Since the 1980's, hundreds of large companies have switched from traditional to cash-balance plans.

Under a cash-balance plan, he would have received only $161,623, according to the study.

"But if you just make cash-balance plans illegal, what are the plan sponsors going to do?"

In cash-balance plans, the yearly gain is based on interest rates.

Q. What does a company get out of switching to a cash-balance plan?

About one-third of the nation's largest public companies have cash-balance plans or their equivalent.

Others, including cash-balance plans, may state the promised benefit as a single value.

He is especially critical of so-called cash-balance plans, which many companies are adopting.

"Most cash-balance plans have been designed to hurt older employees," he said.

"Congress could do more to give additional protection to older workers without stopping cash-balance plans."