[jond2062]

Although it may spark some interesting conversation and debate, this chart isn't really all that relevant in light of modern portfolio theory and asset allocation. While I don't disagree with the data itself, the premise that a reasonable retirement portfolio would include a single mutual fund (or ETF) that is composed of 100% stocks, not to mention the fact that they are primarily large-cap growth stocks (the S&P 500), is illogical at best.

Not only should a retirement portfolio be exposed to a much wider range of risk factors than simply large-cap U.S. growth/blend stocks (bonds, TIPS, international stocks, REITs, small-cap value, etc.), but holding only a single asset class eliminates the possibility for an investor to rebalance their portfolio to maintain an appropriate asset allocation that is in line with their ability, willingess, and need to take risk (not to mention the fact that rebalancing, by definition, requires an investor to sell investments that have increased in price and purchase those that have decreased in price).

In my opinion, a more interesting chart is The Callan Periodic Table of Investment Returns: http://www.callan.com/research/download/?file=periodic/free/...

Quite simply it demonstrates that the performance of different asset classes relative to each other can change drastically from one year to the next. It would actually be a much better chart if it included more asset classes, but at the very least it shows that returns are unpredictable in the near-term and that diversification doesn't simply mean holding a bunch of stocks (especially when they are all large-cap U.S. growth/blend like the S&P 500).

[kenjackson]

I do think this is still pretty relevant. I'm not a portfolio theorist, but I believe a lot of modern asset allocation is structured around risk of short-term liquidity. That is why allocation becomes more stock heavy as you have more years until retirement (for retirement accounts).

I think a lot of people would say, "if you gave me 50 years, and a five year window in which to divest, you should definitely go all stock". I don't think that would be absurdly controversial. Looking at this data though, given the risk, it actually isn't a slam dunk.

Now this isn't to say that one shouldn't diversify among equities, but I suspect you'd see similar charts for random selection diversified among mutual funds/indices.

[jond2062]

What you are referring to is known as the "glide path." An investor in the early accumulation years starts off with a high allocation to equities and reduces it over time as they gets closer to retirement (thus reducing risk, in theory). However, I'm not sure I understand your comment as this concept that you are referring to is part of the point that I was trying to make.

What happens specifically to the S&P 500 would not be the primary concern for an investor whose portfolio consists of a wide variety of asset classes and who follows a glide path approach by reducing their allocation to stocks (and increasing their allocation to bonds) over time. Thus an investor using this approach would not be 100% invested in the S&P 500 at the beginning or the end horizon (or at any point in between) of their investment.

I guess my point is that even just adjusting this data to include a 60%/40% equity/bond portfolio, rebalanced annually would be a heck of a lot more useful for retirement planning.