Key Takeaway British American Tobacco writes down $31.5 billion as it shifts its business away from cigarettes. Shares of British American Tobacco tumbled Wednesday after the owner of Camel and American Spirit cigarettes took an impairment charge of about $31.5 billion, mainly related to its struggling U.S. cigarette brands with the number of people who smoke in steep decline. In a financial update, London-based British American Tobacco said it is in the process of transforming its business …

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