Lawyers have warned South Koreans who trade contracts on prediction markets could face prosecution under gambling laws, after a Polymarket user won $160,000 on the outcome of the Seoul mayoral election.
The user made a 106.41% profit on their stake after backing the incumbent Oh Se-hoon ahead of the June 3 election.
Oh, of the conservative, opposition People Power Party, was a massive underdog going into the election. His closest rival, the Democratic Party’s Chong Won-oh, had led Oh consistently in opinion polls coming into the June 3 vote.
An exit poll conducted by the national broadcast networks KBS, MBC, and SBS forecasted Chong to win with over 51% of the vote, with Oh more than 5 percentage points behind.
Early counting saw Chong lead for several hours, before late counting saw Oh surge ahead with minutes left, winning by just under 1%.
The win was a major upset, with the centrist Democratic Party sweeping all but four of the 16 mayoral seats up for grabs.
In usually conservative and pro-PPP Busan, Democratic Party candidate Chun Jae-soo defeated his PPP rival, the incumbent Mayor Park Heong-joon.
The same Polymarket user, JackinT, backed Chun to win, losing $16,000.
Prediction Markets: Could South Korean Courts Prosecute Users?
Unnamed legal experts told the South Korean newspaper Joongang Ilbo that South Koreans who place bets on platforms like Polymarket may be charged with gambling offenses under the terms of the Criminal Act.
If convicted, lawyers said, they could face fines of up to 10 million won (around $6,500).
South Korean law forbids residents from placing bets in overseas casinos, both land-based and online. However, to secure a conviction, prosecutors would need to prove that prediction market-related activity constitutes gambling.
JackinT also scooped almost $4,000 by backing other mayoral and gubernatorial candidates with smaller trades.
The same user also won money by buying “no” contracts for the prediction “Will Chong Won-oh win the 2026 Seoul Mayoral Election?”
JackinT’s win saw the user rise to No. 36 on the Polymarket monthly leaderboard. The user appears to be new to Polymarket, with data showing they have held only 6 positions to date.
Local Election Candidate Rides Gambling Accusation Storm
Gambling-related controversies dogged many political candidates ahead of the June 3 poll.
Last month, campaigning in South Jeolla Province and Gwangju saw candidates enter into a gambling-themed fracas.
During a live TV debate, a rival candidate accused Kim Dae-jung, the province’s incumbent education superintendent, of “loitering around a gambling den” during a state-sponsored business trip.
Kim later admitted to visiting a casino at the hotel where he was staying during a work-related visit to Vietnam. Kim, however, denied gambling at the casino.
The controversy failed to derail Kim’s election bid, however, with the incumbent winning comfortably. Turnout in the province, however, plummeted to just over 53%.
Gambling-related controversy also continues to rage in the world of South Korean pro sports. Four baseball players from the Busan-based Lotte Giants franchise recently returned from suspension after they were caught placing bets in a Taiwanese gambling den.
