Familiarity Bias: Why Every Indian Portfolio Has the Same 10 Stocks

Open your Zerodha holdings page right now.

Count your top 10 positions.

How many of them are household names you could recognise without looking at the ticker? Reliance. TCS. Infosys. HDFC Bank. ITC. Bajaj Finance. SBI. L&T. Hindustan Unilever. Asian Paints.

If the answer is seven or more, your portfolio looks exactly like the portfolio of 50 lakh other Indian retail investors. You did not copy them. They did not copy you. The overlap is not a coincidence. It is the result of a cognitive pattern that behavioural finance has documented for forty years, and it has a specific name. Familiarity bias.

The feeling that a company is safe because you know the name is not analysis. It is a mental shortcut. And in the last five years, that shortcut has cost Indian retail investors more than they realise.

What Is Familiarity Bias, and Why Is Every Indian Portfolio Built on It?

Familiarity bias is the tendency to favour investments you recognise from daily life over investments you would have to research. It is not about loyalty, patriotism, or emotional attachment. It is about mental ease. The brain rates a familiar option as less risky than an unfamiliar option, even when the underlying financial characteristics are identical or worse.

The bias was first documented in detail by researchers studying retirement plan allocations in the United States in the 1990s. Workers at Coca-Cola held an overwhelmingly high percentage of their 401(k) in Coca-Cola stock. Workers at Enron held an overwhelmingly high percentage in Enron. The pattern repeated across every company studied: employees held the stock of the company they worked for at rates far above what portfolio theory would justify. They rated it as safer. It was not. Enron proved that.

In India, the bias shows up one step removed. Most retail investors do not hold the stock of their employer in large concentration. Instead, they hold the stock of companies whose products they use every day. You pay your HDFC Bank home loan. You order on Amazon using your ICICI credit card. You drink Parle-G. You drive a Maruti. You watch a Samsung television. You brush with a Colgate toothpaste. You use Reliance Jio. You wash clothes with Surf Excel. Every product you touch creates a mental shortcut: I know this company, therefore I understand this company, therefore this company is a safe investment.

The logic collapses under one question. Do you know how this company made its quarterly numbers last year? If the answer is no, you do not understand the company. You recognise the brand. Those are different things. Recognition is a memory function. Understanding is an analytical function. Familiarity bias tricks your brain into treating them as the same thing.

Why Does Your Portfolio Look Identical to Everyone Else's?

There are roughly 5,000 listed companies in India across the NSE and BSE. The Nifty 50 covers 50 of them. The Nifty 100 covers 100. Yet if you audit 50 lakh Indian retail demat accounts, the top 10 most-held stocks account for a wildly disproportionate share of aggregate holdings. The top 20 account for more. By the time you reach the top 50, you have captured the holdings of the vast majority of retail investors.

Why does this concentration exist? Three forces stack on top of each other.

The advertising filter. Indian television and print media run advertisements for roughly the same 100 companies. These are the companies with large marketing budgets, which are generally the same large-cap companies that dominate the indices. If you grew up watching Indian television, your brain has been trained for 20 years to recognise Reliance, Tata, Hindustan Unilever, ITC, and Bajaj. When you opened a demat account and looked for stocks to buy, your first mental query was "what companies do I know?" The advertising filter had already pre-selected your answer.

The IPO pipeline. When a company goes public in India, the retail quota gets filled first by investors who recognise the brand. Zomato, Paytm, Nykaa, and LIC each saw massive retail participation not because retail investors read the red herring prospectus, but because they recognised the name. The same bias that drives secondary market holdings also drives primary market allocations. The result is that retail IPO investors cluster in the same tiny set of consumer-facing companies while ignoring the hundreds of B2B companies, specialty chemicals makers, capital goods manufacturers, and regional players that actually compound capital.

The peer effect. When your colleague, brother-in-law, or WhatsApp group talks about stocks, they talk about the same 10 stocks. You cannot discuss a stock you have never heard of with people who have also never heard of it. Conversation naturally clusters around the names everyone already knows. Over time, this conversational clustering reinforces the familiarity filter. You hold what your social circle holds. Your social circle holds what you hold. The portfolio is not a product of independent analysis. It is a product of social convention dressed up as conviction.

If you still doubt that Indian retail portfolios cluster, look at the research. A 2025 study in Advances in Consumer Research examining cognitive biases among Indian retail investors found that familiarity bias and heuristic-driven selection were among the most prevalent patterns, significantly shaping which stocks investors chose to hold. The researchers noted that retail investors rely heavily on recognition, social signals, and online forums rather than fundamental analysis, creating systematic clustering in the same names. (This pattern is closely related to home bias, where 100% of your portfolio is in India.)

How Much Has Familiarity Bias Actually Cost You?

This is the uncomfortable part. The argument for holding familiar names has always been that "blue chips are safe" and "blue chips compound slowly but reliably." Look at the last five years of actual data and the argument falls apart for some of the most familiar names in Indian retail portfolios.

Between April 2021 and April 2026, the Nifty 50 index gained approximately 50% on a price basis. Over the same five-year window, HDFC Bank delivered roughly flat returns, and Infosys declined by about 6%, as documented by market analysis covering the 2021 to 2026 period. Two of the most widely held stocks in Indian retail portfolios underperformed the benchmark by 50 to 56 percentage points over half a decade. That is not a minor deviation. That is a structural failure of the familiarity filter.

Think about what those numbers mean in rupees. If you put ₹5 lakh into HDFC Bank in April 2021 because it felt safe, you would have roughly ₹5 lakh today. The same ₹5 lakh in a Nifty 50 index fund would be worth around ₹7.5 lakh. The difference is ₹2.5 lakh of return you did not earn. If you put the same ₹5 lakh into Infosys, you would have roughly ₹4.7 lakh, a loss, while the Nifty was up 50%. These are not hypothetical numbers. These are the actual opportunity costs of holding familiar names instead of the index.

The counter-argument is that these are just two stocks, cherry-picked in hindsight. That misses the point. Familiarity bias does not fail on every stock every time. It fails on a few specific stocks at unpredictable intervals. The problem is that if you concentrate 60% of your portfolio in 10 household names, you only need two or three of them to underperform for 5 to 10 years and your entire portfolio underperforms the benchmark. You took on concentration risk without being compensated for it. The market did not owe you a return just because the company ran nice advertisements.

What Are the Three Fingerprints of Familiarity Bias in Your Holdings?

Diagnosing the bias is more useful than listing its consequences. Here are three specific patterns you can look for in your Zerodha or Groww account right now.

Open your holdings, sort by value, and write down the top 10. For each one, answer honestly: do I hold this because I researched the company, or because I recognised the name? If more than six are pure name-recognition plays, you are running a familiarity portfolio. This does not automatically mean the portfolio is bad. It means you did not earn the concentration. The concentration chose you, and you signed off on it because the names felt comfortable.

This is a harder question. Run through your entire holdings list, not just the top 10. Count how many companies you own whose products, services, or customers you have never directly interacted with. If the number is less than five out of your total holdings, you are filtering the investable universe by familiarity. You are excluding roughly 4,950 listed Indian companies because you do not use their products. That is not a research filter. That is a recognition filter masquerading as research.

Run your SIP lineup through a holdings overlap check. If you own three large-cap funds plus a portfolio of direct stocks, the funds probably already hold most of your direct stocks in their top 10. You have duplicated the exposure, paid expense ratios on the duplicated portion, and still believe you are diversified. Your SIPs are probably more concentrated than you think precisely because familiarity bias operates inside fund managers' minds too. Large-cap funds tend to cluster in the same 25 to 30 names that make up the Nifty 100. If your direct picks are Nifty 100 names and your mutual funds are Nifty 100 funds, your real diversification is far lower than your number of positions suggests.

How Does PortoAI Detect Familiarity Bias in Your Actual Data?

Self-diagnosis is hard because familiarity bias is invisible from the inside. Every position looks justified when you review it alone. The bias only becomes visible when you compare your portfolio to a benchmark or to the aggregate retail portfolio. That is exactly what PortoAI does.

When you connect your Zerodha or Groww account to PortoAI using the read-only API connection that never exposes your password, the behavioural fingerprint system runs three checks that surface familiarity bias directly.

Concentration score against the aggregate retail portfolio. PortoAI compares your top holdings against the composition of a typical Indian retail portfolio. If your overlap is above 70%, you are told explicitly that you are holding what everyone else holds. This is not a judgment. It is a data point. Some investors want to be contrarian and are shocked to learn they are actually following the herd. Others are fine with it and just want confirmation. Either way, you get the number.

Sector concentration detection. Familiarity bias does not just cluster in specific names. It clusters in specific sectors. Indian retail portfolios are overweight banks, IT services, and consumer goods because those are the sectors with the most recognisable brands. PortoAI flags when your sector weights deviate significantly from the Nifty 500 benchmark, so you can see at a glance that you own 40% banks and 25% IT when the market is 25% banks and 13% IT. The sector tilt tells you where your familiarity filter is strongest.

SIP overlap analysis. For every mutual fund in your portfolio, PortoAI pulls the top 10 holdings and calculates how much of your SIP money is actually flowing to distinct companies. If three of your funds each hold 8% in HDFC Bank, your effective HDFC Bank exposure through funds alone might be 7 to 8% of your total SIP. Add your direct holding and the real exposure could be 12 to 15%. Few retail investors know their true concentration because they have never added up the exposure across funds and direct holdings together.

These three outputs make familiarity bias concrete. You do not have to guess whether you have it. You see the numbers. The same way PortoAI spots overtrading in your Zerodha history by looking at trade frequency and size, it spots familiarity bias by looking at what you own and how closely it matches the herd.

What Should You Actually Do About It This Week?

Familiarity bias is not fixed by panic-selling your blue chips and buying stocks you have never heard of. That is a different bias (overcorrection). The fix has three steps, in order.

Step 1: Measure. Before you change anything, know where you stand. Run your portfolio through an overlap check. Write down your sector concentration. Calculate the percentage of your top 10 that are pure name-recognition holdings. These three numbers are your baseline. Without a baseline, any action you take is guesswork.

Step 2: Research one unfamiliar name. Pick one company outside your comfort zone. A mid-cap capital goods maker. A specialty chemicals company. A regional cement player. A B2B enterprise software name. Do not buy it. Just read the annual report, understand the business, and form an opinion. The goal is not to build a position. The goal is to break the mental habit of filtering the universe by brand recognition. Once you have researched one unfamiliar name, researching the second is easier. After five, the habit flips: unfamiliar stops feeling risky and starts feeling interesting.

Step 3: Size the familiar positions honestly. If after research you still believe HDFC Bank is worth holding, good. But ask yourself: if I did not already own it, would I buy it today at this price? If the answer is no, your current holding is an accident of familiarity, not a decision. Reduce it or exit it over time. If the answer is yes, keep it, but size it like any other position, not as a "safe core" that gets a free pass on valuation and growth checks.

SEBI's research on retail investor behaviour has repeatedly shown that concentration and unexamined holdings are among the largest sources of long-term underperformance. The data does not support the belief that holding what you know is safer than holding a diversified benchmark. In many cases, it is the opposite.

The Question Worth Asking Tonight

Pull up your portfolio before you sleep. Look at the top 10 holdings. For each one, ask a single question: would I buy this position at today's price and today's weight if I did not already own it?

If you answer no to more than three of the ten, familiarity bias has turned your portfolio into a museum of past decisions rather than a forward-looking bet. The names have not changed, but the reason you own them has become "because I already do." That is the trap.

The fix is not complicated. The fix is discomfort. Accept that you will hold companies whose brands you do not see on television and whose products you do not touch. That discomfort is the price of genuine diversification. The alternative is the portfolio that looks exactly like every other Indian retail portfolio, with the same underperformance and the same surprise when the familiar names let you down.

Frequently Asked Questions

What is familiarity bias in investing?

Familiarity bias is the tendency to invest in companies you recognise from daily life rather than companies that offer the best risk-adjusted return. In India this shows up as portfolios dominated by household names like TCS, Reliance, HDFC Bank, Infosys, and ITC, because investors see these brands on television, use their products, and feel they "understand" the business. The bias feels safe. It is not. It produces portfolios that all look identical and that miss the return drivers in mid-cap, small-cap, and sector-specific opportunities.

How is familiarity bias different from home bias?

Home bias is the tendency to hold domestic assets over international ones, so an Indian investor with 100% Indian equity exposure is showing home bias. Familiarity bias operates one level deeper. Within your Indian equity allocation, you still cluster in the same 10 household-name companies instead of diversifying across 50 names you do not recognise as easily. You can have home bias without familiarity bias, and familiarity bias without home bias, but most Indian retail investors have both at the same time.

Why is my HDFC Bank position not making money?

Between April 2021 and April 2026, HDFC Bank delivered roughly flat returns while the Nifty 50 gained approximately 50%. Infosys fell about 6% over the same period. The gap between Nifty and these two specific stocks is 50 percentage points or more. That is not a short-term anomaly. It is a structural underperformance driven by high valuations, slower relative earnings growth, and sector-specific headwinds. Your portfolio felt safe because the names are familiar. The market did not reward that feeling.

How do I know if I have familiarity bias in my portfolio?

Three tests. First, count how many of your top 10 holdings are household brands you would recognise without a ticker. If the answer is more than six, familiarity bias is likely. Second, check when you last researched a company whose products you never use. If the answer is "never", you are filtering your universe by familiarity. Third, run your Zerodha or Groww portfolio through PortoAI's overlap analysis. It compares your holdings to the aggregate Indian retail portfolio and tells you how closely you match. A match above 70% means you are paying for concentration you did not choose.

Does familiarity bias affect mutual fund investors too?

Yes, more than most SIP investors realise. If you hold three large-cap mutual funds, they likely all own Reliance, HDFC Bank, Infosys, ICICI Bank, and TCS in their top 10. You think you have diversified across three funds. You actually own the same 10 stocks three times, with extra expense ratio. PortoAI's SIP overlap analysis scans the top holdings of every fund you own and shows you how much of your SIP money is actually going to distinct companies versus duplicated exposure to the same names.

What should I do if I have familiarity bias?

Start with diagnosis, not action. Run your portfolio through an overlap analysis to see how concentrated you are in household names. Identify three companies whose products you do not use and whose earnings you have not tracked in the last year. Research them the same way you researched TCS. You do not have to buy. You have to break the habit of filtering the investable universe by what you already know. Once the habit is broken, diversification follows naturally.