(Bloomberg) -- British American Tobacco Plc is writing down some of its US cigarette brands by about £25 billion ($31.5 billion), sending shares to the biggest decline in almost four years.Most Read from BloombergBiden Says He Might Not Have Sought Reelection If Trump Weren’t RunningTreasury Frenzy Drives 10-Year Yield Below 4.2%: Markets WrapTruck-Stop Billionaire Fights Warren Buffett to Increase $18 Billion Fortune India Stock Value Tops $4 Trillion, Narrowing Gap With Hong KongPutin Makes Ra