What 200,000 Prediction Market Fills Reveal About the World Cup

TL;DR: Analysis of Kalshi's KXMENWORLDCUP-26 winner markets across ten national teams — over 200,000 fills — reveals three patterns that end-of-day prices miss entirely: the USA's repricing from 9.2% to 27% is visible at hourly resolution before daily VWAP catches up; post-win spikes in illiquid markets inflate daily averages past the point of usefulness; and France's 63,000-fill sustained climb is the cleanest win-probability signal in the tournament.

Data covers trades through June 22, 2026. VWAP computed at monthly granularity for the pre-tournament period and hourly granularity since June 11.

The USA: 9.2% to 27% across three game nights

Before the tournament, Kalshi's markets gave the USA a 9.2% chance of winning — ninth out of ten teams tracked, in their own tournament. The move to 27% happened across three distinct sessions and is visible hour by hour.

1. June 12–13 (first game): Game ended ~23:30 UTC June 12. Within one hour, 1,317 fills pushed price to 0.27. Sellers pushed back to 0.10–0.14 overnight — a contested result, not a blowout, and the fills show the disagreement.
2. June 14 (second game): A second repricing ran to 0.55–0.62 across 394 fills, then settled as the result cleared.
3. June 19 (third game): 3,374 fills in four hours — the highest-volume window for the USA market all tournament.

Three games happened and each repriced the market. That is visible in the hourly VWAP before the daily number reflected it. The fills show the exact moments when the market changed its assessment and how much volume backed each move.

Post-win spikes: what Argentina's 88% and Brazil's 78% actually mean

At 00:00 UTC on June 13 — roughly 30 minutes after Argentina's first game — the outright market printed 0.884 on 74 fills. By 02:00 UTC it was back at 0.10. The daily VWAP for June 13 came out at 0.46.

None of these figures represent Argentina's actual assessed win probability. The midnight spike is the structural result of buyers reacting before sellers arrive in an illiquid market. The 0.46 daily average is a mathematical artefact of the spike and the correction taken together. Argentina's settled level — once the market filled in — was 0.12–0.25, currently 0.252.

Brazil followed the same pattern one night later: game ended ~23:00 UTC June 13, price reached 0.78 by 10:00 UTC June 14 on 26 fills, then fell to 0.11 by noon. Daily VWAPs of 0.328 and 0.318 for June 14–15 are artefacts of the same mechanism.

This pattern is repeatable and predictable: every thin outright market shows it after a positive result. End-of-day prices capture the artefact. The fills show the correction.

France vs Spain: same starting price, opposite trajectories

France entered May at 0.303, Spain at 0.263 — close enough to read as co-favourites. Twelve days in, the markets tell different stories.

France's daily VWAP since tournament open:

0.188 → 0.204 → 0.234 → 0.290 → 0.300 → 0.295 → 0.302 → 0.353 → 0.363 → 0.355

No single spike. 63,000 fills across 12 days. Consistent buying as results arrive.

Spain peaked at 0.399 on June 16 — the day after a 0–0 draw with Cape Verde — then pulled back steadily to 0.270. Their current price is almost identical to the pre-tournament May VWAP of 0.263. The market is pricing Spain as a team meeting expectations.

France at 35.5% across 63,000 fills is the most reliable win-probability estimate in this tournament so far.

The data

Every fill is timestamped with price and size. VWAP is computable at any granularity — hourly resolution exposes spikes and corrections that daily resolution averages away. Matched against match results, the dataset identifies exactly when new information entered the market and how quickly it was absorbed.

The three patterns above — the USA's session-by-session repricing, the Argentina and Brazil artefacts, the France/Spain divergence — are not visible from end-of-day price data. They require the fills.

All data from the Probalytics ClickHouse database (probalytics.fills joined against probalytics.markets). Markets queried: KXMENWORLDCUP-26-* on Kalshi only. VWAP = sum(price × size) / sum(size) per period. Thin-market prints (under 50 fills/hour) noted where they drive daily figures.