Shares in British American Tobacco (BAT), which makes Camel, Dunhill, and Lucky Strike and other cigarettes, plunged to their lowest level in more than four years on news of a possible ban on menthol cigarettes in the US, which would eliminate products such as Newport that generate up to a quarter of the company’s profit.

British American Tobacco reached agreement to buy full control of Reynolds American with a sweetened $49.4bn (€46.3bn) offer, bringing a successful end to almost three months of bartering with the maker of Camel cigarettes.

British American Tobacco (BAT) has offered to buy out US cigarette maker Reynolds American in a $47bn (€43bn) takeover that would create the world’s biggest listed tobacco company, with brands including Newport, Lucky Strike, and Pall Mall.