Are sector and thematic funds riskier than broad index funds?

Yes, meaningfully riskier, because they concentrate your money in one slice of the market instead of spreading it. A sector fund (technology, healthcare, energy) or a thematic fund (clean energy, AI, cybersecurity) rises and falls with that single area, so a downturn there hits you hard with no offset from other industries. Thematic funds also tend to launch after a theme is already hot, charge higher fees, and can hold fewer, pricier stocks. They aren't "bad," but they're a concentrated bet, not diversification — and a broad index fund already owns these sectors in sensible proportion. A reasonable rule: keep any single sector or thematic fund to a small satellite position, well under 10% of your portfolio, around a diversified core. Check the overlap before adding one at wealthserene.com/tools/portfolio-builder.