--- title: "Herd Behaviour and Market Bubbles | RupeeCase Learn" description: "Why smart investors follow crowds into obvious bubbles | information cascades, FOMO, and how herding creates both the worst risks and best opportunities." source_url: "https://www.rupeecase.com/learn/path-8/module-8-4-herd-behaviour-and-market-bubbles" --- Skip to main content [Learn](/learn)›[Path 8: Behavioural Finance](/learn/path-8)›Module 8.4 # Herd Behaviour and Market Bubbles Everyone knows tulip mania, dot-com, and 2008. What's less understood is why intelligent, otherwise rational people keep following crowds into obvious bubbles. The mechanism is the same every time | and it's more rational than it looks. TK Tanmay Kurtkoti Founder & CEO, RupeeCase · QC Alpha ⏱ 13 min read ⟳ Updated 16 Jun 2026 ◆ Intermediate In 2021, one particular small-cap stock rose 400% in 11 months. It had no meaningful change in business fundamentals. The company's revenues were declining. But social media groups were buzzing, YouTube channels were breathless with excitement, and the stock appeared on every retail momentum screen. Millions of new investors bought it. When the bubble burst, many lost 70-80% of what they'd put in. This is herd behaviour at its most vivid. Four Indian bubble cycles | the anatomy of collective delusion Every cycle looks different in theme. The mechanics are identical. 72% median peak to trough drawdown across the last 4 Indian bubble baskets Nifty sub indices 2000 to 2023 48% share of 2021 small cap buyers who opened their first demat after March 2020 CDSL data 34% of new retail equity buys traced to WhatsApp or Telegram tip sources in 2021 SEBI investor survey 2022 22 months average bubble lifespan from retail mania onset to full drawdown QCAlpha cycle database Bubble lifecycle | five phases the crowd walks through without noticing 1 Stealth smart money accumulates, fundamentals lead price 2 Awareness institutions pile in, media starts noticing 3 Mania retail surges in, valuations detach, price leads story 4 Blow off euphoria peak, every concern dismissed, volume maximum 5 Unwind smart money exits, retail holds the peak, 60 to 80% drawdown 2021 small cap mania | who was actually buying Buyer composition at the 2021 peak First time demat opened post Mar 2020 48% Retail veterans chasing momentum 27% HNI and family office allocation 16% Domestic mutual funds and FII 9% FOMO trigger | what actually pushed the buy WhatsApp or Telegram tip 34% YouTube finfluencer call 26% Friends and family buying 22% News headline or broker report 18% Peak to trough drawdowns | the cost of being late to the crowd 2000 IT basket -87% 2007 realty and infra -82% 2021 SME platform stocks -68% 2017 small cap 250 -64% Nifty 50 TRI worst drawdown -29% SEBI NSE BSE NSDL CDSL **TK | December 2007, my first bonus.** I was 22. My first corporate bonus hit the bank account | 4.6 lakh. The news was full of India's infrastructure story, realty was on fire, and every uncle at every family function had a tip for a midcap that was going to triple. I put the entire amount into a basket of realty and infra midcaps across three weeks in December 2007. No process, no position sizing, no stop. By October 2008 that basket was down 76%. 3.5 lakh gone. The market recovered most of its levels within 18 months. Those stocks did not. Most of them never got back to 2007 highs even by 2014. That loss taught me the single most important lesson of my career | when everyone around you agrees on a trade, the trade is already over. The crowd is never early. If you're buying what the crowd is buying, you're the exit liquidity. ## Why herding is individually rational but collectively catastrophic Herd behaviour | following the crowd's investment decisions rather than forming independent judgments | seems irrational. But it's individually rational for several reasons: * **Information cascade:** Other people's actions contain information. If thousands of investors are buying a stock, perhaps they collectively know something you don't. Acting on others' actions rather than your own limited analysis is an efficient way to process information | when the crowd is genuinely informed. * **Career risk (for fund managers):** A professional fund manager who underperforms the benchmark while holding different stocks faces career consequences. Holding the same stocks as everyone else ("closet indexing") means your underperformance is at least in line with peers. Rational self-preservation, collectively harmful. * **Social proof:** When everyone around you is making money in a particular theme (2021 small-caps, 2017 mid-caps), the social pressure to participate is intense. Not participating feels like missing out and being wrong. The problem: when the crowd's actions are driven by each other's actions rather than fundamental analysis, the information cascade carries no real information. Everyone is following everyone else. The resulting price movements are entirely disconnected from underlying value. ## How bubbles form and burst | the Indian pattern India has produced several identifiable bubbles in the last 15 years. The pattern is consistent: * **Phase 1 | Smart money:** A genuinely attractive theme (infrastructure, mid-caps, new listings) attracts informed investors. Prices rise on legitimate fundamental improvement. * **Phase 2 | Fast money:** Rising prices attract momentum traders. Returns are now driven by price appreciation rather than fundamentals. Valuations stretch. * **Phase 3 | Retail frenzy:** Strong returns attract retail investors who see others making money. SIP inflows surge. New demat accounts open. Social media amplifies. Valuations become extreme. * **Phase 4 | Euphoria and denial:** Any concern is dismissed ("this time is different," "India's growth story," "retail participation has changed the game permanently"). Volume is maximum. Everyone is bullish. * **Phase 5 | Collapse:** Smart money exits. Fast money follows. Retail is left holding the peak. The same stocks that rose 300-400% fall 60-80% over 18-24 months. **The contrarian insight:** The presence of extreme herding is a reliable signal | in both directions. Maximum retail enthusiasm near a peak signals overvaluation. Maximum retail pessimism near a trough signals undervaluation. The contrarian investor tracks sentiment indicators (SIP flows, demat account openings, social media sentiment) as contrary indicators to fundamental analysis. Indian Market Bubble Timeline, Peak to Trough BSE/NSE data, AMFI | Bubble / Theme | Peak year | Peak-to-trough fall | Recovery time | | --- | --- | --- | --- | | IT / Dotcom stocks | 2000 | −70% to −90% | 5 to 7 years | | Real estate (DLF, Unitech) | 2007 to 08 | −85% to −95% | Never (many) | | Infrastructure stocks | 2007 to 08 | −75% to −90% | 8 to 12 years | | Mid/small-cap rally | 2018 | −40% to −65% | 2 to 3 years | | SME / micro-cap IPOs | 2024 | −50% to −80% | Ongoing | In every case, retail participation peaked just before the collapse. Maximum SIP inflows, demat account openings, and social media discussion coincided with the price top, not the bottom. ## FOMO | the herd behaviour amplifier **FOMO (Fear Of Missing Out)** is the specific emotional mechanism that drives retail investors into bubbles at their peak. When a stock or sector has already risen 200-300% and social media is full of success stories, the psychological pressure to participate becomes overwhelming | even for investors who intellectually know the price is stretched. FOMO is especially dangerous because it creates an asymmetric risk scenario: potential gains are limited (the stock has already risen enormously) while potential losses are large (the bubble can collapse). Yet the emotional pull feels exactly opposite | gains feel likely and certain, losses feel unlikely. Systematic protection from herding at RupeeCase RupeeCase strategies buy and sell based on quantitative factor signals, not social sentiment or recent price performance alone. A stock that has risen 400% in a year may actually be flagged for exit (if momentum has peaked and quality scores are declining) rather than entry. The systematic approach is inherently contrarian to herd extremes | adding exposure when factors are improving and reducing when they're deteriorating. Start at [invest.rupeecase.com](https://invest.rupeecase.com). ## Glossary Key terms | Module 8.4 Herd behaviourFollowing the crowd's investment decisions rather than independent judgment. Individually rational (others' actions carry information) but collectively catastrophic when everyone follows everyone else. Information cascadeWhen people act on others' actions rather than their own private information, passing the same (possibly incorrect) signal down the chain. Creates self-reinforcing price movements disconnected from fundamentals. FOMOFear Of Missing Out | the emotional pressure to participate in a rising market/stock because others are visibly profiting. Typically most intense at or near market peaks | precisely the worst time to enter. Closet indexingFund managers holding portfolios nearly identical to the benchmark index to avoid career risk from underperformance, while charging active management fees. A form of professional herd behaviour. RC **Want to put this into practice?** RupeeCase is the systematic investing terminal built around everything you're learning here, factor scores, strategy backtests, portfolio construction for Indian markets. [Explore the terminal →](https://invest.rupeecase.com) #### Sources & further reading * → [SEBI | Investor Education (behavioural aspects)](https://www.sebi.gov.in/sebiweb/other/OtherAction.do?doRecognisedFbo=yes&intmId=31) * → [AMFI India | Monthly SIP flow data (tracks retail sentiment cycles)](https://www.amfiindia.com/research-information/mf-data) * → [NISM Series X-A | Herding and market microstructure](https://www.nism.ac.in/resources/study-material/) TK A note from the author What Indian market bubbles taught me about crowd behaviour I watched the 2007 real estate bubble from close quarters. Smart people, people with MBAs and CFAs, were putting their entire net worth into real estate stocks because “India is different” and “real estate only goes up.” DLF went from ₹1,000+ to under ₹100 in 18 months. The lesson isn’t that crowds are always wrong. It’s that by the time you feel the urgency to join a trade, the best returns are already behind you. Momentum strategies capture crowd behaviour early and systematically, they don’t wait for narratives to become consensus. TK Tanmay Kurtkoti Founder & CEO, RupeeCase · 17 years systematic trading · QC Alpha ### Quick check, Module 8.4 0 correct · 0 answered ✓ Module complete! Next module unlocked. 🎉 Module 8.4 complete 3 correct. Continue to Module 8.5 when ready. RupeeCase Terminal Put this into practice Factor strategies, backtesting, portfolio analytics, systematic investing for Indian markets. [Try RupeeCase Terminal →](https://invest.rupeecase.com) 🎓 Spread the knowledge This course is free. Help someone else learn about Herd Behaviour and Market Bubbles, share it with one person who needs this. 📋 Suggested LinkedIn post, copy & paste Just completed Module 8.4 of Tanmay Kurtkoti's free investing course on RupeeCase. Learning about Herd Behaviour and Market Bubbles. Completely free at rupeecase.com/learn Copy text Share on X Post on LinkedIn Copy link Research Lab Qualifier Path 8, Module 4 of 6 done, complete all 6 + path test to unlock [Explore terminal →](https://invest.rupeecase.com) ✅ 8.1→ ✅ 8.2 to 8.3→ 📍 8.4 Herding→ 8.5→ 8.6 [← Previous](module-8-3-cognitive-biases-overconfidence-anchoring-recency.html) Previous, Module 8.3 Cognitive Biases Overconfidence Anchoring Recency Calculator ### Bubble Risk Indicator Bubble warning composite. Three inputs that historically correlate with late-stage frothy markets in India. Nifty 50 trailing P/ESmallcap 250 / Nifty 50 P/E ratioRetail SIP inflow growth YoY (%)VIX (India) Quick check, Module 8.4 ## 3 questions. Get 2 right to mark this module complete. 0 of 3 answered ✓ Module complete. Keep going. Up next, Module 8.5 The Disposition Effect and How to Beat It The single most wealth-destructive behaviour pattern in equity investing | selling winners and holding losers | and the systematic architecture that prevents it. [Continue →](module-8-5-disposition-effect-and-how-to-beat-it.html) PRACTICE WHAT YOU LEARNED Try systematic strategies on RupeeCase | free paper trading. [Get Started Free →](https://invest.rupeecase.com/signup) Related on RupeeCase [PodcastEP16: Squeeze or the beginning?Thu 9 Apr, managing emotion](/podcast/episodes/2026-04-09.html) [DailyWhen narrative meets priceMid-week reality check](/daily/2026-04-16-squeeze-printed-pro-just-flipped-short.html) [CompareRules vs discretion, long horizonProcess beats conviction](/compare/rupeecase-nifty-vs-kotak-emerging-equity.html) [ToolsJournal template and checklistsBuild your process](/learn/tools.html) [StrategyAllCapRules beat feel | 50 names | no discretion](/strategies/allcap.html) © 2026 RupeeCase by QC Alpha · [rupeecase.com](https://www.rupeecase.com) · [All learning paths](https://www.rupeecase.com/learn) Newsletter ### What's working, what isn't. Strategy launches, monthly performance notes, and podcast calls that printed. Two or three emails a month. Built for people who actually read them. Subscribe By subscribing you agree to our [Privacy Policy](/privacy-policy.html). RupeeCase is not a SEBI registered Investment Adviser. Nothing in the newsletter is personalised investment advice. Built on India's regulated market infrastructure NSE Order routing BSE Backup venue SEBI Markets regulator NISM Certified author [About](/about.html). [Pricing](/pricing.html). [Risk Profile](/risk-profile.html). [Tools](/learn/tools.html). [Blog](/blog/). [Track Record](/track-record.html). [Sitemap](/sitemap.html) [Privacy Policy](/privacy-policy.html). [Terms](/terms.html). [Disclaimers](/disclaimers.html). [Grievance](/grievance.html) RupeeCase is brought to you by Tanmay Kurtkoti. [Sign In](https://invest.rupeecase.com/login) [Get Started](https://invest.rupeecase.com/signup)