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

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.