What it is
Concentration risk is the danger that arises from having a disproportionately large portion of an investment portfolio invested in a single security, industry, or geographic area. If that concentrated holding or sector performs poorly, the entire portfolio can suffer substantial losses, outweighing gains from other, smaller positions. This risk is opposite to diversification, which aims to spread investments across many different assets to mitigate specific risks.
Retail investors often face concentration risk through owning a large amount of their employer's stock, or by heavily investing in a few "magnificent seven" type growth stocks. While concentrated bets can lead to outsized gains if successful, they also expose the investor to severe downside if those specific investments falter. Financial advisors typically recommend diversification to manage this risk, ensuring no single investment can devastate a portfolio.
Why it matters
Concentration risk can lead to significant losses if your few large holdings underperform. Diversifying your portfolio is key to managing this risk.
Reviewed under editorial standardsUpdated September 26, 2026Not investment advice