FYI: The practice of diversification is justly popular, not only because it reduces portfolio risk but also because, at least for equity investors, it improves the odds of landing a winner. Most stocks disappoint. Equity funds thrive not because they hold many stocks that perform well, but instead because their relatively few successes outweigh their more-numerous failures. After all, a stock can only lose 100% of its value, but it can gain a great deal more.
Regards,
Ted
https://www.morningstar.com/articles/937522/the-drawback-of-diversification