What If the Stock Market Were a Bond? – Update

Here’s an update to one of my more off-the-wall ideas. I was curious to see what the historical performance of the stock market looks like, but in the form of a bond.

Crazy? Let me explain.

I took all of the historical market performance of the S&P 500 (including dividends) and invented a hypothetical long-term bond that matched the market’s monthly gains step-for-step.

I assumed that it’s a bond of infinite maturity and pays a fixed coupon each month.

There’s one hitch, though. I have to choose a starting yield-to-maturity for the beginning of the data series in December 1925. So this isn’t a completely kosher experiment because the starting point is based on my guess.

If I choose a number that’s too high, the historical performance won’t be able to keep up, and the yield-to-maturity would grow higher and higher and soon leave orbit. Conversely, if my starting YTM is too low, the yield would gradually get pushed down to microscopic levels.

Fortunately, the data makes my job easy. After 85 years, the window I have to work with is pretty narrow. Starting with 6.6% is too high, and 6.4% is too low. After playing with the numbers, I finally settled on 6.502%.

Even though this “bond” is completely make-believe, it reflects what the actual stock market really did for the past 85 years. Through the end of October, the yield stood at 12.05%.

Posted by on November 10th, 2010 at 1:01 pm

The information in this blog post represents my own opinions and does not contain a recommendation for any particular security or investment. I or my affiliates may hold positions or other interests in securities mentioned in the Blog, please see my Disclaimer page for my full disclaimer.