diff --git a/empyrical/stats.py b/empyrical/stats.py
index <HASH>..<HASH> 100644
--- a/empyrical/stats.py
+++ b/empyrical/stats.py
@@ -714,7 +714,8 @@ def beta(returns, factor_returns, risk_free=0.0):
     if np.absolute(joint.var().iloc[1]) < 1.0e-30:
         return np.nan
 
-    return np.cov(joint.values.T, ddof=0)[0, 1] / np.var(joint.iloc[:, 1])
+    cov = np.cov(joint.values.T, ddof=0)
+    return cov[0, 1] / cov[1, 1]
 
 
 def stability_of_timeseries(returns):
MAINT Beta calculation does not require explicity variance calculation.