When I started this financial blog a couple years ago, I wondered if I would run out of ideas to blog about.  Luckily, so far anyhow, I have had a different problem — How to choose amongst all of the ideas that pop into my head.

Thing train of thought takes me to consider what explains the relative success and failure — the investing fates if you will — of various investors.  It would be foolish (and wrong) of me to make the blanket statement that smart people make poor investors.  On the contrary I believe that successful investors are very smart people — John Bogle, Warren Buffett, Carlos Slim, Peter Lynch, Bill Gross.

What is interesting and occasionally baffling to me are the poor choices that I see smart people making.  For whatever reason, people tend to share two things with me:  personal information and personal investing information.  If I had to guess why, it is for two reasons.  1) I am actually interested, fascinated in fact. 2) I am very discrete.  Still this doesn’t quite explain why relative strangers tell me these things.

One thing is for sure.  I listen. And on thing I have learned is that people love to tell of their investing success and are hesitant to share their investing misses.  I feel privileged to hear both types of stories.

For the record there is, perhaps, no such thing as a bad (or good) investment in the present.  The “goodness” or “badness” of a given investment is only truly realized when the position is closed and the gains and/or losses are counted.   There are, however, in my opinion, poor portfolio decisions.

Here is my overall impression of the types of under-performing (aka bad) portfolio decisions that smart people make.  Most notably rationalizations for extreme non-diversification.

1) I work in field X.  I understand field X.  I believe the outlook for field X is tremendous, therefore I’m going to pick my favorite stocks that participate in X.  [I heard this all the time during the tech/dot-com pre-bubble and bubble].  I’m going to focus my portfolio in X…. meaning I’m going to severely underweight all other sectors.

2) I’ve followed fund manager, fund company, or my investment manager Y, and I trust and believe in them.  I’m going to put most/all of my money in their hands.

3) I understand the economy, the markets, and what’s going on.  I’m going to make my own decisions, and cut my losses when appropriate.  I’m going to manage my own money, and I’m not going to sheepishly follow conventional wisdom (things such as time-horizon-based asset allocation and CAPM models).  I’m going to bet big and win big on what I believe in.

Over the years I’ve seen that hubris and pride are subject to positive self-reinforcement.  When bets pay off, bettors place bigger bets.  In most cases though, luck eventually runs out and large losses are realized.  This is soul searching time.  Some respond by becoming hyper-conservative for a while (I will only save money in the bank and in T-Bills), some by becoming moderate for a while (I will own some stocks, but mostly bonds), and some by doubling down.

I understand these impulses.  In fact I see that impulse control is a key factor in rational investing.  I understand that smart people are accustomed to being correct.  It is instinctual to believe that this extends to investment decisions.  I’m saying, “If you believe you are orders of magnitude smarter than ‘the market’, think twice.” Or put another way, it is better to be wise than smart when it comes to investing.

To summarized, I know first hand that smart people sometimes make very dumb portfolio decisions.  They believe that their personal academic and career success will translate directly to investment success.  I also know that many such very smart people have been burned, to the tune of $100,000+ (if not millions) of losses directly attributable to non-diversification.

And finally, as to my personal investments, I happily say that I have been relatively steadfast in my Boglehead-like investing style.  So far it has paid dividends.