Trading Psychology Key indicators for Understanding

Trading Biases

Mind Games

There is a story that circulated widely amongst Indian stock market participants a few years ago, and it remains one of the most striking illustrations of what long-term equity investment can produce when human psychology is removed from the equation entirely.

A caller rang into a financial television programme seeking help with a practical administrative matter. His grandfather had purchased shares in a well-known Indian tyre manufacturing company decades earlier, back in the early 1990s, and those shares still existed in physical certificate form stored away at home. The caller wanted to know how to convert them into digital, or DEMAT, format.

The programme host walked the caller through the conversion process and then, almost as an aside, mentioned what those shares would be worth at current market prices.

The stock was trading at approximately 64,000 rupees per share. The grandfather held 20,000 shares.

20,000 multiplied by 64,000 rupees = 1,28,00,00,000 rupees, or approximately 128 crore rupees.

One hundred and twenty-eight crore rupees, sitting in a dusty envelope in an attic.

The reaction of anyone hearing this story for the first time is almost always the same. Shock, followed immediately by a cascade of questions. How did the grandfather have the foresight to invest in this company all those years ago? What kept him committed through the decades that followed? How did he resist the temptation to sell when the gains became significant, as they surely did long before they reached 128 crore rupees?

The Uncomfortable Answer

Here is what a closer examination of the story actually reveals.

The grandfather did not demonstrate extraordinary discipline or visionary foresight. He did not resist the temptation to sell through gritted teeth whilst watching his investment multiply. He simply forgot about the shares. They sat in the attic, unexamined and unconsidered, whilst the company grew and the share price followed. He was not paying attention to daily price movements. He had no stock broker calling him with updates. He was not monitoring the portfolio or reacting to market news.

He forgot. And that forgetting made him extraordinarily wealthy.

Now consider the alternative scenario. Suppose the grandfather had stayed closely connected to his investment. Suppose a friend or a broker had been keeping him informed of the share price on a regular basis. At some point, the stock would have doubled from his purchase price. Would he have sold? Most investors would have. At a 100 per cent gain, the temptation to lock in profits is almost universal.

If not at 100 per cent, then perhaps at 200 per cent. Or 500 per cent. Somewhere along the journey from the original purchase price to 64,000 rupees per share, a psychologically alert and actively engaged investor would almost certainly have found a reason to exit the position. The news cycle would have provided justification. A market correction would have created fear. A rival company’s strong results would have cast doubt. The stock price passing through a round number would have felt like a natural exit point.

The typical investor who sells at 100 or 200 per cent gains is not making a poor decision by conventional standards. Those are excellent returns by any measure. But they are a small fraction of what patience and inattention delivered in this case.

What This Story Actually Teaches

The grandfather’s story is not an argument for buying shares and ignoring them indefinitely. It is an illustration of something more specific and more important: that human psychology, when actively engaged with an investment, introduces a set of powerful forces that work systematically against long-term wealth creation.

These forces are called biases. They are not character flaws or signs of poor intelligence. They are patterns of thinking that are deeply embedded in human cognition, shaped by evolutionary pressures that had nothing to do with financial markets. In most areas of life, these mental patterns serve people reasonably well. In the stock market, they frequently lead to decisions that feel rational in the moment but prove costly over time.

Consider what might have happened had the grandfather been actively monitoring his MRF holding. Every time he looked at the price, he would have been doing so through the filter of his own biases. If the stock had recently risen, he might have felt the urge to sell before the gains disappeared, a bias known as loss aversion operating in reverse. If the stock had recently fallen, he might have anchored to the higher price he had recently seen and felt reluctant to buy more, a pattern known as anchoring bias. If friends or colleagues were selling their stocks during a market downturn, he might have felt compelled to follow, an expression of the bandwagon effect. If a financial newspaper published a bearish view on the tyre sector, he might have found himself focusing on that opinion whilst discounting the positive signals, a tendency known as confirmation bias.

None of these reactions would have felt irrational at the time. Each would have felt like a reasonable response to available information. Yet collectively, they would have steered him away from one of the greatest investment outcomes in Indian market history.

Why Biases Matter for Every Market Participant

The grandfather’s story is an extreme and exceptional case. Most investments do not produce 2,000 per cent returns over decades. But the psychological forces at work in his story operate at every level of market participation, in every trade, every investment decision, and every portfolio review that any participant undertakes.

A trader making ten decisions a day in the stock market is subject to these biases ten times a day, often without being aware of it. An investor reviewing their portfolio once a quarter still encounters them at every review. The biases do not announce themselves. They operate silently, shaping the framing of decisions, the interpretation of information, and the emotional response to outcomes in ways that feel entirely natural and justified.

The profit and loss statement of any market participant is, to a significant degree, a record of how successfully they have managed these biases. Technical skill, access to information, and quality of analysis all contribute to outcomes. But the psychological dimension, the ability to recognise and counteract the distortions that biases introduce, is equally important and considerably harder to develop.

This chapter and the ones that follow are dedicated to identifying the most common and consequential biases that affect traders and investors in financial markets. For each bias, the goal is not simply to name it but to understand the mechanism behind it, recognise how it manifests in real trading and investment decisions, and develop practical awareness that reduces its influence over time.

The biases covered in the chapters ahead include anchoring bias, recency bias, confirmation bias, the bandwagon effect, loss aversion, the illusion of control, and hindsight bias. Each of these has been studied extensively in the field of behavioural finance, and each leaves a measurable imprint on the decisions of market participants who are unaware of its influence.

Understanding these patterns is one of the most valuable investments any participant in the stock market can make in their own development as a trader or investor.