Most traders talk about strategies, systems, or setups. Brent Penfold, the veteran futures trader behind IndexTrader.com.au prefers a different word: model. To answer what is a trading model, the distinction isn’t just semantic, it forces you to think about your trading in a way looser terms let you avoid.
One Word, Four Parts
A model, in Penfold’s framing, isn’t a single rule or a clever entry trick. It’s a complete approach to trading, built from four connected pieces:
- The set-up (when it’s appropriate to even consider a trade),
- the entry (where you actually buy or sell),
- the stop (where you get out if you’re wrong),
- and the exit (where you take your profit).
Strip away the branding and most of the industry is describing this same four-part structure under different names: “strategy,” “system,” “methodology,” “algorithm,” even “robot.” But fundamentally, what is a trading model if not a structure that organizes these elements coherently?
Why “Model” Beats “Theory”
Here’s where it gets sharper. Penfold draws a hard line between a model and a theory.
A model implies the rules are fully disclosed with zero subjective discretion, which means you can actually run it across a portfolio of markets and calculate hard numbers like expectancy and risk of ruin. In other words, defining what is a trading model separates codified rules from subjective guesswork.
A theory, by contrast, leaves wiggle room for interpretation. He points to Elliott Wave and W.D. Gann as examples: rich, interesting frameworks, but ones that resist being hard-coded into a testable rule set.
What is a trading model? Same Structure, Different Targets
What makes this concrete is seeing it applied to an actual price chart. Penfold runs a family of named models, and each one targets a different part of the same market structure as price swings from bottom to top: what is a trading model in practice is shown in these examples.
- Key Exhaustion — bottom picking, entering as a decline runs out of steam
- Key Level — retracement trend trading, entering once price pulls back and resumes the trend
- Key Breakout — breakout trend trading, entering once price pushes through a prior high
- Key Swing — mean-reversion trend trading, fading the move once it’s overextended
- Key Exhaustion — top picking, entering as the rally runs out of steam
Five different entries, five different points on the same chart, but every one of them is still answering the same four questions: when to look, where to get in, where to bail if wrong, where to take profit.
That’s the real test of whether something is a model or just a tip dressed up in technical language. If you can point to where on the chart it’s meant to trigger, and you can name its stop and its exit, it’s a model. If it’s just “buy when it looks like this,” it’s a theory wearing a model’s clothes.
