https://www.blackrockblog.com/2018/01/2 ... paign=hero
"The correlation between stocks and bonds tends to move with nominal growth, the sum of real growth and inflation...
Besides growth and inflation...stock-bond correlations have had a positive correlation with the real-federal funds rate (effective federal funds rate minus the consumer price index)"
https://www.blackrockblog.com/2017/07/2 ... rrelation/
"When stock-bond correlations are presumed to be negative, portfolio construction favors traditional Treasury bonds—particularly long-dated ones—as a good source of both carry and diversification. When stock-bond correlations are positive, other hedges—notably cash—may be preferable."