W.E.T. Favorites Combo Index: methodology

The W.E.T. Favorites Combo Index is a daily 0–100 reading of how strongly the market backs tonight's favorites across the major leagues — and the clearest demonstration of what this desk does.

Components

Active moneyline markets for games settling inside the daily window (MLB, NBA, NHL across Kalshi, Polymarket and Gemini). Derivative lines — totals, spreads, handicaps, prop counts — are excluded: this index reads who wins, not by how much. Each game contributes once, through its favorite.

Value

The volume-weighted mean favorite probability across games, 0–100. No single game may exceed 20% of the weight.

The combination reading

A sportsbook would call these legs a parlay; priced properly it is a combination — the probability that every leg lands at once. The basket page prices both readings of the identical holdings: the diversified spread (what the index tracks) and the multiplicative combination, bounded by the Fréchet–Hoeffding inequalities because the legs are not independent. Seeing the two numbers beside each other is the point: the combo pays more because it is a far worse risk, and that difference is arithmetic, not opinion.

W.E.T. handles no orders. Every holding links to the venue that lists it.

What this index is not

This is a benchmark reading of market prices, not a W.E.T. forecast and not advice. A high value does not predict that the event happens — it reports what prediction-market traders are collectively pricing right now. Prices move continuously and can be wrong.

An accuracy record for a benchmark requires resolved outcomes accumulated over time. W.E.T. publishes this index daily with a dated, immutable history from first publication — that published series is the audit trail. Calibration analysis will ship strictly when the resolved-outcome corpus supports it, never before. See the site methodology for the same discipline applied to the W.E.T. Score.