The Competition Appeal Tribunal has refused Amazon’s application to vary the opt-out collective proceedings order in Professor Andreas Stephan’s merchant class action, giving its written reasons on Tuesday ([2026] CAT 84).
The order therefore stays as made on 27 November 2025, with the whole merchant class proceeding on an opt-out basis. Trial 1 remains fixed to begin on 25 April 2028, with a provisional estimate of eight weeks.
Amazon had asked the tribunal under rule 85(1) of the Competition Appeal Tribunal Rules 2015 to exclude from the opt-out class every merchant with “Gross Merchandise Sales” of more than £10m over the relevant period. Those merchants would have had to opt in to pursue their claims ([5]).
The tribunal, chaired by Sir Peter Roth with Charles Bankes and Keith Derbyshire, heard argument on 7 and 8 September. It announced at the end of the hearing that the application would be refused, with reasons to follow ([6]).
Amazon accepted that the excluded merchants’ claims could be pursued collectively. The tribunal described the proposal as one that would give the proceedings a “hybrid character”, opt-out for all but the excluded merchants and opt-in for them ([5]).
It was common ground that the tribunal could not vary the order on that basis then and there. The litigation funding agreement and the after-the-event insurance policy considered at certification covered only opt-out proceedings, so a hybrid structure would have needed an amended or supplementary funding agreement and revised insurance ([5]).
On Amazon’s evidence, the excluded group would be about the top 1,000 merchants by sales on the marketplace, out of a class of around 214,000. Amazon’s witness put their combined share at just over 40% of total gross merchandise sales ([60], [63]).
Amazon’s counsel, Daniel Piccinin KC, submitted that the Supreme Court’s decision in Evans v Barclays Bank plc [2025] UKSC 48 established clear principles. He argued that it was practicable for high-value merchants to bring their claims on an opt-in basis ([61], [63]).
The tribunal’s judgment of 24 July 2025 had granted Stephan’s application under section 47B of the Competition Act 1998. Amazon’s argument that certification should be opt-in was rejected, and it reserved the right to apply again once the Supreme Court ruled in Evans ([1], [17], [20]).
The Court of Appeal dismissed Amazon’s appeal against certification on 26 February. Amazon had not sought to appeal the decision to certify the claim on an opt-out basis ([19]).
The Supreme Court gave judgment in Evans on 18 December 2025. It reversed the Court of Appeal and restored the tribunal’s decision, and Amazon applied to vary the order after that ruling ([5], [22], [31]).
The opt-out period expired on 27 February. Only two members of the merchant class had opted out ([3]).
The tribunal said that Amazon’s application was the fifth post-Evans decision of its kind to be considered. It dismissed Apple’s application to decertify the Ennis class, and refused Google’s rule 85 application in Rodger. It certified the Microsoft class on an entirely opt-out basis in a judgment of 21 April ([43], [47], [50], [55]).
A separate action brought by Robert Hammond for a class of consumers is being case managed with the Stephan Action. Its order, also opt-out, was made on 27 November 2025 ([3], [4]).
The tribunal directed a split trial on 15 July. Trial 1 will cover market definition, dominance and abuse. A later Trial 2 will address causation, quantum and pass-on between merchants and consumers ([4]).
Kieron Beal KC and Christopher Monaghan, instructed by Geradin Partners, appeared for Stephan. Daniel Piccinin KC and Kristina Lukacova, instructed by Covington & Burling LLP, appeared for Amazon.