securities claims currently proceeding in the Commercial Court in England.
Following the first case management conference (CMC) in February 2026, during which Mr Justice Green ordered that reliance be determined at Trial 1 and causation and quantum at Trial 2, two further claims have been issued, adding five retail investors and a further 11 institutional investors to the proceedings. These claims will be case managed together with the original claim pursuant to the second CMC order.
While several issues had been agreed between the parties in advance of the second CMC, held on 14 July, the remaining points in dispute all related in some way to the issue of reliance. Namely: (i) the identity of the reliance sample claimants, (ii) whether econometric expert evidence should be permitted at Trial 1 to determine common/price reliance, and (iii) whether the claimants should have to provide documents mentioned in certain further particulars of reliance (FPOR), which were not already in their solicitor’s possession, prior to disclosure.
Reliance sample claimants
As a starting point, Boohoo agreed to the six sample claimants proposed by the claimants. However, it also proposed an additional seven claimants to ensure the inclusion of all claimants whose reliance questionnaires stated that a relevant individual had read “any” of the published information themselves.
Boohoo argued that because the reliance questionnaires did not identify which specific pieces of published information had been read or relied on by the individual, the existing sample may not cover all materially different reliance cases. It said it could be left open to a non-sampled claimant to tailor their case depending on the Trial 1 findings.
The claimants opposed the additional claimants on the basis that this would no longer reflect a sampling exercise and that the sample claimants it had identified already provided sufficient coverage across the relevant reliance categories, including the relevant period and the pleaded published information.
The court recognised that there was force in Boohoo having some input into the sample. The practical reality, and not as a criticism of the approach taken by the claimants, was that the claimants were likely to have selected sample claimants advantageous to their position. The first CMC order had envisaged a process by which Boohoo would have the opportunity to propose additions following the claimant’s proposal, to address this reality in the interests of fairness.
Mr Justice Green was not, however, prepared to add every claimant in a particular category as proposed by Boohoo. As a middle ground, and with proportionality in mind, he ordered the addition of three further sample claimants, selected by reference to claim value.
Econometric expert evidence
The second issue to be determined was whether to grant the claimants’ request for permission to adduce econometric expert evidence at Trial 1 to determine common/price reliance.
Boohoo opposed this evidence. It proposed that the court should proceed, for the purposes of Trial 1, on the assumption that the market in Boohoo shares was efficient and that at least some published information influenced the share price at some point during the relevant period.
The claimants argued that these assumptions fell short of the admissions required to prevent Boohoo from resurrecting at Trial 2 arguments that specific statements or omissions did not, in fact, affect the share price or cause loss.
The court ultimately decided that common reliance should be determined on the basis of evidence rather than assumptions and therefore granted the permission sought by the claimants. The cost of such expert evidence was considered proportionate in the context of the litigation.
Mr Justice Green made clear that any overlap that this would generate with what would then need to be determined for causation at Trial 2 was a consequence of Boohoo’s position that reliance should be tried at Trial 1.
Documents mentioned in the further particulars of reliance
Boohoo also sought early production of documents mentioned in the FPOR of certain sample claimants. Boohoo argued that the documents would assist it in responding to the claimants’ Section 2 Disclosure Review Documents (DRDs), considering appropriate keywords and refining disclosure searches.
The claimants had agreed to provide documents already in their solicitor’s possession. However, they objected to undertaking a separate exercise to obtain any others, given that disclosure of those documents would be due in any event by 30 October 2026.
The court declined to grant the order Boohoo was seeking. Mr Justice Green considered the request unnecessary at this stage and was not persuaded that the documents would materially assist the disclosure process.
Comment
The issues in dispute between the parties at the second CMC on Boohoo clearly demonstrate the growing importance of reliance in litigation under section 90A/Schedule 10A of the Financial Services and Markets Act 2000.
In deciding the sample claimants, Boohoo’s focus was not simply on the number of claimants. It was also to ensure that all claimants who had personally read published information and might raise materially different reliance issues were included. However, as the court observed, choosing all defeats the purpose and benefit of sampling. While Boohoo was given some input into the sample selection process, its underlying concern will remain, particularly in light of additional claimants having been added who have not yet provided reliance questionnaires.
The expert evidence decision meanwhile illustrates the practical difficulty of separating reliance from causation in a split trial. Mr Justice Green’s decision suggests that where reliance is to be determined at Trial 1, the court may be reluctant to proceed on assumptions that leave open the possibility of relitigating overlapping factual issues at Trial 2.
Similar questions have recently arisen in Entain, where the court considered the interaction between reliance and causation and the difficulty of separating them across two separate trials. The decision in Boohoo to have reliance in Trial 1 is an outlier, and it highlights the practical difficulties of splitting reliance and causation. For larger cases, the norm of reliance and causation being in Trial 2 will likely prevail.
