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Emotional impulses to sell during downturns or buy into certain categories when they're peaking (think meme stocks, crypto or gold) make sense when considering human evolution, experts said.
"We're wired to actually run with the herd," Klontz said. "Our approach to investing is actually psychologically the absolute wrong way to invest, but we're wired to do it that way."
Market moves can also trigger a fight-or-flight response, said Barry Ritholtz, the chairman and chief investment officer of Ritholtz Wealth Management.
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"We evolved to survive and adapt on the savanna, and our intuition ... wants us to make an immediate emotional response," Ritholtz said. "That immediate response never has a good outcome in the financial markets."
These behavioral mistakes can add up to major losses, experts say.
Consider a $10,000 investment in the S&P 500 from 2005 through 2024.
A buy-and-hold investor would have had almost $72,000 at the end of those 20 years, for a 10.4% average annual return, according to J.P. Morgan Asset Management. Meanwhile, missing the 10 best days in the market during that period would have more than halved the total, to $33,000, it found. So, by missing the best 20 days, an investor would have just $20,000.