Home Trading psychology Common Behavioral Mistakes in Trading

Common Behavioral Mistakes in Trading

No matter how good strategies you have, they are most likely worthless if you can’t execute them properly due to behavioral mistakes in trading. What looks like a piece of cake in a backtest, is completely different in the real world when you are risking your own hard-earned money.

To avoid behavioral mistakes in trading is more important than the strategy. If you can’t minimize behavioral mistakes, you will deviate from what the strategy tells you to do.

This article contains two examples of behavioral mistakes and how they influence profits. One is taken from a book and one is from my own trading career.

Will the strategy continue to perform after a drawdown? Is it just a temporary setback?

The future is always uncertain and it’s pretty common to give up a good strategy after a setback or drawdown. How likely is it that you are going to do what the strategy tells you to do?

Behavioral mistakes are an important “cost” to consider in both investing and short-term trading. We all fall prey to our cognitive biases, be it in relationships, decision making, or in your daily job.

The Art Of Thinking Clearly

We all fall prey to cognitive errors and behavioral mistakes. When money is at stake these tendencies magnify, and we tend to do more of them. What exactly are cognitive errors (or behavioral mistakes)? I copy the definition by the Swiss author Rolf Dobelli in The Art of Thinking Clearly:

The failure to think clearly, or what experts call a “cognitive error”, is a systematic deviation from logic – from optimal, rational, reasonable thought and behaviour. By “systematic” I mean that these are not just occasional errors in judgement, but rather routine mistakes, barriers to logic we stumble over time and again, repeating patterns through generations and through the centuries. For example, it is much more common that we overestimate our knowledge than that we underestimate it. Similarly, the danger of losing something stimulates us much more than the prospect of making a similar gain. In the presence of other people we tend to adjust our behaviour to theirs, not the opposite. Anecdotes make us overlook the statistical distribution (base rate) behind it, not the other way around.

The book by Dobelli reads well and summarizes much of the research by Kahneman and Tversky into a shorter and more enjoyable read.

What are some of the major behavioral trading biases?

The list of trading biases is almost endless. We have previously written about some of the most obvious in addition to the two mentioned below in this article.

Decision making is part of our daily lives and I consider reading a cheap investment for learning and understanding more about yourself:

If you know yourself, you understand the markets

If you know yourself very well, I would say you should better understand markets and thus make more money trading or investing. Mark Douglas writes in Disciplined Trader (page 56):

“Understanding yourself is synonymous with understanding the markets because as a trader you are part of the collective force that moves prices. How could you begin to understand the dynamics of group behaviour well enough to extract money from the group, as a result of their behaviour, if you don’t understand the inner forces that affect your own?”

How to lose money in the best performing fund

Below is a pretty interesting excerpt that has been circulating in social media for some years (I found it in Quantitative Value by Wesley Gray and Tobias Carlisle). In the decade ending in 2010, the majority of the investors in the best performing fund managed to lose money!

In the decade to December 31, 2009, the Wall Street Journal reported that the best-performed U.S. diversified stock mutual fund according to fund-tracker Morningstar was Ken Heebner’s CGM Focus Fund. Over the decade, the fund had gained 18.2 percent annually, beating its closest rival by 3.4 percent per year, which is exceptional. The typical investor in Heebner’s fund, however, lost 11 percent annually. Investor returns, also known as “dollar-weighted returns,” take into account the capital flowing into and out of the fund as investors buy and sell. The investor returns were lower than the fund’s total returns because investors bought into the fund after it had a strong run and then sold as it hit bottom. Heebner’s fund surged 80 percent in 2007, and then investors poured in $2.6 billion. The following year, the fund sunk 48 percent, and investors yanked out more than $750 million. Said Heebner: “A huge amount of money came in right when the performance of the fund was at a peak. I don’t know what to say about that. We don’t have any control over what investors do.” This behavior caused the investor returns in Heebner’s fund to be among the worst of any fund tracked by Morningstar. Amazingly, this means that the worst investor returns were found in the decade’s best-performed fund. We are each our own worst enemy.”

My own big behavioral trading mistake

I can’t remember my best trades as there is not much to learn from them. I rather focus on trying to avoid ruin and huge mistakes. To illustrate how difficult trading is, I want to finish this short article by writing about my biggest mistake during my day trading career:

I clearly remember two days in August 2007 where I completely screwed up. It was a Thursday and all my day trading strategies performed badly, ending my day with my biggest financial loss ever. I probably react twice as bad to a loss as a react positively on an equal gain, like most people, and thus this loss made me feel pretty bad. I have loss aversion.

The next day was the third Friday of the month where options expire. Historically this has been the best day of the month (for my strategies) but I was so shaken by the loss the day before so I scaled down all my strategies as much as I could. Needless to say, Friday was a field day and would have generated 2x times the loss from the day before if I had traded my normal size (I managed to recoup just 20% of my losses).

Even with very good strategies, it’s possible to end up losing because of wrong position sizing behavioral mistakes!


– How does the uncertainty of the future impact the success of a trading strategy?

The article suggests that it’s common for traders to abandon a strategy after a drawdown or setback. It questions how likely traders are to stick with a strategy through uncertain times.

– What are cognitive errors or behavioral mistakes, and why are they important in trading?

Cognitive errors are systematic deviations from logical, rational thought and behavior. The article highlights their significance, especially in trading, when emotions and biases come into play.

– Why is understanding oneself considered essential in trading or investing?

The article quotes Mark Douglas, emphasizing that understanding oneself is crucial because traders are part of the collective force that moves prices. Self-awareness is vital for successful trading.