Companies owned by Russian billionaire Oleg Deripaska (above) have warned that US sanctions against his Russian aluminium and energy empire would have a “materially adverse impact” on future business prospects and could result in technical credit defaults. Photograph: Olga Maltseva/AFP/Getty Images

Companies owned by Russian billionaire Oleg Deripaska warned that US sanctions against his Russian aluminium and energy empire would have a “materiall(...)