UFC Fight Night: Karol Rosa vs. Luana Santos (Women's Bantamweight, Prelims)

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Active sub-markets

Market context

Polymarket is pricing the Karol Rosa vs. Luana Santos contract at **0% YES**, so the market is effectively treating a Rosa win as having no chance right now and is assigning all value to the other possible outcomes on the UFC’s official result. Because this is a USDC market on Polygon using conditional tokens, the settlement will hinge on the UFC’s declared result for the women’s bantamweight prelim, not on scorecards circulating on social media or sportsbook views.

That zero price is best read against the event context rather than as a statement that the fight is impossible to price. Tapology lists the matchup for UFC Fight Night, while the UFC has promoted Santos as a live contender and noted that a win over Rosa would push her towards the division’s top 10. Santos also weighed in at 136lb in pre-fight content, which is consistent with the bout being set to go ahead as scheduled. On comparable UFC fight markets, Polymarket prices near zero tend to appear when traders see a strong stylistic edge, a late replacement dynamic, or an informational lag before the official weigh-in and bout confirmation.

For traders, the main catalysts are simple: final UFC bout status, any late medical or commission changes, and whether the prelim actually starts before the settlement window closes. The key dependency is the official UFC result; if the contest is cancelled, postponed beyond the market’s cutoff, or ruled a no contest, the market can still resolve to 50-50 under the stated rules. In practice, the last meaningful move usually comes from the UFC’s weigh-in, cage-walk confirmation, and post-fight announcement rather than from unofficial live reporting.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track UFC Fight Night: Karol Rosa vs. Luana Santos (Women's Bantamweight, Prelims) on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Where can I trade this market with the lowest fees?

On Kalshi UK, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Kalshi UK is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What does it cost to trade on Kalshi UK?

Zero. Kalshi UK routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.