Covariance is a statistical measure of the extent that 2 variables move together relative to their respective mean (or average) values.
Since the bottom fell out of the stock market in 2008, investors have been shifting money from stocks into bond funds. Since 2007, there have been $1.39 trillion invested in Bond Funds versus $193 billion in stock funds. The most logical explanation is an attempt to find income and safety, but are bonds truly safe?