Most people invest a certain amount of money each week or month into an investment plan such as a Roth IRA, or traditional IRA. This investment strategy is called dollar cost averaging (DCA). Here is a formal definition explained by Investopedia “The technique of buying a fixed dollar amount of a particular investment on a regular schedule, regardless of the share price. More shares are purchased when prices are low, and fewer shares are bought when prices are high.” This system can make you a ton of money if share prices are low when you buy and high when you retire and sell your shares. Here is a model that shows how DCA can sometimes be a negative.The best approach by far is value-cost averaging (VCA). Investment-FAQ explains it as “a strategy in which a person adjusts the amount invested, up or down, to meet a prescribed target.” You will end up killing two birds with one stone with this approach. You will balance your portfolio, buy more shares when prices are low, and buy fewer shares when prices are high.

Example:
You want to contribute $100 per month in a mutual fund.(1st month)

You contributed $100 End of month balance $70
(Share price decrease)
(2nd month) You contributed $130 End of month balance $240
(Share price increase)
(3rd month) You contributed $60 End of month balance $310
(Share price increase)
(4th month) You contributed $90 End of month balance $400
(Share price has no change)

You contributed $380 but your mutual fund balance is $400. Nicely done!

Even though value-cost averaging requires you to spend ten minutes a month looking at the performance of your stocks or mutual funds it is still more efficient approach than dollar cost averaging. Being a little more proactive can make you a lot more money. But whether you choose DCA or VCA the most important thing is that you are contributing to your nest egg. So give yourself a pat on the back and picture the mansion you will buy later on.