PT - JOURNAL ARTICLE AU - Vebjørn Jokstad AU - Snorre Lindset AU - Håvard Tryland TI - Exclusion Risk for Long-Term Investors AID - 10.3905/jwm.2022.1.172 DP - 2022 Jul 31 TA - The Journal of Wealth Management PG - 49--54 VI - 25 IP - 2 4099 - https://pm-research.com/content/25/2/49.short 4100 - https://pm-research.com/content/25/2/49.full AB - Portfolios with well-diversified monthly returns can have significant long-term exclusion risk. We use 30 sector portfolios with 90 years of returns. Including 10 to 15 of these sectors in an investment portfolio is sufficient to eliminate almost all idiosyncratic risk in monthly returns. We propose a simple measure for exclusion risk for long-term investors. By compounding the monthly returns over our 90-year sample period, we show that portfolios with 10 to 15 sectors are not well diversified for long-term investors; including more sectors significantly reduces the exclusion risk.