01
What a regression spread is
A price ratio assumes one unit of A is hedged by one unit of B. Regression fits the proportion to the data instead, and what is left over is the spread.
Method
Every pair page here reports five numbers. These pages explain what each one is measuring, how it is computed, and where it stops being informative.
02
Hedge ratio (beta)
Beta is the slope of the fit — how many units of exposure to the second leg balance one unit of the first. It is a sizing number before it is a statistic.
03
Spread z-score
The z-score turns "the spread is 0.08 above the fit" into "that is further than this pair usually strays" — the step that makes different pairs comparable.
04
Half-life of mean reversion
A z-score says how far out a spread is. Half-life says how long it has historically taken to come halfway back — the difference between a trade and a wait.
05
Correlation and cointegration
Correlation describes how two assets moved together day to day. It says nothing about whether they stay tethered — which is the property a pair trade depends on.
06
The BTC/ETH ratio
One number says how many ETH a bitcoin buys. On its own it means nothing — this is how to turn it into a statement about whether right now is unusual.
07
Pair trading, and how it differs from buying
Buying is a bet on direction. A pair is a bet on the distance between two assets — a different risk, a different timescale, and a different way of being wrong.
These pages describe how the site computes its metrics. They are not trading advice and not a recommendation to enter any position.