I honestly believe dollar cost averaging is somewhat of a crock, because it assumes that you have a slush pile of money set aside that you invest on a set schedule.<p>I just thought of a way to test my thought:<p>For instance, I ran a study on my own finances. I have a complete record of dates and amounts of every sum I&#x27;ve put into retirement. I&#x27;m able to &quot;pretend&quot; I bought the S&amp;P-500 (VFINX) on those dates (rather than the investing choices I actually made), and am able to calculate an APY from that date until today. (I do this by looking up dividend-adjusted historical prices.)<p>Given that, my all-time APY would have been 6.69%.  Meanwhile, using an S&amp;P 500 Return Calculator [1], the Annualized Inflation Adjusted Reinvested Dividend performance is 6.67%.  So, almost exactly the same - maybe dollar cost averaging isn&#x27;t a crock, but in my case, not the advantage it is usually purported to be.  And this is a 20-year period that has been reasonably strong.<p>I believe the reason this happens is that people (me included) will tend to have more money to invest when times are good (and prices are high), and less to invest when times are bad (and prices are low) - so this basically eliminates any dollar-cost-averaging advantage.  I&#x27;m just one data point so I might be an unlucky outlier, but the theory makes sense to me.<p>[1] <a href="http:&#x2F;&#x2F;dqydj.net&#x2F;sp-500-return-calculator&#x2F;" rel="nofollow">http:&#x2F;&#x2F;dqydj.net&#x2F;sp-500-return-calculator&#x2F;</a>