Are Index Funds Still Diversified? Concentration Risk and a Top-Heavy Market

Learn how concentration risk can affect index funds and how 2026 catch-up contributions work.

Senior news writer Anna Helhoski and Ryan Sterling, a wealth advisor with NerdWallet Wealth Partners, break down stock market concentration risk and what it means for index fund diversification. Then, hosts Sean Pyles and Elizabeth Ayoola answer a listener’s question about 2026 catch-up contributions, including FICA wages, Roth 401(k) rules for some high earners, and other ways to boost retirement savings.

NerdWallet Wealth Partners, LLC is an affiliate of NerdWallet Inc. NerdWallet Wealth Partners is a fiduciary online financial advisor, offering low-cost, comprehensive financial advice and investment management. Learn more at https://nerdwalletwealthpartners.com/ 

Use NerdWallet’s free investment return calculator to estimate how much your money can grow. Enter your planned contributions, timeline, rate of return and compounding frequency to get started: https://www.nerdwallet.com/investing/calculators/investment-calculator 

Backdoor Roth IRA: What It Is and How to Set It Up https://www.nerdwallet.com/retirement/learn/backdoor-roth-ira 

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