Given the market mayhem of the past couple of weeks, you would expect that financial planners have been juggling calls at all hours from worried clients. But Matthew Edelstein, who handles almost 200 clients, says his phone has hardly rung. The reason: The vast majority of his clients have bought annuity contracts, which promise guaranteed payments during retirement, in good times and bad. "I have no horror stories," says the Grayslake, Ill., adviser.

After three years of falling sales, the $220 billion annuity business is expected to get a boost from the recent market turmoil, analysts say. The Hartford Financial Services Group (HIG) is rolling out a campaign this week based on the recent volatility. Some insurers saw jumps even before they had time to prepare new promotions: Sales of New York Life Insurance Co.'s flagship fixed immediate annuity are up 62% this month from the same time a year ago. "The dicier the markets get, the stronger our story becomes," says Chris Blunt, an executive vice president at New York Life.

Annuities are investment contracts that a customer buys and later receives payments from over several years. Fixed annuities guarantee a particular rate, while variable annuities are a tax-advantaged form of investing in the stock market; for a fee, investors can receive guaranteed lifetime payments even if the market goes down. In June, the Government Accountability Office, the investigative arm of Congress, suggested that some investors could benefit from buying annuities from insurance companies that guarantee income rather than trying to manage their money themselves.

Sales for annuities, a staple of many insurance companies, were already rising this year up more than 16% to $60 billion in the first quarter of 2011, according to Limra, an industry-backed research group. "If you want to continue market exposure, yet you need to have certain level of income, now would be an appropriate time to put assets in an income annuity," says Drew Denning, vice president of retiree services at Principal Financial Group (PFG) .

But the guarantee comes at a price. The contracts can be complex, making them hard to compare, says Barbara Roper, director of investor protection for the Consumer Federation of America. Annuities also can carry high commissions and impose charges if you have to cash out early. Meanwhile, many fixed annuities are suffering from the same problems as other guaranteed income products: They don't offer much income. Many fixed annuities now are offering annual returns of 3% to 4%, and those rates could drop if interest rates on bonds fall, says Jeremy Alexander, CEO of Beacon Research, which tracks annuity sales.

Annuities can help some investors sleep at night in times of uncertainty but they are hardly a one-size-fits-all solution.