Wall Street has a message for investors: Maybe you'll live.

For years, mutual-fund companies have pounded away at the need to save for retirement, while life and health insurers have stressed the risk of ill health, disability and an early death. But with the baby boomers rapidly approaching retirement, Wall Street's tune is changing.

Now, fund companies and insurers are focusing on boomers' need for income once they're retired -- and the big push is to get seniors to realize that their retirement could last longer than they ever imagined.

Living long. To highlight "longevity risk," Genworth Financial, of Richmond, Va., has been running a series of advertisements featuring centenarians, while ads from New York's MetLife depict Snoopy decorating a 90th birthday cake. Insurers are hoping to gin up interest in a slew of products, including immediate-fixed annuities, variable annuities with living benefits, longevity insurance and long-term-care insurance.

Mutual-fund companies are also getting in on the act. Two of the largest, Boston's Fidelity Investments and Vanguard Group, of Malvern, Pa., now sell immediate annuities, which can provide lifetime income. Both fund giants also recently tweaked their "life-cycle" funds, which are diversified portfolios geared toward particular retirement dates.

Fidelity, citing rising life expectancies, raised the stock exposure in its life-cycle funds aimed at investors closest to retirement. Meanwhile, Vanguard cranked up the stock allocation for all its Target Retirement funds, including boosting the stock holdings of its Target Retirement Income fund to 30 percent from 20 percent.

The Income fund's rejiggering "didn't materially increase the downside risk," says Catherine Gordon, head of financial-planning services at Vanguard. But if an investor is making regular withdrawals, "it raised the likelihood that the portfolio would last until someone was age 85 or 90."

The notion that we could live to a ripe old age might seem like welcome news. Yet many people clearly haven't got the message. One recent survey found that 67 percent of retirees and 61 percent of working-age people underestimated the life expectancy for folks of their age.

"There's the potential for a lot of people to spend down their savings too early in retirement," worries Steven Siegel, a research actuary at the Society of Actuaries in Schaumburg, Ill., which commissioned the survey.

Weighing the odds. Want to make sure you don't outlive your money? Here are four key things to keep in mind:

The longer you live, the longer you can expect to live. Suppose you were born in 1940. At birth, your life expectancy would have been age 70 if you're a man and 76 if you're a woman.

Since then, many folks born in 1940 have died and those early deaths aren't considered when calculating the life expectancy for those who remain. Result: If you are still alive today, you can expect to live until around age 82 if you're a man and age 85 if you're a woman.

Life expectancies are averages -- and surprisingly few of us are average. Based on the above life expectancies, you might imagine there's a good chance you will die during your 80s.

But in fact, 44 percent of today's 65-year-old men will be dead by age 80 -- and 18 percent will live to age 90 or beyond, according to Hartford Financial Services in Hartford, Conn. Similarly, 31 percent of today's 65-year-old women will die by age 80 and 29 percent will live into their 90s.

"There may be 5 percent to 10 percent of 65-year-olds who are in poor enough health that they don't have to worry about living a long time," says Ken McCullum, a senior vice president in Hartford's wealth-management group. "But the other 90 percent or 95 percent could live a very long time. There's a lot of uncertainty for those folks."

If you are married, one of you will likely live longer than average. While most 65-year-old men will die before age 85 and only half of 65-year-old women will live to that age, there's a 68 percent chance that at least one member of a couple will live until age 85 and a 42 percent chance that one of them will survive to age 90.

Your odds of beating the averages may be higher than you think. The numbers above are based on the general U.S. population.

But if you're reasonably affluent and you've taken decent care of your health, you're likely to live longer. Indeed, insurers figure they are dealing with wealthier, healthier people -- and assume their clients will live maybe two years longer than the general population.

What to do? Confronted with the chance that you or your spouse will live a surprisingly long time, you might buy an income annuity, and you should probably keep your annual portfolio withdrawal rate to 5 percent or below. But your smartest move may have nothing to do with Wall Street.

"If you're really worried about outliving your savings, the best thing you can do is to delay starting Social Security," argues Henry Hebeler, who runs www.analyzenow.com, a Web site devoted to retirement issues.

Let's say you are age 62. Instead of taking Social Security today, you could put off benefits until as late as age 70 -- thus locking up a lifetime stream of inflation-linked income that's 76 percent larger.