The U.S. stock market sell-off ushered in the New Year with such a scare that a record 6 million investors called Fidelity Investments asking what they should do with their money.

Retirement accounts at Fidelity ended 2015 lower than a year ago, with average 401(k) balances dropping to $87,900 from $91,300, the Boston-based brokerage firm’s latest analysis showed Thursday.

For the two-thirds of workers who have at least some savings in target-date funds, geared toward a future retirement date, the lower balances raised doubts.

Target-date mutual funds are managed by professional advisers who adjust the mix of stocks, bonds and cash equivalents based on the selected time frame.

But it can be hard to fight the urge to do something in the face of economic uncertainty.

“They’re worried about what’s going on with China, what’s going on with the election,” said Jonathan Kelley, an adviser in Lakewood, Colo.

Kelley’s job is to talk his clients out of making emotional decisions. He typically creates a mix of investments for them, sometimes with target-date funds and a custom mix that operates like a target-date fund, and sticks with it.

Most investors do the same. More than 99 percent of Vanguard account holders do not make any trades. In the depths of the last recession, only 6 percent of Fidelity investors made changes.

If leaving everything to the target-date fund manager makes you too anxious, you may customize allocations for additional fees. Jeanne Thompson, a vice president at Fidelity, said more employers are offering managed account options within 401(k) plans. Private financial advisers also can do this, as can automated online account management services, like Betterment.com.

Rather than dump target-date funds altogether, an investor could adjust a portfolio simply by choosing a more appropriate fund. Check online to see how your fund stacks up against other options in terms of return and expenses.

Millennials could be in target-date funds that underestimate how long they will work.

If a 30-year-old selects a target-date fund set for 2042, that may be unnecessarily conservative, leaving him or her without enough income to retire then.

Right now, the stock-bond mix in a 2042 target-date fund would probably be similar to one set for 10 years later, Thompson said, but investors would need to review their options as they get older.

 

Beth Pinsker writes for Reuters.