The Biggest Mistake An Investor Can Make

Published in Investing on 22 February 2012

This is the worst mistake you're probably making -- and here's how to fix it.

You're probably making the worst mistake an investor can make. I know I am. And after the bull run we've been enjoying, that mistake probably got a lot worse.

The French author André Maurois once said: "Everything that is in agreement with our personal desires seems true. Everything that is not puts us into a rage."

That's the mistake. "Rage" may be far too strong a word for most of us. But you'll see plenty rage around the investment discussion forums on the web -- particularly when someone presents a sensible bear case for an individual stock.

Maurois also said: "We appreciate frankness from those who like us. Frankness from others is called insolence." And therein lies the key to overcoming this mistake.

One big mistake -- lots of names

The mistake is in deciding that an investment is great for whatever reasons, then closing oneself off to alternative viewpoints. Some call it "falling in love" with a share, whilst the behavioural economists refer to it as confirmation bias; is the tendency of people to favour information that confirms their beliefs or hypotheses.

It's closely related to other ways to lose money on shares such as anchoring, overconfidence and availability bias (the tendency to give undue weight to more prominent facts).

I'd say it's also related to what Peter Lynch describes as the greatest single fallacy of investing; the feeling of being "right" when your shares have risen.

"If I had to choose a great single fallacy of investing, it's believing that when a stock's price goes up, then you've made a good investment," says Lynch.

In short, we really want to be right -- and we really don't give fair weight to the opposing viewpoints. And if anyone but a friend presents the opposing viewpoint to us, we don't like it one bit. It's an innate part of our psychology. But it's still a mistake.

How to beat it

So how do you overcome it?

Undoubtedly the most difficult thing is to set aside one's emotions. This is easy to say but harder to do. But if we can gather facts in an impartial and objective way, and weigh them well; then it has to be a good thing for investing.

There are a few useful tactics you can use to achieve this:

  • One is to pretend you're collecting the bullish and bearish points to present to other people to let them decide for themselves in a balanced way.

  • Another is to explain to a true friend who understands a little about the market why you think as you do -- and to let him/her punch a few holes in your case.

  • A third way is to try to present only the opposite side of the case -- as would a barrister, for example, in trying to paint an opposing picture. It's surprising how often this one cools your ardour.

  • And finally -- do try the discussion boards with your reasoned analysis, but promise you'll be without "rage" whatever flak your ideas attract.

Do something

But eventually there comes a time to act. When you've done all the analysis you can, and weighed the pros and cons; then act on your information. Dither no longer. Either buy, sell, or walk away without regret whatever happens next. 

You decided what you decided in the best and most objective way you could with as much factual information at your disposal as you could muster. That's it. Que sera, sera. There's a time to act and not to look back.

If you're proven to have been right -- great. But judge your decisions on a reasonable timescale and don't be fooled into thinking you were right by virtue of macro market direction alone. 

Short-term fluctuations mean nothing. If you were wrong and are looking at the same investment again down the line -- then it's a new day. What was done, was done. So the process needs to be repeated in light of new evidence or at least a revised valuation.

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Comments

The opinions expressed here are those of the individual writers and are not representative of The Motley Fool. If you spot any comments that are unsuitable hit the flag to alert our moderators.

MrContrarian 22 Feb 2012 , 9:29am

"You are not entitled to an opinion unless you can state the arguments against your opinion better than your opponents can."

Charlie Munger

goodlifer 22 Feb 2012 , 11:29am

Thank you, MrContrarian

I seem to remember reading somewhere that a good counsel can put the case against his client better than his learned friend.

goodlifer 23 Feb 2012 , 10:36pm

Most of my numerous mistakes have been caused by good old honest-to-god greed.
Can any of your tame psychos offer any help?

Dozey1 24 Feb 2012 , 4:42pm

My worst mistakes have been due to caution; taking profits off the table and missing most/all of the subsequent rise. Then again I did bale out of British Rail (or whatever it was called at the time), RBS and Mayflower with profits, so I suppose you win some and lose some.

TamePsycho 26 Feb 2012 , 4:46pm

Thank you Mr Holding.

I am currently sat on a -90% loss on Game, due to an unexplainable love affair.

goodlifer has a point about greed... Connaught wiped out an entire year's worth of portfolio dividends because of just that.

The elegance of the article only dawned on me when I looked at how I felt about my more successful purchases, which I cannot brag about because they were based on the same foolish reasoning as my unsuccessful ones.

bernie125 26 Feb 2012 , 7:04pm

I can't get emotional about any share I hold. I held ARM for years and sold out when they got above £2.50, they are now nearly £6-00 but hindsight is something ever winner has. My biggest share now is BT who I bought at an average of 120p, my get out will be 240p or sooner if they start to drop.

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