Brussels-based Geradin Partners is suing Amazon at the Competition Appeal Tribunal in the UK on behalf of an English law professor claiming damages of up to £2.7 billion ($3.41 billion) on behalf of third-party online sellers.

The damage estimate assumes more than 200,000 third-party sellers will join the claim although the exact figure won’t be known until disclosure. Sellers are automatically included in the claim unless they opt out, Geradin founding partner Damien Geradin told Law.com International.