Loss Aversion And Sunk Cost Fallacy
Every investor likes making profits, but very few enjoy experiencing losses. In fact, according to Behavioral Finance, the emotional pain of losing money is often far stronger than the happiness of earning the same amount. Losing ₹10,000 hurts much more than gaining ₹10,000 feels rewarding. This natural tendency influences almost every financial decision we make, often without us realizing it.
In this chapter, Parag Parikh explores two of the most powerful psychological biases that affect investors: Loss Aversion and the Sunk Cost Fallacy. These biases are responsible for countless poor investment decisions, from holding onto losing stocks for years to refusing to admit mistakes even when all evidence suggests that moving on would be the wiser choice.
The chapter opens with one of Warren Buffett's most famous investment principles:
"Be fearful when others are greedy, and greedy when others are fearful."
While the advice sounds simple, the author immediately asks an important question: Is it really that easy?
Anyone who has witnessed a major market crash knows the answer. During periods such as the COVID-19 market collapse, stock prices fell rapidly across the world. News channels predicted economic disaster, investors panicked, and fear spread faster than facts. Under such circumstances, buying quality companies becomes emotionally difficult even though history has repeatedly shown that these periods often present the best long-term opportunities.
The reason is simple: human beings are not naturally wired to remain calm during uncertainty. Our brains are designed to avoid danger, and financial losses trigger that same survival instinct. Instead of making rational decisions, we become driven by emotion.
Parag Parikh explains that this emotional behavior appears in several different forms. Throughout the coming chapters, he discusses four major behavioral biases that frequently influence investors:
Loss Aversion, the fear of suffering losses.
Sunk Cost Fallacy, the inability to ignore money or effort that has already been spent.
Status Quo Bias, which leads to decision paralysis.
Endowment Bias, where investors become emotionally attached to assets they already own.
This chapter focuses on the first two.
The discussion begins with Loss Aversion, perhaps the most influential behavioral bias in investing.
To demonstrate how it works, the author presents a simple thought experiment.
Imagine someone offers you ₹1,000 along with two choices.
The first option guarantees a profit of ₹500.
The second option involves flipping a coin. If the coin lands on heads, you receive ₹1,000. If it lands on tails, you receive nothing.
Mathematically, both choices have the same expected value. Yet most people prefer accepting the guaranteed ₹500 instead of taking the risk.
Now consider another situation.
This time, instead of gaining money, you must choose between two ways of losing it.
The first option guarantees a loss of ₹500.
The second option again depends on a coin toss. Heads means you lose nothing, while tails means losing the full ₹1,000.
Surprisingly, most people now choose the risky option.
The mathematics remain identical in both situations, but the emotional response changes completely.
When faced with potential gains, people become conservative.
When faced with certain losses, they suddenly become gamblers.
This is the essence of Loss Aversion.
People dislike realizing losses so much that they often take greater risks simply to avoid admitting defeat.
Parag Parikh explains that this subconscious tendency affects nearly every aspect of investing.
Many individuals prefer fixed-income investments over equities, not because fixed-income products necessarily generate higher returns, but because they appear psychologically safer.
Investors often sell profitable stocks too early because they fear those profits might disappear. At the same time, they continue holding loss-making stocks for years, hoping prices will eventually recover.
Ironically, this behavior creates portfolios filled with weak companies while the strongest businesses are sold prematurely.
The author makes an interesting observation that people are not necessarily risk-averse. Instead, they are loss-averse.
If avoiding losses requires taking greater risks, many investors willingly do so.
Another example appears in taxation.
People naturally dislike paying taxes because taxes represent money leaving their hands. This emotional resistance sometimes causes individuals to reject profitable opportunities simply because they dislike the idea of paying tax on their gains.
Parag Parikh advises readers to think differently.
Rather than focusing on the tax itself, investors should concentrate on the income generated after taxes. Paying tax generally means profits have been earned, making it a sign of success rather than failure.
The author illustrates loss aversion through a practical portfolio example.
Suppose an investor owns two stocks.
One investment in Wipro has doubled from ₹25,000 to ₹50,000.
Another investment in TCS has declined from ₹1,00,000 to ₹50,000.
Now imagine the investor urgently needs ₹50,000.
Most people would immediately sell Wipro because it has generated profits while refusing to sell TCS because doing so would permanently lock in a loss.
However, Parag Parikh argues that this reaction is driven entirely by emotion rather than logic.
Instead, he recommends selling portions of both investments.
This approach reduces tax liabilities, maintains diversification, and avoids allowing emotions to dictate investment decisions.
The second major bias discussed in this chapter is the Sunk Cost Fallacy.
Unlike loss aversion, which focuses on avoiding losses, the sunk cost fallacy arises when people continue investing time, money, or effort simply because they have already invested so much in the past.
The author explains this through an everyday example.
Imagine enrolling in an expensive course.
Halfway through, you realize that the subject no longer interests you and offers little value for your future career.
Many people nevertheless continue attending classes because they believe quitting would waste the money already spent.
From an economic perspective, this reasoning is flawed.
The money has already been spent regardless of future decisions.
Continuing simply to justify previous expenses only wastes additional time and energy.
The same mistake frequently occurs in financial markets.
Investors often continue purchasing more shares of declining companies simply because they want to reduce their average purchase price.
Instead of asking whether the business remains attractive today, they become obsessed with recovering past losses.
Money that has already been invested should never influence current investment decisions.
The only question that matters is whether the company deserves new investment based on its present and future prospects.
If the answer is no, previous losses should not justify committing additional capital.
Parag Parikh offers several practical methods for overcoming these psychological traps.
The first recommendation is to assume that your ability to tolerate losses is actually lower than you believe. This mindset naturally encourages more careful decision-making before investments are made.
The second recommendation is diversification.
By spreading investments across different asset classes and companies, investors reduce the likelihood that any single mistake will significantly damage their financial future.
Diversification cannot eliminate risk entirely, but it can greatly reduce emotional pressure during periods of market volatility.
Another valuable suggestion is to focus on the portfolio as a whole rather than constantly monitoring individual stocks.
A diversified portfolio rarely experiences the same dramatic fluctuations as individual securities. Viewing investments collectively helps reduce unnecessary anxiety and encourages more rational thinking.
The author also encourages investors to let the past remain in the past.
Whenever tempted to average down on a falling stock, ask yourself a simple question:
"If I did not already own this stock today, would I still buy it at its current price?"
If the answer is no, purchasing additional shares merely because of previous losses makes little sense.
Finally, Parag Parikh introduces an interesting psychological insight based on Weber's Law.
When realizing losses, investors should generally accept them all at once rather than spreading them across multiple painful decisions.
Conversely, profits can often be booked gradually over time.
This approach aligns more closely with how human beings naturally process gains and losses.
The chapter concludes by emphasizing that successful investing requires more than understanding businesses—it requires understanding ourselves. Loss aversion and the sunk cost fallacy are deeply rooted psychological tendencies that affect nearly everyone. However, investors who recognize these biases can gradually reduce their influence by relying on discipline, diversification, and rational decision-making instead of emotional reactions.
By mastering these behavioral challenges, investors become better equipped to navigate market uncertainty and make decisions based on future opportunities rather than past mistakes. This prepares readers for the next chapter, where Parag Parikh explores two more powerful behavioral biases: Decision Paralysis and the Endowment Effect, both of which silently influence countless investment decisions every day.