Retirees may be focusing on the wrong risks to their financial security.

Market declines may intensify retirees' fears that they will not have enough assets to live on.

However, it turns out that this is not the most serious financial risk they should be concerned about in retirement.

Instead, the biggest financial risk is longevity — the possibility that retirees will live longer than expected and run out of money.

Longevity and the market are only two of the five major retirement risks that individuals and couples face. The other three are health, family and policy risks.

Retirees may encounter unexpected long-term care needs and medical expenses when it comes to health care.

Policy changes are also a risk for retirees, especially given the uncertain future of Social Security.

However, any changes brought about by Congressional reform are unlikely to affect today's retirees.