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Mean reversion to a quality-backed trend

Prices wander around a longer-run path — running ahead of it when investors get excited, falling behind it when they panic — and then tend to pull back toward it. That pull-back ("mean reversion") is one of the oldest ideas in markets. But there's a vital condition most people skip: the long-run path is only trustworthy if the business behind it is genuinely good.

What it is

Two things that look identical on a price chart can be opposites underneath. A quality business that's been knocked down for a temporary, fixable reason behaves like a beach ball held underwater — push it down and it springs back the moment you let go. A weak business in genuine decline behaves like a falling knife — it looks cheap all the way to zero. The chart can't tell them apart. The quality of the underlying business can.

Why it matters

This is the difference between a bargain and a value trap, and it's where a lot of "cheap" investing goes wrong. "It's fallen 70%, surely it'll bounce" is only true if the franchise is intact and the problem is temporary. If the decline is structural, cheap just gets cheaper.

How we use it

We hunt for good businesses knocked down for temporary reasons, and we use the short-term overshoots to time our entry — buying into the dips toward the trend rather than chasing the pops away from it. We also think in percentages, not price points: a £2 move on a £200 share is a 1% wobble, which looks dramatic on a chart but is just ordinary noise — and mistaking normal volatility for a breakdown (or a breakout) is how charts fool people.

The honest caveat

This is a principle we are actively testing on our own data, not a settled law. Reversion can take years to arrive, and "quality" has to be demonstrated — profitable, durable, well-financed — never just assumed because a name is familiar. We treat this as a work-in-progress thesis and will update it as the evidence comes in.

A plain-English explainer of how we think — part of our evidence-driven framework. Not investment advice.