Polymarket bettor shares in Oh Se-hoon's unexpected success, pocketing more than $160,000 from wager

A bettor on blockchain-based prediction platform Polymarket has reportedly pocketed roughly $160,000 from a wager on Seoul Mayor Oh Se-hoon’s victory in local elections on Wednesday.

A user operating under the nickname “JackInT” placed large wagers on several key battleground regions ahead of local elections, including the cities of Seoul and Busan as well as South Gyeongsang, according to Polymarket.

The user’s total investment reached $321,500, and the account showed profits of $97,863 over the past 24 hours alone.

Their biggest windfall came from the Seoul mayoral race. The bettor earned $160,102 by wagering on the prediction contract bid that Oh Se-hoon of the opposition People Power Party (PPP) would win the election.

The trade generated a 106.41 percent return, more than doubling their initial stake.

The user also earned an additional $3,828 by selecting “No” on another market that asked whether candidate Chong Won-o of the ruling Democratic Party (DP) would win.

The outsize returns appear to have been driven by pre-election polling that showed Oh trailing his rival Chong, which led markets to assign him relatively low odds of victory.

With traders giving Oh a lower chance to succeed, a winning bet offered a much larger payout. When the election result ultimately reversed market expectations, the bettor reaped a sizable profit.

In the South Gyeongsang gubernatorial race, the bettor posted a smaller gain after backing Park Wan-soo of the PPP. 

The user’s prediction missed the mark in the Busan mayoral race, however. The user lost about $10,000 after backing Park Heong-joon from the PPP.

Additional losses on wagers tied to DP’s Chun Jae-soo, who was elected Busan mayor, pushed the bettor's total losses in the race to nearly $16,000. The user had bet on Chun’s defeat.

Polymarket is the world’s largest U.S-based decentralized prediction market platform. It allows users to trade cryptocurrency-based contracts tied to the outcomes of future events ranging from politics and sports to the economy and weather. Transaction records are publicly visible as it operates on blockchain technology.

The platform has recently strengthened its monitoring systems for suspicious trading activity in an effort to prevent illicit betting based on nonpublic or insider information.

Yet Koreans may face legal concerns for using overseas prediction markets. Under domestic law, most online betting is considered illegal gambling except for a limited number of legally sanctioned products, such as Sports Toto.

Legal experts say Koreans who participate in overseas prediction markets such as Polymarket for financial gain could be subject to prosecution under provisions governing gambling in the Criminal Act. A conviction can carry a fine of up to 10 million won.

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.

BY JEONG JAE-HONG [[email protected]]