From 1946 through 1997, stocks rewarded investors with a compound average annual return of 7.5% after inflation. But many economists believe investors should expect smaller returns in the future--perhaps as little as 5% after inflation. That would sharply boost the amount investors need to save for retirement, as illustrated by these examples, prepared by 401(k) adviser Financial Engines:

JACK, AGE 55, has $1.48 million in stocks and wants to retire in 10 years with $2 million in today's dollars. He wants a 75% probability of hitting that goal, and he's on track if he saves 9% of his $150,000 salary and if stocks yield 7.5% (after inflation). But if Jim believes equity returns will be lower, he'll have to save more.

------------ANNUAL SAVINGS------------- EQUITY RETURN PERCENTAGE OF SALARY TODAY'S DOLLARS

7.5% 9% $13,500 6.0 25 37,500 5.0 37 55,500

JANET, AGE 45, has $844,550 in stocks and wants to retire in 20 years with $2 million in stocks (in today's dollars). Like Jim, she wants a 75% probability of hitting that goal-which is a good bet if she saves 9% of her $150,000 salary and if stocks return 7.5% after inflation. But under a lower-return scenario, here's how much more she'll have to save:

------------ANNUAL SAVINGS------------- EQUITY RETURN PERCENTAGE OF SALARY TODAY'S DOLLARS

7.5% 9% $13,500 6.0 22 33,000 5.0 31 46,500

Data: Financial Engines

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