Behavioral Finance

Learning objectives

By the end you can:

1. Explain why the market is structurally a machine for exploiting your psychology: how price is the crowd's consensus, why beating it requires being differently right (M6.02's second-level thinking), why the same biases that create the mispricing also live in your own head, and why the market presents maximal temptation at exactly the worst moments.
2. Describe Kahneman's System 1 and System 2 and locate precisely where in the analytical process investing errors are born, in the fast, intuitive snap judgment that System 2 then lazily rationalizes rather than checks, and explain why a written process is the only reliable fix.
3. Use prospect theory: reference dependence, loss aversion (~2×), diminishing sensitivity, and the reflection effect. Use them to explain the disposition effect (riding losers, selling winners) and reproduce the empirical numbers (Odean's PGR/PLR and the performance gap).
4. Name the mechanism, the specific investing failure mode, a real market example, and the counter-practice for each of the eleven core biases: anchoring, confirmation, loss aversion, recency, overconfidence, herding, sunk-cost, narrative fallacy, availability, hindsight, and endowment.
5. Work Munger's "Psychology of Human Misjudgment": group the ~25 tendencies sensibly, teach the six highest-leverage ones in depth (incentive-caused bias, social proof, commitment/consistency, deprival-superreaction, envy, authority), apply "show me the incentive and I'll show you the outcome," and explain the Lollapalooza effect with a worked case where four or more tendencies stacked.
6. Explain Soros's reflexivity, the two-way feedback loop in which perceptions change fundamentals which change perceptions, trace a boom-bust sequence, and identify the situations (financials, serial acquirers, anything where confidence is itself a fundamental) where it dominates.
7. Apply Marks's sentiment model, the pendulum and the three stages of both a bull and a bear market, and show how it is simply the individual biases summed to a market-level force you can take the temperature of.
8. Assemble the behavioral edge: map each bias to its specific counter-practice (checklist, decision journal, pre-commitment, environment design) and explain why process, not willpower or intelligence, is the only thing that reliably defeats a System-1 error.

Prerequisites & connections

Builds on. M6.03 supplies the rational baseline this module measures human behavior against: base rates and the outside view are the cure for narrative fallacy and recency; expected value and probabilistic thinking are what loss aversion and the reflection effect distort; calibration and ruin-avoidance are what overconfidence attacks; inversion and the pre-mortem are structured defenses against confirmation bias. Where M6.03 taught you how a good decision should be made, M6.04 explains why it usually isn't. From M6.01 come Graham's Mr. Market (the manic-depressive partner) and "the investor's chief problem, and even his worst enemy, is likely to be himself," the founding behavioral insights of value investing, predating the academic field by decades. M6.02 showed that every school is, at bottom, a pre-commitment device against a specific bias (Klarman's cash discipline against greed and the institutional imperative; Fisher's hold-forever against overtrading; the Magic Formula's mechanical rank against discretionary panic), and Marks's pendulum (M6.02 §4.6) is extended here. M2 (all) matters because every forensic red flag you learned to spot exists because a human was incentivized to create it and other humans were biased enough to miss it; the frauds in M2.08 are behavioral case studies as much as accounting ones.

Feeds forward. M6.05, the phase capstone, is where your personal checklist gets its behavioral lines and where the behavioral self-audit you run in §practice becomes a permanent instrument. The Mental-Model & Moat Checklist produced in M6.05 has an entire "behavioral self-audit" section that this module authors the content for. The whole of Phase 9 (M9.01–M9.04) is the behavioral edge operationalized: position sizing (against overconfidence and hidden correlation), the five sell disciplines (against the disposition effect, sunk cost, and endowment, in M9.03), and the decision journal and calibration loop (against hindsight and overconfidence, in M9.04) are this module's §4.8 turned into a running process. M7.05 takes cycles, bubbles, and crises: the Minsky and Kindleberger anatomies are the macro-scale expression of the reflexivity and Lollapalooza dynamics taught here, and the 2008, dot-com, and Japan case studies are behavioral finance at national scale. In M8.04, the deep dive's Day 3 "steelman the bear" and "pre-mortem" are direct antidotes to confirmation bias and overoptimism. Competency C9 in the master map, "an investor's temperament and process," is certified partly here (the bias-spotting gate) and completed in M9.