South Korea built its Polymarket gambling case out of public blockchain records
Police referred 18 of 26 investigated users to prosecutors over 17.6 billion won in wagers, identifying them from on-chain transactions after regulators rejected the platform's argument that it had no Korean footprint.
The Investor · Invest desk
What happened
- South Korean police referred 18 Polymarket users to prosecutors in an illegal gambling investigation covering 26 people who wagered about 17.6 billion won, or roughly $12.7 million between them.
- Because Polymarket keeps no conventional real-name user list, police built the case by analysing publicly available blockchain transactions.
- The media and communications commission rejected Polymarket's argument that no Korean-language site, no won payments and noncustodial smart contracts placed it outside Korean law, and blocked access on August 18.
- Gangwon police opened South Korea's first illegal gambling probe into local Polymarket users in June, at the request of the National Police Agency.
Why it matters
- What it costs cost The block cuts Polymarket off from a pool TRM Labs sizes at about $69 billion of quarterly retail crypto volume, roughly a third of the US figure, and the exit was not the platform's choice.
- What it limits constraint Once a regulator holds that technical characteristics do not exempt a service, noncustodial design no longer places a platform outside Korean law, and blocking access in advance is the only step left to the operator.
- Who's exposed exposure The criminal risk falls on individual traders and concentrates sharply: one account is 32 percent of the wagered total, so the deterrent bites hardest on the heaviest users.
- What doesn't add up contradiction Cryptopolitan reads Korean enforcement as pulling liquidity toward regulated venues, but that measurement is missing from both reports, and the only available figures are sector aggregates.
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The structure Polymarket cited in its own defense is the structure that produced the evidence. It runs noncustodial and peer-to-peer with automated settlement, and there is no conventional list of users by real name [4]. Investigators read the public chain instead [3].
Polymarket told the commission there were no Korean-language services and no support for won payments, and that smart contracts meant it never directly managed user funds. The commission replied that technical characteristics did not exempt a service from South Korean law [10]. It pointed to the platform's role in operating the markets, setting trading rules, handling crypto deposits, withdrawals and settlement, and collecting transaction fees [6]. The winner-takes-all payout was cited as encouraging speculative gambling [6]. On the mechanics, the two sides are not far apart: a Tiger Research report describes the basic contract as paying $1 if the event occurs and $0 otherwise, with an oracle deciding after expiration [19].
Polymarket's geographic restrictions were updated on August 14 to exclude 39 countries, among them Japan, Singapore, Taiwan, Thailand and North Korea, with South Korea absent from both the fully blocked and the close-only list [17]. The access block came four days later [24].
The sums are small. Spread across 26 accounts, the roughly $12.7 million works out to about $488,000 each, and the single largest user at 5.7 billion won is 32 percent of the case on his own [20][15][2]. Against the $69 billion of retail crypto volume TRM Labs attributed to South Korea in its first-quarter 2026 index, the entire investigation is 0.018 percent of the flow [21]. What is being decided is the definition. Article 246 of the Criminal Act punishes gambling and Article 247 punishes running a gambling place, and the KMCSC invoked both, plus the National Sports Promotion Act, when it restricted access [12][8].
The two reports date the police step differently. Cryptopolitan says 26 users were charged on September 15 [7]. Cointelegraph describes them as under investigation as of Tuesday, citing Asia Economy on data the National Police Agency gave to lawmaker Yoon Kun-young [9].
Cryptopolitan's reading is that enforcement will not reduce demand. It will push platforms toward stricter geofencing instead, and move users and liquidity to jurisdictions that regulate them, with the CFTC's supervision of designated contract markets such as Kalshi as the contrast [26][14]. The migration goes unmeasured in both reports. The sector figures show how little capital would have to move: DeFiLlama puts $390 million locked against $4.4 billion of trading in seven days, about eleven times the locked value in a week, while Polymarket alone did $4 billion in a month [18][23].
I would expect the geofence, not the litigation, to settle this, and the way to know I am wrong is a Korean court taking the derivatives characterisation seriously. Tae-Lim Kim, managing attorney at AXIS Law, told Asia Economy that the transactions could meet the legal requirements for gambling. Calling them prediction derivatives, he said, would be difficult to use as a direct defense in criminal proceedings. The ability to trade contracts and exit positions before settlement could still be relevant to a court's assessment [16]. The users are making that argument anyway: they say Polymarket should be treated as a crypto-based derivatives investment market [11].
What to watch
- Whether prosecutors indict all 18 referred users, and on which statute, given that the commission invoked both the Criminal Act and the National Sports Promotion Act.
- Whether Polymarket's next update to its geographic restrictions adds South Korea to the fully blocked or close-only lists.
- Whether DeFiLlama's $390 million of prediction-market value locked starts showing up on CFTC-regulated venues instead.
Information, not investment advice. This story is general information about companies and markets, drawn from cited reporting. It is not a recommendation to buy, sell or hold any security; check the cited sources before acting.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence58
- Adoption64
- Hype gap+18
- Incentives45
- Confidence62
Perspective Coverage
3 publishers- Builder
- Builder 20%
- Operator
- Operator 47%
- Investor
- Investor 33%
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
South Korean police reportedly referred 18 Polymarket users to prosecutors in an illegal gambling investigation involving 26 people who collectively wagered about 17.6 billion won (worth $12.7 million).
- [2]
The largest amount wagered by a single user was about 5.7 billion won ($4.1 million).
- [3]
Police identified users by analyzing publicly available blockchain transactions.
- [4]
Polymarket operates on a noncustodial, peer-to-peer structure with automated settlement and does not maintain a conventional list of users by their real names.
- [5]
On Aug. 18, South Korean authorities moved to block Polymarket after determining that the prediction market provided an illegal gambling environment to users in the country.
- [6]
The country's media and communications review commission said the platform's winner-takes-all structure encouraged speculative gambling, citing Polymarket's role in operating markets, setting trading rules, providing crypto deposits, withdrawals and settlement, and collecting transaction fees.
- [7]
Cryptopolitan reported that South Korean law enforcement revealed 26 Polymarket users had been charged on September 15, with 18 referred to prosecutors.
- [8]
On August 18 the Korea Media and Communications Standards Commission decided to restrict access to Polymarket from South Korea, invoking provisions of the Criminal Act and the National Sports Promotion Act.
- [9]
According to Asia Economy, data submitted by the National Police Agency to the office of Democratic Party lawmaker Yoon Kun-young showed the Gangwon Provincial Police Agency had placed 26 people under investigation as of Tuesday and sent 18 of them to prosecutors.
- [10]
Polymarket argued it did not provide Korean-language services or support payments in Korean won, and that its noncustodial transactions and use of smart contracts meant it did not directly manage user funds; the commission rejected the argument, saying technical characteristics did not exempt a service from South Korean law.
- [11]
Authorities reportedly said Polymarket transactions constitute illegal gambling under South Korea's Criminal Act because users stake assets on outcomes that cannot be predicted with certainty; the users argued Polymarket should instead be treated as a crypto-based derivatives investment market.
- [12]
South Korea's Criminal Act punishes gambling under Article 246, while Article 247 addresses running a gambling place.
- [13]
TRM Labs ranked South Korea second in the world for retail crypto volume at approximately $69 billion, behind the United States at approximately $212 billion, in its Global Crypto Adoption Index for the first quarter of 2026.
- [14]
The US Commodity Futures Trading Commission regulates designated contract markets, including Kalshi.
- [15]
The single largest user's 5.7 billion won is about 32 percent of the 17.6 billion won wagered across the 26 accounts under investigation.
- [16]
Tae-Lim Kim, managing attorney at AXIS Law, told Asia Economy that the transactions could meet the legal requirements for gambling, and said describing them as prediction derivatives would be difficult to use as a direct defense in criminal proceedings, although the ability to trade contracts and exit positions before settlement could be relevant to a court's assessment.
- [17]
Polymarket's geographic restrictions, updated on August 14, exclude 39 countries from access, among them Japan, North Korea, Singapore, Taiwan and Thailand; South Korea does not appear on the fully blocked or close-only lists.
- [18]
DeFiLlama shows $390 million in value locked and $4.4 billion in seven-day trading volume for prediction markets; Polymarket saw $4 billion in trading volume in one month.
- [19]
According to a Tiger Research report, the basic prediction contract pays $1 if the event happens and $0 otherwise, so its price reflects the probability of the event occurring, with an oracle making the final decision after expiration.
- [20]
The roughly $12.7 million wagered across 26 accounts averages about $488,000 per account.
- [21]
The $12.7 million in the Korean Polymarket case equals about 0.018 percent of the $69 billion of South Korean retail crypto volume TRM Labs measured for the first quarter of 2026.
- [22]
South Korea's approximately $69 billion of retail crypto volume is about 33 percent of the approximately $212 billion recorded for the United States.
- [23]
Prediction markets' $4.4 billion of seven-day volume is about 11 times the $390 million of value locked in the same sector.
- [24]
South Korea's access block on August 18 came four days after Polymarket's August 14 update to its geographic restrictions.
- [25]
In June, Gangwon police launched South Korea's first illegal gambling probe into local Polymarket users at the request of the National Police Agency.
- [26]
Cryptopolitan wrote that more rigorous enforcement in South Korea may not diminish demand and could instead motivate platforms toward stricter geofencing and drive users and liquidity toward jurisdictions where they are more effectively regulated.
Sources
3 independent publishers whose own reporting we read for this story.
- cointelegraph.comPolymarket users referred to prosecutors in South Korea: Report
2 articles · September 17, 2026
- crowdfundinsider.comSouth Korea Refers Polymarket Users to Prosecutors Over Alleged Gambling Bets
1 article · September 17, 2026
- cryptopolitan.comSouth Korea blocks Polymarket as prediction markets face global split
1 article · September 17, 2026
Topics and entities
Entities
- Korean National Police Agency
- CFTC
- TRM Labs
- Korea Communications Standards Commission
- Tiger Research
- Polymarket
- DefiLlama
- Gangwon Provincial Police Agency
- Kalshi