2026 Seoul Mayoral Election: Margin of Victory

Platform comparison

Active sub-markets

Market context

Seoul will hold its mayoral election on 3 June 2026, with voters selecting the city's chief executive for a four-year term. The margin of victory—calculated as the percentage-point gap between the top two finishers—determines the resolution of this market. A candidate winning by 5 percentage points, for instance, would resolve differently from one winning by 15 points, making the granularity of the outcome material for conditional orders and algorithmic position-sizing.

Historical Seoul mayoral contests show substantial variation in decisive margins. Park Won-soon's 2014 victory came with a 16.7-point margin over his nearest rival, whilst Oh Se-hoon's 2018 win narrowed to 10.2 points amid fragmented opposition. The 2022 election saw Oh Se-hoon secure re-election by 6.7 points in a tighter three-way race. These precedents suggest margins typically range between 6 and 17 percentage points when a single dominant candidate emerges, though closer contests remain possible if the ruling and opposition parties field competitive nominees without significant defections.

Traders should monitor South Korea's political calendar and party primary schedules throughout 2025 and early 2026. The Democratic Party and People Power Party candidate selections—likely occurring in late 2025—will shape the competitive landscape. Approval ratings for President Yoon Suk Yeol and Seoul's incumbent administration, reported monthly by Gallup Korea and Realmeter, function as leading indicators for turnout and baseline support. Any major policy announcements, corruption allegations, or shifts in national politics between now and June 2026 could compress or expand expected margins, making real-time news feeds and polling aggregators essential inputs for dynamic hedging strategies.

Methodology

This page is a comparison snapshot: one live quote (Polymarket), four reference venues with their key attributes, and a single execution path — every trade button routes to Polymarket App UK, which mirrors the Polymarket order book directly.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket App 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?

Polymarket App 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.

What does it cost to trade on Polymarket App UK?

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