To some extent, holding two or more similarly managed funds holding like but not identical stocks (i.e. large cap Canadian) could be considered simply as an exercise in diversification, but it doesn't take long before portfolio dilution (or "di-worsification") kicks in. This is where the portfolio risks becoming more index-like but with active management fees. That will doom any portfolio to long-term underperformance.

The industry's bloated line-up of products is to blame. If we look at the entire fund industry as one gigantic portfolio, Canadians are holding hundreds and hundreds of unique funds just to invest in Canadian stocks. I would never recommend that any investor spread money among hundreds of funds -- particularly in such a small asset class. And I have opined in the past that at least 90% of funds are probably not worthy of investors' dollars. Accordingly, investors in aggregate are bound to underperform.

Diversification is a critical component of sound portfolio construction. Investors must strike the delicate balance of having sufficient diversification (to reduce reliance on any one stock) with the need to stay focused enough to make active management worth paying for. Dilution (or excessive diversification) can result in an expensive, index-like portfolio. Too focused a portfolio can incur too much risk (making success more uncertain)."