Combat sports: UFC and boxing

UFC 331 finished last night and its contracts are still the busiest thing in combat sports by two orders of magnitude.

Polymarket's Pantoja–Van moneyline took $2,134,357 in the past twenty-four hours and is marked at one-tenth of one percent. Tuivasa–Despaigne took $475,989, Aswell–Yoo $382,422, Menifield–Baraniewski $336,334. Every one of those fights has already happened.

The entire forward calendar trades $12,704 a day. Canelo Alvarez against Christian Mbilli on October 31 turns $7,628; Sandoval against Collazo on October 10 turns $5,076; the five UFC Fight Night bouts on September 26 turn $1,609 between them. The settled Pantoja contract alone out-traded the whole forward book by a factor of 168.

This is the third consecutive session the page has read this way, and the ratio is widening rather than closing. Combat books on both venues are settlement-day instruments: the money arrives when the outcome is already known and the price is a rounding error.

The forward money is two boxing cards five weeks apart, and they disagree about how a two-man market should add up.

Canelo vs Mbilli, October 31: 75% against 28%—a three-point overround on $71,939 of open interest. Sandoval vs Collazo, October 10: 49% against 48%—three points the other way, on $5,678. One book charges for the favourite; the other leaves money on the table.

The deepest forward book in combat sports, both sides. Canelo is 75% and Mbilli 28%. The two legs sum to 103, so the book is quoting a three-point vig on a fight six weeks out.

UFC Fight Night, September 26. Kalshi does not list the card; Polymarket does, as individual moneylines.

Barcelos vs Rosas Jr. is the busiest at $1,133. Simon vs Montel is $283, Hiestand vs Nakamura $105, Dumont vs Perez $60. Five fights, $1,609 in total—less than a thousandth of what last night's settled card moved while nobody could change the outcome.

UFC 331, September 19. Pantoja beat Van and the contract is marked 0.1%. It has taken $2,134,357 since. Four more fights from the same card cleared $150,000 each, all of them decided.

Trump did not attend UFC 331. The contract is marked 1% against $257,531 of open interest and settles at 14:00 today—still more standing paper than the entire September 26 card. Beside it, Polymarket's middleweight title board for the end of 2026.

Canelo vs Mbilli settles November 1, Sandoval vs Collazo October 11, and the UFC Fight Night card on September 27. The Trump attendance contract settles at 14:00 today.

Three things to watch:

• Whether the settled contracts keep trading. $2.13m through a leg marked at a tenth of a percent, on a fight that finished, is the largest single-contract flow in this catalog and nothing about it is a forecast.
• The three-point spread between the two boxing books. Canelo–Mbilli sums to 103 and Sandoval–Collazo to 97, five weeks apart on the same exchange.
• Whether the September 26 card ever trades. $1,609 across five fights, a week out, on a venue that moved $3.5m on last night's card after it ended.