The same company, with no fundamental change, can double in market value within a year and then fall back to where it started. Over that year, what changed about the company? The same factories, the same orders, not one number moved. What moved was whoever quoted the price.
In the textbook the market is efficient: prices reflect all known information, valuation is precise, and nobody can take advantage of anybody. Clean, elegant — missing only one thing: it exists only in textbooks. The Mr. Market of reality is a manic-depressive, violently unstable. In his manic phase, everything deserves a sky-high price and a story can pass for ten years of profits; in his depressive phase, even gifts feel too hot to hold and good assets get cut in half all the same. His quotes are often laughably absurd. New-energy vehicles, liquor — an industry’s fundamentals do not transform overnight, yet share prices can surge and crash. What moves is never the industry; it is the mood of Mr. Market himself, swinging. The textbook calls this swing noise and assumes it averages out in time; Mr. Market’s moods never average out — they only alternate.
Why read this case file? Because the market’s irrationality is the entire source of long-term returns. Where does the mismatch come from? From the patient’s moods — one manic phase sends prices flying, one depressive phase smashes them through the floor; cheapness lives in the gap between two episodes. If the market were always efficient, if price always equaled value, every investor would receive the same average return; no excess return would exist anywhere. The market’s irrationality, the unchanging weaknesses of human nature, is the foundation of long-term profit. Put another way, Mr. Market’s illness is not a defect of the market; it is the only service the market provides. Everyone takes quotes from the same patient: most take the quote as truth, a few take it as mood — and long-term returns come entirely from that gap. Read the sentence in reverse and it turns harsher: cure the market’s illness and the source of returns is strangled with it — a room priced with perfect precision is a room with nothing cheap to pick up.
First objection: markets are institutionalized now, priced by algorithms — Mr. Market got cured long ago. Institutions are run by people; the emotion just moved into a bigger room — a bigger room, but the temper did not shrink. The mismatch did not disappear, it migrated from single stocks to whole sectors: an entire industry goes mad together, then repays together; the absurdity of the quotes is undiminished. Whoever hunts for mismatches one stock at a time watches the mismatch change address.
Second objection: it is mad this time, but how does anyone know it is not right this time? Perhaps the fundamentals truly changed, the market is repricing, and the error belongs to the watcher. That cannot be ruled on the spot, so do not rule: do not guess whether this bout of madness is justified; watch only what does not change — the asset itself, the coordinates themselves. When a price turns absurd, write it down and wait for Mr. Market to finish swinging before speaking. Judgment belongs to coordinates written in advance, not to the mood of the day.
Third objection: if the market is efficient in the long run and inefficient in the short run, just hold and wait for reversion — studying the patient’s moods is superfluous. Short-term inefficiency is the window for buying; long-term reversion is the channel for cashing out; neither works without the other. And long-run efficiency is not a promise on a calendar — a statistic computed only in hindsight; for whoever holds, every day is still short-run. Whoever never studies moods never even knew the window was open — he is terrified at the deepest point of the depressive phase and euphoric at the peak of the manic phase — both times standing on the wrong side.
Hardest of all are those who mistake Mr. Market’s quotes for Mr. Market’s character: in the depressive phase the world is over; in the manic phase, wealth set free. A quote is weather, not a verdict.
So there is something to thank this illness for. Every time the real Mr. Market has an episode, he hands a quote slip to whoever has patience. What to hope for is never a smarter market; it is the next episode, same as always. Cure the market’s illness, and the returns die with it.
