import pandas as pd
from pandas_datareader import data as web
import numpy as np

tickers={'stock':['AAPL', 'GOOGL', 'TSLA'], 'quantity': [50, 100,300]}
df=pd.DataFrame(tickers)
stock_prices=web.DataReader(['AAPL', 'GOOGL', 'TSLA'], data_source='yahoo', start='2017-01-01', end='2020-01-01')['Close']
#add an empy column

stock_prices["Ptf_Value"] = ""