Psychology of the stock market — Edition Insights

The Speculative Cycle and the Crowd Mind

Selden distinguishes between broad market movements, which he says always reflect general financial conditions, and the smaller intermediate fluctuations that represent changes in the public mind. The latter may or may not coincide with alterations in basic factors like dividend prospects or earning power. He reproduces a typical exchange between professional traders to show how quickly psychological contagion spreads: one trader covers his Steel short because he believes everyone else is short, only to find that each person has done the same for identical reasons. This recursive reasoning, Selden suggests, creates self-reinforcing cycles that can detach prices from underlying value. The chapter establishes that the market's minor waves are driven less by news than by traders' perceptions of what others are thinking.

Inverted Reasoning and the Bias of Self-Interest

Selden argues that most traders invert logic: instead of fitting their interests to the facts, they try to make the facts fit their desires. He writes that "few persons are so introspective as to be able to tell where this bias in favor of their own interests begins and where it leaves off." The market, he insists, is relentless and cannot be budged by sophistries. Success requires forgetting one's own position—profits, losses, entry price—and focusing solely on what the market is doing. He criticizes arbitrary rules like taking a fixed profit of seven points in Union Pacific, calling such attempts to "make the market fit itself around his own trades" foolish. The more a trader dwells on his personal stake, Selden warns, the more his judgment becomes warped, blinding him to contrary evidence.

The Trap of Consistency and the Value of Volatility

Selden observes that a strong will and logical intellect can be liabilities in speculation. He quotes an unnamed source: "In the market, to be consistent is to be stubborn." The man of firm conviction often underperforms the "more shallow and volatile observer, who is ready to whiffle about like the weathercock at any suspicion of a change in the wind." This is because commitment to a position—whether long or short—breeds irrationality. Selden notes that brokers often advise taking small profits to prevent customers from holding on until they take a loss, a policy he deems sensible only when neither broker nor customer has real market knowledge. For the scientific trader, the only question is what the market will do next; personal profits and losses should be irrelevant to that judgment.

Selden's work remains a concise primer on the cognitive pitfalls that distort trading decisions. Readers should note that the excerpts cover only the first two chapters and part of the third; the book also addresses panic and boom psychology, scale orders, and the individual's mental attitude. The analysis is grounded in early twentieth-century market practices—ticker tape, floor trading, café conversations—but the psychological principles Selden identifies, such as the difficulty of separating personal interest from objective analysis, have proven durable across market eras.