text: Title: web.DataReader + "fred": Failed Downloads
  Body: Running this in jupyter notebook:
  
  start = datetime.date.today() - datetime.timedelta(days=5 * 365)
  end = datetime.date.today()
  df = web.DataReader(["sp500", "NASDAQCOM", "CBBTCUSD"], "fred", start, end)
  
  Gives me this error:
  
  [*********************100%%**********************]  3 of 3 completed
  
  3 Failed downloads:
  ['CBBTCUSD', 'NASDAQCOM', 'SP500']: Exception('%ticker%: No timezone found, symbol may be delisted')
  
  What can I do to fix it?