Earlier quoted context omitted.
> depending on when you put in and take out your money the returns can be negative (even in cases where you hold up to 15 years) Sorry, but unless you're talking about truly black swan circumstances like the Great Depression or the 2008 crash, I don't believe for a second that, over a 15 year timespan, holding the S&P will result in negative returns frequently enough that a typical investor has to concern themselves…
The New York Times published the same sort of analysis in 2011: http://archive.nytimes.com/www.nytimes.com/interactive/2011/... Be sure to carefully read the description of the graph. Every time I link this, someone assumes that the green & red indicates are the yearly returns, but the entire point of this graph is that it is cumulative . If it is red 20-30 years into the line, that means that money put it at the beg…
Another think to remember is that if you are saving for retirement, you are very likely doing dollar cost averaging, i.e. making deposits on a regular basis. So you aren't buying all your stocks in one year, you are buying them across a multitude of years. That greatly mitigates the risk of starting at the wrong time.
For example, I started saving for retirement in 1999. It was ugly for a while but I was positive for good as of 2009, despite all the red in that graph.