If you bought a 20 year Treasury in Nov 1999 and held to maturity, you would have beat the S&P by 0.62%

by OpeningSpeech1

S&P CAGR calc used

Treasury’s reported yield curves for 1999

I’m completely shocked that holding a T-Bond to maturity beat the S&P over any period not starting when Volker hit the brakes. Risk adjusted the S&P is waaaaaay in the negative if you were to use the 20y as your risk free rate (IDK if that would make sense, but it might considering a “buy and hold” long term strategy).

EDIT: Too lazy to do a backtest with reinvestment that matches duration, but Portolfio Visualizer has holding a portfolio of 100% “long term Treasuries” compounding at 7.3% since Dec 31, 1999 (but that’s holding more 20y’s right now). Given the spread between 10 and 20 year Treasuries over that time it’s probably between 6% and 7%.