title: Correlation matrix between stocks problem, data not passed correctly
body: <p>I'm doing a correlation matrix between FANG stocks but at the very last part something is not working in my returns. Here's the code:</p>
  <pre><code>import numpy as np 
  import pandas as pd
  import pandas_datareader as fyf
  
  stocks = 'FB AMZN NFLX GOOG'
  
  stocks = stocks.split()
  
  data = fyf.data.get_data_yahoo(stocks, start ='2020-06-01', end = '2020-06-15')['Close']
  
  import matplotlib.pyplot as plt
  %matplotlib inline
  
  returns = pd.DataFrame()
  for stock in data:
      if stock not in data: 
          returns[stock] = np.log(data[stock]).diff()
          
  returns = returns[1:]
  returns.corr()
  </code></pre>
  <p>I used <code>returns.head()</code> to see if it even made the table but it was not, I don't know what I'm doing wrong. Thanks for the help.</p>