gistfile1.txt

start = dt.datetime(20XX, 1, 1)
end = dt.datetime.now()
    
for ticker in tickers:
    if not os.path.exists('stock_dfs/{}.csv'.format(ticker)):
        df = pdr.DataReader(ticker.replace('.', '-'), 'yahoo', start, end)
        df.reset_index(inplace=True)
        df.set_index("Date", inplace=True)
        df.to_csv('stock_dfs/{}.csv'.format(ticker))
    else:
        print('Already have {}'.format(ticker))