title: Reindexing pandas_datareader df into quarterly giving random NaN's
body: <p>I'm trying to resample pandas_datareader price data dfs into quarterly (from either monthly or daily), and daily is giving me sporadic NaN's (across all instruments), and monthly is giving me ALL NaN's.  End goal is a dataframe with just quarterly return.
  Tried it with yfinance and pdr, both throw nans.  Even YF on 3mo interval gives me every other NaN  -- what am I missing here?</p>
  
  <pre><code>#sp = yf.download("SPY", start='2017-01-01', end="2020-01-30",interval='3mo').drop(columns=['Open','High','Low','Close','Volume'])
  sp = pdr.DataReader('SPY','yahoo',start='2017-01-01').drop(columns=['Open','High','Low','Close','Volume'])
  #Get slightly different NaNs, but NaNs with both datasets.
  
  sp.reset_index(inplace=True)
  sp = sp.set_index('Date').asfreq('q').reset_index()
  #sp['Adj Close'].pct_change() #Gives me NaNs on same the Adj Close rows regardless of calc
  sp
  
  
  #To show that data is in tact, this operation is flawed somehow.
  spy_base = pdr.DataReader('SPY','yahoo','2017-01-01')
  spy_base.loc[spy_base['Date'].dt.strftime('%Y-%m-%d').str.startswith('2018')]
  
  #OR simply
  s = pdr.DataReader('SPY','yahoo','2018-01-01','2019-01-01')
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/I58cv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/I58cv.png" alt="enter image description here"></a></p>