Stuttgart Open: Gauthier Onclin vs Fabian Marozsan

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Market context

The Stuttgart Open grass-court tournament will host a first-round match between Belgian player Gauthier Onclin and Hungarian Fabian Marozsan on 8 June 2026. In prediction markets, a YES share represents a bet that Onclin advances; a NO share bets on Marozsan's progression. The settlement window closes on 15 June, allowing a week for the match to conclude. Should either player withdraw, the match be cancelled, or no winner emerge within seven days, the market resolves to a 50-50 split rather than favouring either outcome.

The 100% probability assigned to YES currently reflects limited historical data on both players' grass-court form and head-to-head records. Onclin, ranked outside the top 200 for much of his career, has shown modest improvement on faster surfaces, whilst Marozsan remains relatively unknown in ATP circuits. Without prior meetings or substantial recent tournament results to anchor expectations, the market may be responding to seeding announcements or late entry confirmations rather than established performance differentials. Comparable early-round grass matches involving lower-ranked players typically show wider probability spreads once draw sheets are published.

Traders should monitor official ATP and Stuttgart Open announcements for final draw confirmation, player injury updates, and any weather-related scheduling changes. Grass-court tournaments are particularly susceptible to rain delays; the settlement terms allow seven days for completion, but extended postponements could trigger the 50-50 resolution. Recent form on grass during warm-up events in May 2026 will provide the most reliable signal for adjusting the current extreme probability before match day.

Methodology

We track Stuttgart Open: Gauthier Onclin vs Fabian Marozsan 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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Is this market available outside the US?

Prediction Market 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's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

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.