Are you losing sleep at night, worrying what will become of your retirement account? Trying to figure out the best way to save for a big purchase in an economy that's been shaken to the core?

After some of the nation's biggest investment banks have come close to collapsing, after the stock market sank mercilessly last week then zoomed up on Monday only to close slightly lower on Tuesday, a lot of people are asking if any investments are safe any more.

But experts say don't pull all your money out of the bank or the stock market and stuff it under your mattress.

There are still some reasonable ways to invest, even though they aren't bringing in big earnings right now. And it's especially important to set up a "rainy day fund," they say. But each has a different idea about just how big that should be.

Q Is it wise to continue to contribute to company-sponsored 401(k) retirement funds, many of which invest the funds in stock-based mutual funds?

A "If your employer is matching your contributions, you especially should be stashing money away in your 401(k). If you don't, you're literally leaving free money on the table," says Christopher Davis, fund analyst with Morningstar in Chicago. Even if there's no employer match, keep on contributing. "The key to successful investing is discipline, and investing now gives you the opportunity to buy in at lower prices. You've never heard anyone say they've decided not to buy that shirt or dress now that it's gotten cheaper. The market isn't any different."

One exception is if your company's retirement fund consists primarily or exclusively of stock in that company, don't sock all of your money into it, says Jim Seward, UW-Madison School of Business finance professor.

"You're already exposed to how that business is doing because of your employment there. The last thing you want to do is have over-exposure. Your employment and your retirement fund could disappear at the same time," as it did for Enron employees, says Seward, who's also academic director for the Nicholas Center for Applied Corporate Finance.

Q How much of a "rainy day fund" should people have, in these financial times, and what type of account or investment vehicle should they use?

A Conventional wisdom suggests an emergency fund should cover three to six months of living expenses, says Davis. "But in an environment where it might be hard to find a job, it makes more sense to be conservative and try to have (enough for) six months to a year," the Morningstar analyst says.

William Priebe, co-president of Geneva Capital Management in Milwaukee, says a year and a half worth of living expenses might be appropriate, put into certificates of deposit or money market accounts. By then, Priebe says, the nation's finances will likely be back on an even keel.

Q What other advice can you offer, at this time?

A If you can't sleep at night because of the huge market drops and your health is being affected, "sell (stocks) down to your comfort level," Priebe says. But for those who have diversified investments and are not retiring for 10 years or so, "if you can ride through this, that's probably the thing to do," he adds.

Don't panic, says Chad Thomley, senior financial consultant for Thrivent Investment Management in Madison. When times are tough and investors are nervous, those can be good opportunities to invest in stocks, he says. "In 2002, the Dow Jones industrial average was around 7,500. You look back and say, 'Oh, I should have bought more then.' "

And don't take your money out of the bank, says Morningstar's Davis. "You're getting meager rates of interest from savings accounts and money markets, but stashing your money under a mattress certainly means you don't have a prayer in keeping up with inflation," he says.