Choosing the Safest Investment Path for a Comfortable Retirement

When you're young, you can't be too aggressive when buying mutual funds that invest in stocks.

But by the time you reach an older age and your paycheck stops, you need reliable sources of income to pay your bills. This transition from aggressive to conservative investing starts around age 50.

How do you navigate this turn in middle age? That's the trickiest question in personal finance.

To begin, you need to figure out how much money you'll need each year when you retire. In one pot, put essential expenses, such as food, housing, clothing, auto, utilities, medical and taxes. That's your floor. In the other pot, put your lifestyle expenses — hobbies, gifts, entertainment and travel.

Option 1: Safety 1

Planners have two broad ways of funding these two parts of your retirement. Some take a safety-first approach, as outlined by economist Zvi Bodie, coauthor of Risk Less and Prosper. He advises you to cover all your essential expenses with guaranteed sources of money, including Social Security, a pension, lifetime-payout annuities, I-bonds (inflation-adjusted U.S. savings bonds), short-term bond funds and certificates of deposit. If you're married, your safe investments should cover you and your spouse.

If your safe investments won't produce enough income to cover your "floor" expenses, the answer is to rethink and reduce your expenses, Bodie says. You can't afford to gamble on stocks for growth. You might lose capital or run out of money. If you hold enough safe investments to more than cover your essential bills, however, you can afford to risk some money in stocks or stock mutual funds, to cover lifestyle expenses. This part of your budget can rise or fall, depending on how the market performs.

Option 2: Total Return Investing

The second and more traditional approach — known as "total return investing" — uses the famous 4 percent rule. You own a portfolio of diversified stock and bond funds, with roughly half in stocks. At retirement, you withdraw 4 percent of your assets in the first year, and raise that amount each year by the inflation rate.

At today's low bond-interest rates, however, 4 percent is too high, says William Bernstein, a portfolio manager and author of The Ages of the Investor. A 65-year-old should probably take just 3 percent, to protect his principal, he says. Or you could start with 4 percent and skip inflation adjustments when the market is poor.

Option 3: Mixing It Up