US bank JPMorgan recently published data highlighting that the average US retail investor's portfolio was down -44% so far this year (with the value now sitting below the level it was at the beginning of 2020 before COVID hit). While it's undoubtedly been a tough year in US markets - the S&P500 index has fallen -21% this year-to-date, while the tech-heavy NASDAQ is down -31% - the magnitude of retail investor losses are still surprising. Why have retail investors, on average done so much worse than the market? We suspect it's due to retail investors' unfortunate and costly tendency to chase investment fads.