Most investors have more, many more funds that they should-over diversified. This tends to reduce returns. Many
investors have more of the same i.e. they have funds that have very similar portfolios and hence the fund portfolio is
not well-diversified. Either there are too many large cap dominated funds or far too many mid and small cap funds. What
you require is a good, balanced mix. Finally investors don't know when to exit a fund and end up carrying it even though
the future upside potential is very low.