22% — Who will be the Heavyweight Title on Dec 31, 2026
Kalshi 22% · 4 contracts · $9K volume · medium confidence
Updated 2026-09-22 00:23:58 UTC

Why this matters:
This probability estimates the likelihood that Tom Aspinall will hold the UFC Heavyweight Championship on December 31, 2026. At 66%, markets view Aspinall as the clear favorite to retain or regain the title by year-end, though Ciryl Gane (25%) represents a meaningful alternative outcome. The pricing reflects Aspinall's current standing in the heavyweight division and the historical difficulty of dethroning a champion within a specific timeframe. Between now and year-end, scheduled title fights, injury announcements, or unexpected upset results would be the primary drivers of probability shifts. Any title defense Aspinall loses or major fighter injury would significantly alter these odds. The resolution depends entirely on who officially holds the belt on the final day of 2026, making upcoming scheduled championship bouts the critical catalyst for clarity.

Key factors:
- Tom Aspinall's current championship status and scheduled title defense dates between September 2026 and December 31, 2026
- Ciryl Gane's ranking, recent performance record, and likelihood of earning a title shot within the specified timeframe
- Josh Hokit's and other contenders' positions in the rankings and probability of ascending to a title fight
- Injury risk to Aspinall or other top contenders that could alter the championship landscape
- Historical turnover rates in the UFC Heavyweight division and average time between title changes

Contracts:
- Who will be the Heavyweight Title on Dec 31, 2026?: Josh Hokit — 18¢ Kalshi $5K (weight 56%)
- Heavyweight Title holder to be vacant on Dec 31, 2026: Vacant — 3¢ Kalshi $2K (weight 20%)
- Who will be the Heavyweight Title on Dec 31, 2026?: Ciryl Gane — 59¢ Kalshi $2K (weight 18%)
- Who will be the Heavyweight Title on Dec 31, 2026?: Alex Pereira — 8¢ Kalshi $491 (weight 6%)

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## Methodology

SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours.

## SF Signal

- SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration.
- No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only.

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*Last verified: 2026-09-21T23:20:55.652Z*

By SimpleFunctions — https://simplefunctions.dev/

Cite as: "22% per prediction markets (SimpleFunctions, September 2026)"
Canonical: https://simplefunctions.dev/answer/ufcheavyweighttitle
Full data: https://simplefunctions.dev/api/public/query?q=Who%20will%20be%20the%20Heavyweight%20Title%20on%20Dec%2031%2C%202026
Provider: SimpleFunctions — https://simplefunctions.dev