For more than a year, investors have been touting strong returns from a raging bull market. At least, until this week.

The Dow Jones Industrial Average DJIA, -0.87% fell more than 700 points Friday, fueled in part by concerns over a a possible trade war between the U.S. and China. During this latest spate of intense market volatility, many people are understandably asking: What will this do to my 401(k) plan? Should I call my broker? What will happen to my retirement funds?

Spare a thought for all those Americans who have no investments in the stock market. Why? There are, unfortunately, quite a lot of them.

Just over half (54%) of Americans own stocks, according to a 2017 Gallup report. That includes individual stocks, 401(k) plans, shares in an equity mutual fund or an IRA account. What’s more, two-thirds of Americans do not participate or have access to a 401(k) plan, according to Census Bureau researchers.

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In fact, the wealthiest Americans possess more than 80% of the aggregate value of stocks. “Despite the fact that 46% of households owned stock shares either directly or indirectly through mutual funds, trusts, or various pension accounts, the richest 10% of households accounted for 81% of the total value of these stocks, though less than its 91% share of directly owned stocks 22 and mutual funds,” Edward Wolff, professor of economics at New York University, wrote in his 2017 paper “Household Wealth Trends in the United States.”

“Housing, liquid assets, and pension assets accounted for 87% of the total assets of the middle class,” he added. “The remainder was about evenly split among nonhome real estate, business equity, and various financial securities and corporate stock. Stocks directly or indirectly owned amounted to only 10% of their total assets.”

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Now may be an even better time to start investing for millennials and older Americans who have not yet started, especially for retirement, as they will be buying when many stocks are cheaper than they were on Jan. 1, said Eric Reich, an adviser at Reich Asset Management in Marmora, N.J. For those already invested, consider increasing your contribution rates and rebalancing your account if necessary, Reich said. Then, forget about it. “If you hate looking at the statement, don’t look at the statement,” he said.

Of those who do participate in a 401(k), two-thirds were directly or indirectly invested in equities — a mix of mutual funds and other pooled investments — at the end of 2015, according to the Employee Benefit Research Institute. The rest was a mix of target date funds; these are invested mostly in equities at their inception and then gradually rebalance to favor more conservative investments as the employee approaches. More plan participants were invested in stocks at the end of 2015 than before the financial crisis in 2007, it found.

And those who have no stocks or are skittish about investing? Talk to a financial adviser about your long-term goals for retirement, said Jared Snider, senior wealth adviser at Exencial Wealth Advisors in Oklahoma City. “They will help the client to manage the worry around the markets,” he said.