This is the ‘biggest mistake’ you can make during bear markets, says investigative strategist

In the days since the start of the US-Iran war, the stock market has followed a common pattern: an initial selloff on the news, followed by more volatility and a slow recovery.

“The US equity selloff appears to have reversed in the short term, which makes sense,” Scott Helfstein, chief investment strategist at investment firm Global X, wrote in a note earlier this week. “Political events often lead to short periods of volatility, but markets are usually quick to recover losses and move higher in the following weeks.”

Indeed, since 1979, the S&P 500 has risen by 2.2%, on average, in the month following wars, geopolitical events and energy crises, according to data from the Stock Trader’s Almanac.

In times of market volatility and geographic uncertainty, it can be tempting to get your money out of the market. After all, even if the market makes a long-term comeback, scary headlines can drive stock prices down quickly. Investors don’t have to think back too far to remember when the slate of new US tariffs led to a 19% decline in the stock market in 2025.

But a financial planner often advises on making any major changes to your long-term plans based on current events.

“Staying invested in areas of political, economic and market disruption is important,” Helfstein tells CNBC Make It. “The biggest mistake a taxpayer can make is to go out of the market, which increases the risk of missing a leap or a new innovation.”

Well, you might be thinking, but what if I get a bad feeling about the market and can sell before the stock prices drop?

The answer is, you can protect your portfolio from big losses, but that is only half the battle. Because then you have to figure out when to go back inside. And because the stock market is always going up, you’re putting yourself in mathematical danger if you keep your money sitting on the sidelines, experts say.

Consider research from the Hartford Funds company, which found that an investor who broadcasts in the S&P 500 would have ended up with about $224,000 if they had invested $10,000 in 1995 and held until 2024. If, during the same holding period, the same investor missed 10 days by $3500, 4% to $5. Missing the best 30 days leaves the investor with $38,000.

In order not to think that the key is to avoid investing when stocks are falling, 50% of the best days of the market over the example occurred during bear markets (periods of decline of 20% or more), Hartford Funds were found, and 28% occurred during the first two months of the bull – before they realized more money than the uptick takes forever.

Now, would a real trader ever sell all their stock one day before buying it again the next? Maybe not. But the data shows a simple point: To take advantage of a market that often goes up, investors can’t win by keeping their money out of stocks.

So what should be done when things don’t seem right? Ideally, you add to your long-term, diversified portfolio when prices drop, says Ryan Detrick, chief market strategist with the Carson Group.

“The stock market is the only place where things are sold, people leave the shop shouting,” he says. For those who plan to hold for the long term, continuing to invest when prices fall means you’re buying stocks at a lower price, he adds.

“If you have this plan ahead of time, you probably know that these are the strongest companies that I can get at the cheapest price right now,” he says.

It’s easier said than done when you see big red numbers on your portfolio page and scary headlines on your screen – that’s why some pros recommend doing your best to invest blindly.

“Put yourself in a position to be listening as little as possible all the time,” says Christine Benz, director of financial and retirement planning at Morningstar. “Put all those gifts on autopilot.”

Once you have an established asset mix – this will vary depending on your investment goals and the duration of your goal – you can let safe money flow into your accounts without worrying about how the next geopolitical or economic event will affect your portfolio, he says.

“Yes, the stock market is a good place to put some money to work if you can,” says Benz. “But I think you can set yourself up for success by setting a target level of safety, getting into some sort of resource allocation … and then you can adjust.”

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