Herding Bias in Trading: Why Traders Follow the Crowd

Herding bias in trading showing traders following the crowd

Have you ever seen a stock suddenly become popular and felt that you should buy it because everyone else seems to be buying? Maybe the price is rising, social media is full of positive posts, and people around you are talking about the same trade. The pressure to join the crowd can become surprisingly strong.

This behaviour is commonly described as herding. In financial markets, herding occurs when investors or traders make decisions that are influenced by the actions or decisions of other market participants. It can appear during powerful rallies, sharp sell-offs, popular trades, or periods of uncertainty.

But following the crowd is not always as simple as being irrational. Sometimes other people's actions contain useful information, while in other situations traders may simply copy the crowd because of FOMO, social pressure, or uncertainty. Research also suggests that herding can vary across markets, time periods, sectors, and market conditions.

In this article, we will examine what herding bias means in trading, why traders follow the crowd, how researchers identify herding, and what research says about Indian markets. We will also separate herding from FOMO, momentum trading, and confirmation bias, before looking at practical ways traders can make more independent decisions.

What Is Herding Bias in Trading?

Herding bias in trading refers to the tendency to follow the actions or direction of other market participants instead of making a decision independently. A trader may notice that many people are buying a stock, selling a particular asset, or discussing the same trade and then decide to act in the same direction.

The important point is that herding is about similar behaviour among market participants. It does not necessarily mean that every person has exactly the same reason for making a trade. Some may have analyzed the company's fundamentals, while others may simply be following what they see the crowd doing.

What Herding Means in Trading

Imagine a stock starts moving sharply higher. More traders notice the price increase, see positive discussions online, and begin buying. As more people participate, the move attracts even more attention. A trader who enters mainly because other traders are already buying is displaying behaviour consistent with herding.

The same pattern can occur on the way down. During a sharp sell-off, seeing other participants exit their positions can create pressure to sell as well, even when the trader has not independently reassessed the underlying investment or trading thesis.

Why Following the Crowd Can Feel Safe

Following other traders can feel reassuring because it reduces the discomfort of making a decision alone. If many people appear to agree with a trade, an individual may feel that the decision is less likely to be wrong. In uncertain markets, observing other participants can also appear to provide information that the individual trader does not have.

That is why herding should not automatically be described as irrational. Copying others can sometimes be a reasonable response when their actions provide useful information. The problem arises when a trader follows the crowd without understanding why the crowd is acting that way or without checking whether the decision fits their own risk and trading plan.

Why Do Traders Follow the Crowd?

Traders do not always follow the crowd because they believe the crowd is right. Sometimes the behaviour comes from uncertainty, social pressure, or the feeling that other market participants may know something they do not. The same outward behaviour can therefore have very different psychological causes.

Social Proof

When many people appear to make the same decision, that behaviour can act as social proof. A trader may interpret widespread buying as evidence that the trade is attractive, even without independently checking the underlying reasons behind the move.

Fear of Missing Out

FOMO can make a trader feel that waiting is more dangerous than entering. A rapidly rising stock, a popular trade on social media, or repeated discussions about an opportunity can create urgency. The trader may then buy because other people are already participating rather than because their own analysis supports the entry.

Uncertainty and Information Gaps

Financial markets contain incomplete information. When a trader is uncertain, observing the actions of other participants can seem useful. If those participants are believed to possess better information, following them may appear reasonable rather than purely emotional.

Fear of Being Wrong Alone

Making an independent decision can be uncomfortable when everyone around you appears to disagree. If a trader buys while the crowd is selling, a wrong decision can feel especially difficult because there is no group to share the responsibility with. Following the majority can therefore provide psychological comfort even when the decision has not been independently evaluated.

Reputation and Social Pressure

Social influence can also affect people whose decisions are visible to others. Fund managers, analysts, or traders may sometimes consider how their decisions will look relative to their peers. In such situations, matching the behaviour of others can be influenced by reputational concerns rather than simply by expectations about price.

These factors can overlap. For example, uncertainty may make a trader look to others for information, while FOMO and social proof can make the same trader act quickly. Understanding the specific trigger behind the decision is therefore more useful than simply labeling every crowd-following action as irrational herding.

Is Herding Always Irrational?

Following other market participants is not automatically irrational. In some situations, traders may observe the actions of others because those actions contain information they do not have. In other situations, however, people may copy the crowd simply because they feel safer doing what everyone else is doing.

Rational Herding

Rational herding can occur when an investor reasonably believes that other participants have useful information. For example, if several well-informed investors independently react to new information, observing their actions may provide a trader with an additional signal.

This does not mean the crowd is always correct. It means that imitation can sometimes be a logical response to information asymmetry rather than a purely emotional decision.

Irrational Herding

Irrational herding is more closely associated with social influence, emotional pressure, or simple imitation. A trader may buy an asset because it is trending everywhere, because friends are making money from it, or because social-media discussions create a fear of being left behind.

In this situation, the trader may have little independent evidence supporting the decision. The behaviour is being driven primarily by what other people are doing.

Information Cascades

An information cascade provides a useful way to understand how crowd behaviour can develop. Imagine that traders make decisions one after another. Early traders act on their own information, while later traders can observe those decisions. If later traders believe the earlier actions contain valuable information, they may choose to follow them even when their own private signals point in another direction.

Once enough people follow the same path, the visible actions of the crowd can become a powerful signal in themselves. This can create a chain of similar decisions without requiring every participant to have independently reached the same conclusion.

Reputational Herding

Herding can also have a professional or institutional dimension. A fund manager, for example, may consider what other managers are doing because deviating significantly from the consensus can create reputational risk if the decision performs poorly.

Therefore, the important question is not simply “Did the trader follow the crowd?” but “Why did the trader follow the crowd?” The answer can help distinguish an information-based decision from behaviour driven mainly by social or emotional pressure.

What Does Research Actually Show About Herding?

Research on herding is more complicated than simply asking whether investors move in the same direction. Researchers need to determine whether unusually similar trading behaviour is actually evidence of herding or whether it can be explained by common information, market movements, or other factors.

How Researchers Detect Herding

One common approach in academic research is to examine how individual asset returns move relative to the overall market. Measures such as Cross-Sectional Absolute Deviation (CSAD) and Cross-Sectional Standard Deviation (CSSD) are used to study whether the dispersion of individual returns behaves differently from what would normally be expected when market movements become stronger.

If individual returns begin moving unusually closely together as the overall market movement becomes larger, researchers may interpret that non-linear relationship as evidence consistent with herding.

For readers who want to explore the research behind herding in financial markets, see the IMF review of herd behavior in financial markets by Sushil Bikhchandani and Sunil Sharma.

Why the Method Matters

There is an important limitation: a finding of low return dispersion does not automatically prove that investors are copying one another. Similar returns can also result from common information, broad market news, industry-wide developments, or other market-wide forces.

This is why researchers consider the sample period, market conditions, sectors, and market-cap groups when interpreting herding results. Two studies can examine different periods or segments of the same market and reach different conclusions without either result necessarily being meaningless.

Herding Is Not a Constant Market Condition

Research suggests that herding can vary with the direction and intensity of the market. Evidence across markets has reported differences between rising and falling periods, while some studies also find differences between smaller and larger companies or between particular sectors.

This makes it risky to describe herding as a permanent characteristic of a market. A better question is whether the evidence indicates herding under particular conditions and during particular periods.

Why Research Findings Can Disagree

Differences in data periods, asset groups, market regimes, methodology, and the way herding is defined can affect the results. A study covering a calm market may produce different evidence from one covering a financial crisis or an unusually volatile period.

For that reason, the strongest interpretation is not simply “herding exists” or “herding does not exist.” The more useful question is when, where, and under what conditions does herding appear?

Does Herding Happen in Indian Stock Markets?

The evidence from Indian financial markets does not give us a simple yes-or-no answer. Different studies covering different periods, market conditions, and groups of securities have reached different conclusions. That makes the Indian market a particularly useful example of why herding should be studied as a conditional phenomenon rather than treated as a permanent market characteristic.

Evidence Before 2020

Several studies using Nifty and NSE data from periods before 2020 reported no significant evidence of herding. Some of this research also examined different market conditions, including rising markets, falling markets, and periods of extreme price movements, without finding a consistent herding pattern.

These findings suggest that simply observing investors moving in the same direction is not enough to establish herding. Common market information or broad movements in asset prices can produce similar-looking behaviour without investors necessarily copying one another.

What Changed During the COVID-19 Period?

Evidence from the COVID-19 period presents a different picture. Research covering Indian markets during March to December 2020 reported evidence of herding, while the same research found no comparable evidence during the 2011–2019 period.

This contrast is important because the COVID-19 period brought an unusual combination of uncertainty, extreme volatility, rapidly changing information, and strong market reactions. It suggests that market conditions can influence whether herding becomes more visible.

Evidence From More Recent Nifty 500 Research

More recent research covering the Nifty 500 over 2013–2024 has also reported evidence of herding, particularly during declining markets. The study incorporates India VIX and examines the relationship between market conditions and herding behaviour.

At the same time, the findings do not mean that every market variable automatically causes herding. The research reported that trading volume and market volatility did not Granger-cause herding, highlighting the importance of distinguishing correlation, market conditions, and causal claims.

Evidence of Anti-Herding

Indian research becomes even more interesting at the sector level. Some NSE-based analysis has found evidence of anti-herding in certain settings, particularly when daily returns are examined. In such cases, investors appear to move more independently rather than converging toward the same behaviour.

So, does herding happen in the Indian stock market? The most defensible answer is: sometimes, under certain conditions, and not consistently across every period or market segment. The conflicting evidence is not a weakness to hide; it is an important part of understanding how market behaviour actually works.

Does Herding Change in Bull and Bear Markets?

Herding does not necessarily appear with the same intensity in every market environment. Research across different markets suggests that the tendency can change depending on whether prices are rising or falling, how uncertain investors are, and which types of securities are being examined.

Herding During Bull Markets

During a strong bull market, rising prices can attract increasing attention from investors. Seeing more participants buying can reinforce the belief that the trend will continue. Research has also reported stronger buy-side herding in some bull-market settings, particularly among smaller companies.

However, a rising market by itself does not prove herding. Investors may independently respond to the same positive information, which can create similar trading behaviour without investors actually copying one another.

Herding During Bear Markets

Falling markets can create a different form of pressure. When prices decline sharply, investors may pay closer attention to what other participants are doing and become more willing to sell after observing widespread selling.

Some research finds herding to be more pronounced during declining markets, while other evidence suggests that sell-side herding can become particularly relevant among larger companies during bear-market periods.

Small-Cap vs Large-Cap Stocks

Market capitalization can also matter. Smaller companies may attract stronger buy-side herding during optimistic periods, while larger companies can show stronger sell-side herding during periods of market stress. These findings show why conclusions about “the market” can hide important differences between groups of securities.

Why Crisis Periods Deserve Special Attention

Periods of extreme uncertainty can change investor behaviour quickly. The COVID-19 period in India is one example where research reported evidence of herding that was not present in the earlier period examined by the same line of research.

This does not mean every crisis automatically creates herding. It means unusual market conditions can provide an environment in which crowd-driven behaviour becomes more visible or more strongly detected.

The broader lesson is simple: herding should be considered conditional, not constant. The market direction, security characteristics, information environment, and period being studied can all influence what researchers observe.

How researchers detect herding behavior in financial markets

Herding vs FOMO vs Momentum Trading vs Confirmation Bias

Herding can look similar to several other trading behaviours, especially when a trader enters a popular trade or follows a strong market move. However, these concepts describe different things. Understanding the distinction can help you identify what is actually influencing your decision.

Behaviour What It Mainly Means
Herding Following the actions or direction of other market participants
FOMO Fear-driven urgency to avoid missing a perceived opportunity
Momentum Trading A strategy that seeks to benefit from continuing price trends
Confirmation Bias Giving greater weight to information that supports an existing belief

Herding vs FOMO

Herding describes a behaviour in which a trader's decision is influenced by what other market participants are doing. FOMO is the emotional fear of missing an opportunity. The two can occur together: a trader may see everyone buying a rising stock, feel afraid of missing the move, and then buy mainly because of that crowd activity.

Herding vs Momentum Trading

Momentum trading and herding can produce similar-looking trades, but the reasoning can be completely different. A momentum trader may deliberately follow a defined strategy based on price trends and predetermined rules. A trader displaying herding behaviour may enter simply because other people are buying. A momentum strategy can therefore be systematic without being an example of psychological crowd-following.

Herding vs Confirmation Bias

Confirmation bias affects how a trader processes information, while herding primarily concerns the influence of other people's actions. For example, a trader may already believe that a stock will rise and then selectively pay attention to bullish opinions. That is confirmation bias in trading. If the same trader buys mainly because many other traders are buying, herding may also be involved.

Herding vs Anchoring Bias

Anchoring bias in trading involves giving too much importance to an initial reference point, such as an earlier price or expectation. Herding is different because the key influence comes from the observed behaviour of other market participants. A trader can experience both, but one does not automatically imply the other.

Why These Differences Matter

Identifying the underlying behaviour can make a trading review more useful. If the main problem is FOMO, a cooling-off period may help. If the problem is confirmation bias, deliberately looking for evidence against the trade may be more useful. If the problem is herding, the trader needs to examine whether the decision still makes sense without relying on the crowd's behaviour.

How Herding Appears in Real Trading

Herding becomes easier to recognize when you look at everyday trading situations. A trader does not necessarily need to copy one specific person. The crowd can influence a decision through social media, popular market narratives, rapidly rising prices, or the visible actions of many other traders.

WhatsApp or Telegram Tip-Driven Buying

Imagine a trader receives a message saying that a particular stock is about to rise and sees several people in the same group discussing the opportunity. Without independently checking the company's fundamentals, technical setup, or risk, the trader buys simply because everyone appears convinced.

The important clue is not the messaging platform itself. It is the reason for the decision: “Other people are buying, so I should buy too.”

Social-Media-Driven Small-Cap Rallies

A small-cap stock begins attracting attention on social media after a sharp price increase. More posts appear as the price rises, which attracts additional traders. A trader who enters mainly because the stock has become popular may be responding to the crowd rather than independently evaluating the opportunity.

Popularity alone, however, does not prove herding. Traders can independently reach the same conclusion after studying the same information. The underlying decision process matters.

IPO Listing-Day Rushes

An IPO can attract intense attention around its listing. If early buyers push the price higher and other traders immediately join because they see the move happening, the resulting buying pressure can resemble herding. A trader may be reacting to the visible actions of others rather than evaluating whether the current price makes sense for their own strategy.

Options-Chain FOMO

Suppose a trader notices unusually high attention around a particular call option and sees other traders discussing the same strike price. The trader enters because the crowd appears confident that the underlying asset will continue moving in that direction.

This can combine herding and FOMO: the crowd provides the social signal, while fear of missing the move creates the urgency to act. The two concepts are related, but they are not identical.

“Everyone Is Buying” Situations

The simplest example is also one of the easiest to miss. A trader may hear friends discussing a stock, see it trending online, notice strong buying activity, and conclude that joining the trade is safer than staying out.

Before entering, a useful question is: “If I had not seen what other traders were doing, would I still take this trade based on my own analysis?”

If the answer is no, the crowd may be influencing the decision more than the trader realizes.

Why Can Herding Become Dangerous?

Following other traders is not automatically harmful, but it can become risky when the crowd replaces independent decision-making. The danger is not simply that many people are making the same trade. It is that a trader may enter, increase, or exit a position without understanding the reasons behind the crowd's behaviour.

Independent Analysis Can Take a Back Seat

When a trade becomes popular, a trader may stop asking whether the opportunity fits their own strategy. The fact that many other people are participating can become the main reason for the decision. This makes it harder to evaluate the trade objectively.

Entering After a Large Move

A strong price move can attract attention and create the impression that the trend must continue. Traders who join only after seeing others profit may enter at a very different risk point from those who entered earlier. If the original crowd enthusiasm fades, the late entrant may be left with a difficult decision.

Risk Assessment Can Become Weaker

Crowd confidence can make a trade appear safer than it actually is. A trader may focus on how many people support the idea rather than considering position size, potential downside, or what would invalidate the trade.

Exits Can Become Crowd-Driven Too

Herding is not limited to buying. The same influence can appear during a sell-off. A trader may exit because everyone around them is selling, even when they have not independently reviewed the reasons for the decline or considered whether the position still fits their plan.

Volatility Can Amplify the Behaviour

Periods of uncertainty and rapid price movement can make crowd signals feel more important. A trader who is already unsure may pay greater attention to what others are doing, which can create a cycle in which visible market behaviour influences more decisions.

Still, it is important not to conclude that herding always causes losses or that every coordinated market move is dangerous. Investors can independently respond to the same information, and following informed participants can sometimes be rational. The real risk arises when crowd behaviour becomes a substitute for independent reasoning and risk management.

How Can Traders Reduce Herd-Driven Decisions?

The goal is not to stop paying attention to what other market participants are doing. Market activity can contain useful information. The aim is to prevent crowd behaviour from becoming the main reason for a trade. A few simple decision rules can create a pause between seeing the crowd and acting on it.

Define Your Entry Rules Before Checking Market Sentiment

Before looking at social-media discussions, popular trades, or other crowd signals, decide what conditions must be present for you to enter a trade. This makes it easier to judge the opportunity on its own merits instead of allowing the crowd to define the setup for you.

Set Your Position Size in Advance

Decide how much capital you are willing to risk before checking how confident other traders appear to be. A popular trade should not automatically receive a larger position simply because many people are supporting it.

Ask “Why Am I Taking This Trade?”

Write down the specific reason for entering before placing the order. If the answer is mainly “everyone is buying,” “people online are saying it will rise,” or “I don't want to miss the move,” pause and reassess the trade.

Use a Cooling-Off Period After a Hot Tip

A short delay can help separate an emotional reaction from a considered decision. When a trade suddenly becomes popular, give yourself a predefined amount of time to review the setup before executing. The purpose is not to predict whether the crowd is right or wrong, but to prevent urgency from making the decision for you.

Keep a Trading Journal

Record what triggered each trade, what information supported it, and whether other people's actions influenced your decision. After enough trades, patterns can become easier to see. You may discover that certain social-media trends, chat groups, or rapid price moves repeatedly trigger impulsive entries.

Review the Decision Without the Crowd

After entering a trade, ask yourself whether you would still have taken the position if you had never seen the crowd's opinion. This simple counterfactual question can reveal how much influence other participants had on the decision.

Build an Independent Decision Process

A structured process does not require ignoring the market or refusing to learn from other traders. Instead, it gives you a framework for evaluating outside information. Use other people's actions as one possible signal, then check whether the trade fits your own analysis, risk limits, and predefined conditions.

The objective is not to become completely independent of market information. It is to make sure that “everyone else is doing it” is never the entire investment thesis.

Trader's framework to avoid herd-driven decisions

Common Trading Mistakes Caused by Herding

Herd-driven decisions can appear in different forms. Sometimes the mistake is obvious, such as buying only because a stock is trending everywhere. In other cases, the influence is subtle and only becomes clear when a trader reviews several decisions together.

Buying Because Everyone Else Is Buying

A trader may enter a position mainly because other traders are already participating. The popularity of the trade becomes the reason for entering, while the trader's own analysis remains secondary.

Entering After a Large Price Move

A rapidly rising stock can create the impression that the opportunity is becoming more attractive simply because the price is moving quickly. Entering late because other traders appear to be making money can expose a trader to a different risk profile from the original participants.

Copying Tips Without Understanding the Thesis

A trade idea shared through social media or a messaging group can be useful as a starting point for further research. The mistake occurs when the trader copies the position without understanding why the trade was suggested, what could invalidate it, or how much risk is involved.

Increasing Position Size Because of Crowd Confidence

Seeing strong agreement from other traders can create a false sense of certainty. A trader may increase position size because the crowd appears confident, even though the underlying evidence has not become stronger for their own strategy.

Ignoring Contradictory Evidence

Once a trader joins a popular trade, information that challenges the crowd's view can become uncomfortable to consider. This can make it harder to reassess the position objectively when market conditions change.

Exiting Only When the Crowd Starts Selling

Herding can influence exits as well as entries. A trader who waits for everyone else to start selling may react only after a large move has already occurred. An independent exit rule can help prevent the crowd from becoming the trigger for the decision.

The common thread in these mistakes is not simply that other people influenced the trader. It is that the crowd became more important than the trader's own decision process. Recognizing that difference is the first step toward making more deliberate decisions.

Key Takeaways

  • Herding bias in trading occurs when a trader's decision is influenced by the actions or direction of other market participants.
  • Following the crowd is not automatically irrational. Other traders' actions can sometimes contain useful information, while emotional imitation can create irrational herding.
  • FOMO, momentum trading, and confirmation bias are not the same as herding. They can interact with herding, but each describes a different behaviour or mechanism.
  • Academic research uses methods such as CSAD and CSSD to investigate whether market returns show patterns consistent with herding, but low return dispersion alone does not prove that investors are copying one another.
  • Evidence from Indian markets is mixed and time-dependent. Some studies found little or no significant herding before 2020, while research has reported herding during the COVID-19 period and in more recent market data.
  • Herding can vary across bull and bear markets, market-cap groups, sectors, and periods of uncertainty. It should therefore not be treated as a constant market characteristic.
  • Specific decision rules—such as setting entry conditions and position size before checking crowd sentiment, using a cooling-off period, and recording the reason for each trade—can help reduce herd-driven decisions.
  • The goal is not to ignore the crowd completely. The goal is to ensure that other people's actions are not the entire reason for your trade.

Frequently Asked Questions

What is herding bias in trading?

Herding bias in trading is the tendency to make trading decisions based on the actions or direction of other market participants rather than relying mainly on independent analysis. It can occur when traders buy or sell because many others appear to be doing the same thing.

Why do traders follow the crowd?

Traders may follow the crowd because of social proof, FOMO, uncertainty, information gaps, fear of being wrong alone, or social and reputational pressure. In some situations, observing other traders can also provide useful information.

Is herding always irrational?

No. Herding can sometimes be rational when an investor reasonably believes that other participants possess useful information. Irrational herding can occur when traders mainly copy others because of social pressure, emotion, or the fear of missing an opportunity.

What is an information cascade in trading?

An information cascade occurs when people make decisions sequentially and later participants place increasing weight on the actions of earlier participants, sometimes even when their own private information suggests something different. This can create similar decisions across a group.

Is herding the same as FOMO?

No. Herding describes behaviour influenced by what other market participants are doing, while FOMO describes the fear of missing a perceived opportunity. They can occur together, but they are different concepts.

Is momentum trading the same as herding?

No. Momentum trading can be a deliberate, rules-based strategy that seeks to benefit from continuing price trends. Herding occurs when the actions or direction of other participants become an important influence on the trader's decision. A momentum trade can therefore be systematic without being psychological herding.

Does herding happen in the Indian stock market?

Research on Indian markets gives a mixed answer. Some studies found no significant evidence of herding during earlier periods, while research has reported herding during the COVID-19 period and in more recent Nifty 500 data. The evidence therefore depends on the period, market conditions, and securities being studied.

Does herding increase during market crashes?

Some research has found stronger herding during declining or stressful market conditions, but this is not a universal rule. Herding can vary across market regimes, market-cap groups, sectors, and periods of uncertainty.

How can traders avoid herd mentality?

Traders can reduce herd-driven decisions by defining entry conditions and position size in advance, using a cooling-off period after a hot tip, recording the reason for each trade, and checking whether the trade still makes sense without relying on the crowd's opinion.

How do researchers measure herding?

Researchers commonly use measures such as Cross-Sectional Absolute Deviation (CSAD) and Cross-Sectional Standard Deviation (CSSD) to investigate whether individual asset returns move together in ways that may be consistent with herding. However, these measures do not automatically prove that investors are copying one another, so the research context and methodology matter.

Conclusion

Herding is one of the more interesting behaviours in financial markets because following other people is not automatically a mistake. Sometimes the actions of other market participants can provide useful information. The problem begins when the crowd becomes the main reason for a trading decision and independent analysis is pushed aside.

Research also shows why there is no simple answer to whether herding always exists. Evidence can change across time periods, market conditions, sectors, and groups of securities. The Indian market provides a good example, with different studies reporting different results across different periods and conditions.

For individual traders, the practical lesson is not to ignore the crowd completely. Instead, use market sentiment as information while keeping your own entry rules, risk limits, and decision process intact. Before following a popular trade, ask yourself whether you would still take the same decision if you had never seen what everyone else was doing.

The crowd can provide a signal, but it should not become your entire reason for taking a trade.

Disclaimer

This article is for educational and informational purposes only. It does not constitute financial, investment, trading, or tax advice. Trading and investing involve risk, and losses can occur. Always conduct your own research and consider your financial situation and risk tolerance before making any financial or investment decision.

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