Inside this AllianceBernstein post about the more complex concepts of levering bonds and risk parity strategies, there was a reminder about simple portfolio construction. For a very long time now, holding both stocks and bonds has been considered a “balanced” portfolio. Why is this? Because stocks and bond returns tend to move in opposite directions.
This behavior can be summed up using the finance term Beta. The 5-year rolling average beta of the S&P 500 return to the 10-year US Treasury return has consistently ranged from negative 0.1 to negative 0.3 over the past decade. This means that when when stocks went up, bonds tended to go down (but not too far down). When stocks went down, bonds tended to go up (but not too far up).
Always good to have a reminder of the benefit of holding both stocks and bonds.