William Eckhardt: the man who bet against the Turtles

The mathematician in the pit

Eckhardt met Richard Dennis when both were teenagers in Chicago, and their friendship survived two very different temperaments: Dennis the intuitive floor trader, Eckhardt the scientist. Eckhardt was pursuing a doctorate in mathematical logic at the University of Chicago when, in the early 1970s, Dennis persuaded him to leave academia and trade at the MidAmerica Commodity Exchange. He never went back. The two later ran C&D Commodities together, the research operation from which the Turtle experiment was launched.

The academic instincts never left him. Eckhardt has published work on probability and the philosophy of science, and he approached markets the same way: as a problem in statistics, where human intuition is not just unhelpful but systematically wrong.

His side of the bet

When Dennis claimed he could teach anyone to trade, Eckhardt's objection was specific: he believed the two of them had something innate, and that handing novices a rulebook would prove it. Rules could be taught, but the ability to follow them under pressure, he argued, could not.

The Turtles' results settled the headline question. The group reportedly made over $175 million, and Eckhardt has acknowledged that the experiment changed his mind: trading, he conceded, can be taught to a far greater degree than he believed. But the fine print favored him more than the legend admits. Outcomes across the Turtles varied enormously with identical rules, and what happened to the class afterward suggests that temperament decided who kept winning once the training wheels came off.

What Eckhardt taught the Turtles

Much of the intellectual content of the program, the parts covered in our rules guide, carries Eckhardt's fingerprints. Ideas he is associated with include:

• Don't think in trades, think in systems. Any single outcome is noise; only the expectancy of the whole process matters.
• Human nature is calibrated to lose. What feels comfortable, taking quick profits and giving losers room, is the exact opposite of what works.
• The stop is sacred. The trades people most want to hold past their stop are the ones that do the most damage.
• Size decides survival. Even a profitable system dies if positions are too large for its losing streaks.

Eckhardt Trading Company

In 1991 he founded Eckhardt Trading Company, managing client money with systematic programs descended from the same research tradition. The firm ran for decades with a track record that placed him among the most respected systematic traders of his generation, a quiet counterpoint to his reputation as the man who lost the bet. Losing it, he liked to point out, cost him a fraction of what being wrong about trend following would have.

Where to hear him directly

Eckhardt gives few interviews. The essential one appears in Jack Schwager's The New Market Wizards, where he lays out the psychology of systematic trading in detail, including his reflections on the Turtle experiment. It pairs naturally with the Dennis interview in the original Market Wizards: the two sides of the bet, in their own words.