Perhaps the phrase “hope springs eternal” explains why so many investors have such high hopes for the stock market.

Perhaps people are still dreaming of a time not so long ago when the market made millionaires out of regular folks who were fortunate or smart enough to pick the right stocks.

But if investors continue such irrational exuberance, they could end up with a shortfall in their retirement plans, according to John Hancock’s eighth national survey of 401(k) plan participants.

The survey found that 35 percent of respondents expect the stock market to have an average annual gain during the next 20 years of nearly 16 percent. Historically, the actual return is just about 11 percent.

When it comes to bonds, 34 percent of investors expect to have an average annual return during the next 20 years of 10 percent. The actual historical return is 5.77 percent. Thirty-two percent expect returns of 9.8 percent for money market funds during the next 20 years. Such investments traditionally have averaged just 3.81 percent.

But there was one survey result that just left me dumbfounded.

An unbelievable 40 percent of those surveyed believe that their company stock is less risky than a diversified domestic stock portfolio.

It’s not like the people who were surveyed haven’t been forewarned. Mathew Greenwald & Associates conducted the poll for John Hancock in January. By then, 90 percent of the investors said they knew about Enron Corp.

So if they knew about Enron, they surely knew about the Enron employees whose retirement accounts were wiped out because they had overloaded on their company stock. The stock collapsed last year amid a series of damaging financial disclosures.

“There seems to be this halo effect people have about their own company stock,” said survey author Wayne Gates, general director of market research and development for John Hancock. “People think what happened to the Enron employees won’t happen to them.”

What part of “don’t put all your eggs in one basket” isn’t clear? Putting all or most of your money into one stock is gambling not investing.

Gates said he continues to be disappointed by the survey results, which show that people have a lack of basic understanding about investing that could cost them a comfortable retirement.

For instance, 10 percent of respondents didn’t know they could lose money in stocks. Nearly 40 percent of those questioned didn’t know they could lose money in a bond fund.

It’s not that employees can’t manage their investments, Gates said.

It’s just not a priority for many people.

“Unless investing genuinely interests you, it’s not hard to think of things more enjoyable or more pressing than studying investment options for a 401(k) plan that you won’t need for another 20 or 30 years,” he said.

Like it or not, many of us are now responsible for investing for our retirement. Like it or not, financial literacy must be a priority.

If you are unsure about what to do or what investments are right for you, get some help. First try the administrator of your 401(k) plan for information about diversifying your portfolio. You also can hire a financial planner. The National Association of Personal Financial Advisors can help you find a fee-only planner in your area. Call (800) 366-2732 or go to www.napfa.org.

To find a certified financial planner, contact the Financial Planning Association at www.fpanet.org/plannersearch or call (800) 647-6340.