I intended on writing this at some point, but Dr. Wesley Gray (an acquaintance of mine, and whom I respect) beat me to the punch.  As he said in his blog post at The Wall Street Journal’s The Experts blog:

WESLEY GRAY: Imagine the following theoretical investment opportunity: Investors can invest in a fund that will beat the market by 5% a year over the next 10 years. Of course, there is the catch: The path to outperformance will involve a five-year stretch of poor relative performance.“No problem,” you might think—buy and hold and ignore the short-term noise.

Easier said than done.

Consider Ken Heebner, who ran the CGM Focus Fund (CGMFX), a diversified mutual fund that gained 18% annually, and was Morningstar Inc.’s highest performer of the decade ending in 2009. The CGM Focus fund, in many respects, resembled the theoretical opportunity outlined above. But the story didn’t end there: The average investor in the fund lost 11% annually over the period.

What happened? The massive divergence in the fund’s performance and what the typical fund investor actually earned can be explained by the “behavioral return gap.”

The behavioral return gap works as follows: During periods of strong fund performance, investors pile in, but when fund performance is at its worst, short-sighted investors redeem in droves. Thus, despite a fund’s sound long-term process, the “dollar-weighted” returns, or returns actually achieved by investors in the fund, lag substantially.

In other words, fund managers can deliver a great long-term strategy, but investors can still lose.

That’s why I wanted to write this post.  Ken Heebner is a really bright guy, and has the strength of his convictions, but his investors don’t in general have similar strength of convictions.  As such, his investors buy high and sell low with his funds.  The graph at the left is from the CGM Focus Fund, as far back as I could get the data at the SEC’s EDGAR database.  The fund goes all the way back to late 1997, and had a tremendous start for which I can’t find the cash flow data.