Bill Dunn built one of the most disciplined trend following operations in the history of systematic trading. Dunn Capital Management ran a 100% mechanical trend following system — no discretion, no overrides, no human judgment applied to individual trade decisions. The system followed the rules. The trader followed the system.
His approach is captured in A Day in the Life at Dunn Capital, which documents what a fully systematic trend following operation looks like in practice.
The Core Insight: Volatility Is Not the Enemy
The goal of the trend follower is to take what is given. If you want to trade right you cannot say to yourself, “I want 15% a year.” The market cannot be ordered to give you a steady 15% a year. You must expect volatility.
Consider which you would rather have: three years of +15%, +15%, and +15%, or three years of -5%, +50%, and +20%? At the end of three years the first investment opportunity would be worth $1,520 (starting with $1,000). The second would be worth $1,710. This is the world of Bill Dunn.
Large gains make up for small losses. Smooth is not the same as good. This insight is one of the most important in trend following and one of the least understood by conventional investors. The institutional investment industry trains clients to equate volatility with risk. Dunn’s career is evidence that a strategy willing to accept volatility in both directions can compound wealth faster than one that sacrifices returns to maintain a smooth equity curve.
Dunn Capital and the 1995 Japanese Yen: A Case Study in Mechanical Trend Following
Dunn Capital Management in 1995 returned +96.7% for the year. The primary driver was the Japanese Yen — one of the most dramatic currency trends of that decade. The monthly return breakdown:
| Feb-95 | Mar-95 | Apr-95 | May-95 | Jun-95 | Jul-95 | Aug-95 | |
|---|---|---|---|---|---|---|---|
| Dunn Capital | 13.7% | 24.4% | 3.8% | (2.6%) | (3.6%) | 0.6% | 18.5% |
Dunn Capital is a long-term reversal trend follower that exploited the Japanese Yen to extreme levels in 1995. The firm made money going up that huge mountain in February of 1995 and made money going down that huge mountain in August of 1995.
Look at the monthly returns alongside the chart of the Yen. The correlation between gains and losses and the ups and downs in the chart pattern is direct. Dunn initiated the position in January 1995 and rode it until the top. The position was reversed on the downside of the first peak. The reversal was short-lived, as the spike back upward shows. Then came the extended steep downside reversal that the system followed.
Dunn initiated a short position in the Yen after the first peak and did not exit the position even when it moved against him. He stayed in the position with mounting losses. However, the losses at no point approached his entry position on the short side. Consequently the system sat there with discipline and waited. The flat and loss period from April to June 1995 in the returns corresponds to the same flat period in the chart. The large downside move rewarded that patience.
This was not seat-of-the-pants trading. There were precise rules. Dunn’s system is 100% mechanical. And by and large Dunn’s past returns are correlated to other trend followers.
What the 1995 Yen Trade Teaches About Trend Following
The system held through the drawdown. The April to June flat and loss period was the critical test. A discretionary trader would have exited. The system did not. The rules said stay in. The position stayed in. The eventual payoff in August — 18.5% in a single month — was the reward for that discipline.
This pattern appears throughout the history of systematic trend following. The largest returns come from positions held through periods of pain. The traders who generate extraordinary long-term results are those whose systems and whose psychology can sustain a position when it is moving against them, as long as the original trend signal remains valid.
Both directions of a trend are tradeable. Dunn made money on the way up in February and March and money on the way down in August. A trend following system does not require a bull market. It requires movement in any direction. The ability to go short and to reverse positions as trends change is one of the structural advantages of systematic trend following over long-only investment approaches.
Mechanical systems remove the most dangerous variable: the trader. The reason Dunn’s system worked in 1995 is the same reason it worked across his entire career. The system did not second-guess itself. It followed the rules. The TurtleTrader rules were built on the same foundation — a mechanical system removes the psychological weaknesses that destroy most traders and replaces them with a process that can be trusted and repeated.
Key Facts About Bill Dunn and Dunn Capital
- Founder of Dunn Capital Management, one of the longest-running systematic trend following firms
- Ran a 100% mechanical trend following system with no discretionary overrides
- Returned +96.7% in 1995, driven by the Japanese Yen trade
- Returns correlated to other systematic trend followers as expected from a rules-based approach
Frequently Asked Questions About Bill Dunn and Dunn Capital
What is Dunn Capital Management?
Dunn Capital Management is a systematic trend following firm founded by Bill Dunn. It ran a 100% mechanical trading system across global futures markets with no human discretion applied to individual trade decisions. It is one of the clearest examples on record of what a pure, rules-based trend following operation looks like.
How did Dunn Capital return 96.7% in 1995?
The return was driven by the Japanese Yen, which experienced one of the most dramatic sustained directional moves of that decade. The system captured the trend in both directions — riding it up in the first half of the year and short on the way down in the second half. The key was the discipline to hold a short position through mounting losses in April to June, before the large downside move came in August.
What is a 100% mechanical trend following system?
Every trade decision — when to enter, when to exit, how large the position should be — is determined by the rules of the system, not by human judgment. There are no overrides, no discretionary calls, no exceptions. The system is tested, the rules are set, and execution follows automatically. This is the same philosophy behind the TurtleTrader rules and the foundation of every serious systematic trend following operation.
Why did Dunn hold a losing position in the Yen?
Because the system said to. The rules defined the conditions for exiting the position, and those conditions had not been met. The losses in April to June were within the parameters the system expected. A discretionary trader might have exited to stop the pain. A mechanical system does not experience pain. It follows the rules until the rules say otherwise. The large downside move in August justified that discipline.
Is volatility the same as risk in trend following?
No — and this is one of the most important distinctions in systematic trend following. The comparison of smooth 15% annual returns versus a volatile sequence that ends higher is the clearest illustration. Volatility is the cost of the large gains that trend following produces. A strategy that eliminates volatility also eliminates the possibility of capturing the outlier moves that drive long-term performance.
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