Note:
It seems like that the 'iex' source is having issues. Instead, you could use 'stooq' (https://stooq.com/t/) as a source. That is: df = web.DataReader(ticker, 'stooq', start, end). The column names of the 'stooq' output are capitalized. Make sure to take this into account when altering the code.
For more information regarding the pandas data reader function:
https://pandas-datareader.readthedocs...
If there are any unclarities, please do not hesitate to send me message or leave a comment!