It’s a funny thing about conventional wisdom. Once it sets in, like poured concrete, it hardens and becomes difficult to crack — and most reasonable people won’t even try. That’s not the case, though, with one of investing’s most conventional pieces of wisdom — the so-called “60-40” rule.

Broadly defined, the 60-40 rule is the advisable equities/bond mix, measured in percentiles, that investors should adopt when saving for the long haul. Taken a step further, once a long-term investor reaches age 60, then the balance should be reversed, with the 60-year-old placing 40 percent of his or her portfolio in stocks, and 60 percent in bonds.

With dynamic changes in the 60-and-over demographic, especially with longer life spans, an increased need for health care savings, low retirement savings, and with so many people retiring early, among other issues, some investment experts are taking a sledgehammer to the conventional wisdom of the 60-40 rule.

[See: 8 Small-Cap ETFs With Big-Time Potential.]

“In finance, we talk often about “rules of thumb,” but many times rules should be broken,” says Jake Loescher, financial advisor, at Savant Capital Management, in Rockford, Illinois.

The idea that a 60-year-old retiree should be investing primarily in conservative investments is an antiquated way of approaching personal finance, Loescher says. “Historically, the rule of thumb stated that an individual should take the number 100, subtract their age, which will define the amount of stocks someone should have in their portfolio. For a 60-year-old, this obviously would mean 40 percent stocks is an appropriate amount of risk.

“A better approach would be to perform a risk assessment and consider first how much risk an individual needs to take based on their personal circumstances,” Loescher says.

But under what circumstances is it advisable for a 60-year-old to get more aggressive and invest in stocks? Here are five situations where eschewing the 60-40 rule, and going heavier on stocks, is a wise idea, our experts say:

The likelihood you’ll live into your 90s or beyond. Life expectancy is much longer these days, so many healthy 60-year-olds may live another 20 to 30 years, says Sharon Marchisello, author of the financial wellness blog, “Countdown to Financial Fitness.” “Thus, in today’s low-interest environment, you still face the risk of your nest egg not keeping up with inflation over the long haul,” Marchisello says.

[See: 8 Reasons to Avoid Short Selling Stocks.]

If you don’t have enough cash for retirement. “Some retirees are put back into the workforce after retiring because they didn’t accumulate enough to sustain an expected lifestyle,” says Xavier Epps, owner of XNE Financial Advising, LLC, in the District of Columbia. After a 60-year-old and his or her broker have strategically decided how much capital in a retirement portfolio they’re willing to risk for the potential upside of continued appreciation, then it’s OK to pour more cash into stocks, Epps says. “If a small portion of the portfolio is allocated toward the risky side of investments, where the majority of the portfolio is set up to be more risk-averse, then the outcome could be positive with little negative impact,” he says.

When interest rates are low. Low interest rates means an investor increases the likelihood of losing money in bonds in a rising rate environment, says Warren A. Ward, a 70-year-old financial planner at WWA Planning & Investments in Columbus, Indiana. “That makes the capital risk seem greater than the value bonds might provide as portfolio ballast,” Ward says.” Over the past few years, we’ve begun taking more of a total-return approach, using low volatility, dividend-paying stocks to replace part of our typical bond component. Our mix is now more like 70-30 and we are continuing it into retirement for most clients.”

If you have unique estate planning needs. If you don’t depend totally on your investments for income, then your money may be providing a bequest for charity or an inheritance for children, says Ryder Taff, a financial advisor with New Perspectives. “In that case, the time horizon for the portfolio is even longer.”

For historical and reliability purposes. The stock market has outperformed all other asset classes over the last century, and a passively managed index mutual fund will outperform actively managed stock mutual funds 80 percent of the time or more, says Robert Walker, CEO of Surveys & Forecasts in South Norwalk, Connecticut. “Academic studies have shown that unless you are within three years of retirement, the average variability of stocks relative to their returns is superior to that of Treasurys and bonds,” Walker says. “Plus, staying in the stock market at age 60 still gives you at least 20 years, on average, to ride out the long-term volatility inherent in equities. Even though there will be pullbacks, you’ll have time to recover.”

As Marchisello says, be sure to maintain a balanced asset allocation, and don’t put everything in the stock market when you reach age 60. “Also, have an emergency/rainy day fund in a liquid, stable investment product like a savings account or money market,” she advises. “Put part of your investment in a mutual fund or ETF that holds bonds as well as stocks.”

[See: 7 Best Mid-Cap Stocks to Buy Now.]

Do that and there’s really no reason you can’t plow more money into stocks once you’ve blown out the candles on your 60th birthday cake. After all, you probably have many more birthday cakes to come, so you’re going to need the money.

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5 Reasons to Stay in the Stock Market in Your 60s originally appeared on usnews.com