NEW YORK >> When fear was pumping through the stock market this summer, most retirement savers kept their cool.

So say figures from Fidelity, which could see how individual investors in general behaved by looking at its 13.5 million 401(k) and 6 million IRA accounts as stocks tumbled in New York, Shanghai and places in between during the turbulent third quarter. The Standard & Poor’s 500 index sank more than 10 percent within a week during August, driving the index to its worst quarter in four years.

Even amid the tumult, only 4.9 percent of Fidelity’s 401(k) account holders made changes to how their nest eggs were invested, such as selling stocks to move into bonds or cash. Workers also diverted more of their paychecks into their 401(k) accounts than they did a year earlier, not less: an average of 8.2 percent of their pay last quarter, up from 8 percent.

"People are starting to get the message," says Jeanne Thompson, vice president at Fidelity Investments. "During volatility, many times the best course of action is none at all."

That’s because 401(k) accounts and IRAs are for long-term savings, even for investors approaching retirement. And the power of compound interest works best when investments are given time.