When a Winning Stock Gets Too Big
November 10, 2026
“How one good investment can quietly change your portfolio”
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Suppose you bought a stock when it made up 5% of your portfolio. It did well, and now it accounts for 20%. You haven’t bought another share, but one company now accounts for a fifth of what you have invested. That’s a bigger bet than the one you made when you first bought it.
According to the Financial Industry Regulatory Authority (FINRA), concentration risk can build when one investment outperforms the rest of your portfolio. Here’s what that looks like in dollars and cents. If that stock falls 25% when it makes up 20% of your portfolio, the stock alone takes 5% off the value of the entire portfolio, assuming everything else holds steady.
The Takeaway: The next time you review your investments, look at how much of your portfolio your biggest winner represents today. If you were starting from scratch, would you put that much into one company?
Please keep in mind this information should not be considered as financial advice. Investment decisions should be based on individual research and consultation with a qualified financial professional. The value of investments can fluctuate, and past performance is not indicative of future results. Always consider your risk tolerance and financial goals before making investment decisions.
