The Dow Jones Industrial Average plunged a whopping 571 points Tuesday morning, the S&P 500 fell 2 percent and the Nasdaq Composite dropped 2.5 percent, giving up their gains for the year.
If you're invested in the stock market, or are thinking about investing, you don't need to lose your cool, experts say, though you can always take some basic steps to make sure you're being smart with your money.
Here are three things not to do when the market's being volatile:
James C. Kelly, a wealth strategist at PNC Bank, tells CNBC Make It that "volatility happens" and that this could be an opportunity to re-balance your portfolio, including a mix of stocks, bonds and other securities to lessen the impact of any potential loss. Consider buying more stocks while prices are low, but don't give into the temptation to "panic-sell."
"Panic-selling is the worst thing you can do," says Joe Mallen, chief investment officer at Helios Quantitative Research. Instead, "look for opportunities to put unused cash into investments you have been considering. Consider it a time when everything is briefly on sale and buy into broad market funds or individual stocks you believe in long term."
"The best thing would be to buy more, or at the very least hold tight," Greg McBride, chief financial analyst at consumer financial company Bankrate, adds. "The worst thing to do is sell into a market decline if your long-term objectives haven't changed."
During times of volatility, investing expert and "Oracle of Omaha" Warren Buffett suggests keeping a level head. In response to market swings in 2016, he said: "Don't watch the market closely." If investors are too worried about their stocks dropping "a little bit … and think they should maybe sell them when they go up, they're not going to have very good results."
So don't try to time the markets. "It's a natural instinct to want to reduce your exposure to assets that are declining," Kelly says. But "resist the urge."
If it helps, stay away from the news.
Many investors can feel overwhelmed by market volatility. A 2017 survey by Ally Invest found only one in three millennials is investing in the stock market because they find it "scary or intimidating." And a 2018 Gallup poll found less than half of young Americans are putting their money in stocks because of the 2008 market crash.
"While your gut instinct might be to sell certain positions while the markets are going haywire," Kelly says, "try to take a deep breath before making any rash decisions."
Experts recommend starting slow, remaining calm and looking at the big picture. Buffett and investing experts Mark Cuban and Tony Robbins are a good way to do that. Index funds hold every stock in an index; offer low turnover rates, attendant fees and tax bills; and fluctuate with the market so there's no risk of picking individual stocks that underperform.
After all, young investors have one of the most "valuable characteristics of investing" on their side, Mallen says: time.
"One of the biggest regrets of adults is not investing sooner. If you have yet to invest into the market, consider this volatility a great opportunity to do so, " Mallen says.
Whatever your approach, remember to pay yourself first, says Kelly. "Save as much as you can in retirement accounts " like a 401k or Roth IRA. Also, " and make sure you have an : three months to six months of living expenses. "
"When it seems like the sky is falling," he adds, "do your best to remain calm and remember that corrections and market downturns are normal and healthy. As an investor, you never want to make decisions based on emotions, especially fear, so first and foremost, try to remain calm."
McBride agrees: The best strategy is to "maintain your long-term perspective."
Here are some more tips that can help you make the most of investing.
This story was originally published on October 11, 2018, and has been updated to reflect current stock market changes.
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Video by Andrea Kramar