Leo Acheson: Investors looking for a set-it-and-forget-it option where they can literally invest their entire portfolio should consider Vanguard's Target-Date Retirement Series. The series offers a fund for investors of all different ages. An investor would select a portfolio based on the date that they expect to retire. So, for instance, if you are 50 years old, the 2035 fund would be appropriate because at that point you'd be 65.
The reason why the set-it and forget-it approach is so attractive is that it derisks over time for you automatically so you don’t have to worry about that. So for younger investors, it holds about 90% stocks, and then over time it gradually derisks to about 30% by age 72, where the equity weighting plateaus.