It's important to note that the principal value of the fund will fluctuate and is not guaranteed at any time, including at the stated retirement target date for the fund. (franklintempleton.com)
If you want your asset allocation adjusted automatically as you age, a good option is to invest in retirement target date funds. (moneysense.ca)
For example, target date mutual funds take the stress out of cutting risk toward retirement by naturally moving out of stocks the closer the investment gets to a set retirement target date: perhaps among the best investments now for the passive investor. (wisestockbuyer.com)