Deloitte is a multinational professional-services network based in London. It is one of the Big Four accounting firms, alongside EY, KPMG and PwC, and provides services including audit, consulting, financial advisory, risk, tax and legal services.

BBC Panorama, working with the Bureau of Investigative Journalism, reported that Roman Abramovich’s advisers helped hide his wealth with assistance from Deloitte. The supplied reporting context does not specify the nature of that assistance.