In creating this sustainable portfolio, the investor faces three paramount risks: longevity risk, inflation risk, and investment risk.

FORBES: Is Your Adviser Working as Your Chief Risk Officer (CRO)? Part I: The Importance of Managing Investment Risk

Either strategy could do more to account for longevity risk by incorporating a guaranteed product, like an annuity or longevity insurance.

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For the individual investor, longevity risk describes the risk of a person outliving the assets that can be used as financial support.

FORBES: Managing Your "Tail-End" Risk - Part 1: The Risk that You May Outlive Your Assets

So how do you know if so-called longevity risk will cause you financial problems or if your heirs may be asked to foot the bill if you run out of money?

FORBES: Managing Your "Tail-End" Risk - Part 1: The Risk that You May Outlive Your Assets

For institututional investors, longevity risk is typically defined as the risk that pension funds and life insurance companies may have to pay out more to beneficiaries than previously calculated due to rising life expectancies .

FORBES: Managing Your "Tail-End" Risk - Part 1: The Risk that You May Outlive Your Assets

We call this longevity risk.

FORBES: Managing Your "Tail-End" Risk - Part 1: The Risk that You May Outlive Your Assets

If all a wealth manager does is keep longevity and inflation risk in check for a client, the manager is covering important bases.

FORBES: Is Your Adviser Working as Your Chief Risk Officer (CRO)? Part I: The Importance of Managing Investment Risk

That said, even if an investor has longevity and inflation risk under control, an investor still faces investments that can be volatile, even over longer periods of time.

FORBES: Is Your Adviser Working as Your Chief Risk Officer (CRO)? Part I: The Importance of Managing Investment Risk

Finally, and most important, recent studies have shown convincing evidence that cardio-respiratory fitness is a much stronger predictor of longevity and reduced risk of cardiovascular mortality and all-cause mortality than BMI.

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