SiaPredict DailySeptember 23, 2026
Top line
The CFTC issued a staff advisory flagging "mention market" contracts as presumptively susceptible to manipulation and, a day later, opened a review of unusual trading in Kalshi's ether perpetual futures market that could lead to a formal enforcement probe. Litigation activity also picked up, with Mexico's soccer federation suing Kalshi over Liga MX trademark use and Kalshi asking the Seventh Circuit to hear an interlocutory appeal in its tribal-sovereignty case. Underneath the regulatory news, Bernstein raised its long-run volume forecast for the industry to $10 trillion a year by 2035, even as a Wall Street Journal report on a $10 million fraud attempt against Polymarket underscored the operational risk that growth still carries.
Today's top 7
- 1Regulatory
CFTC staff advisory flags 'mention market' contracts as presumptively susceptible to manipulation
On September 22 the CFTC's Division of Market Oversight told designated contract markets that event contracts settling on a named person's words, attendance, or other discrete conduct are presumptively susceptible to manipulation under Core Principle 3, unlike election, economic-data, or independently scored sports contracts. The advisory does not ban the category but ends reliance on Part 40 self-certification for it, requiring exchanges to show upfront what constrains the person whose conduct decides the outcome and what surveillance and position limits apply. Kalshi is the primary operator of mention contracts and is named throughout the advisory's enforcement backdrop, so any DCM listing similar products now faces a materially higher bar before self-certifying.
The Block - 2Regulatory
CFTC weighs enforcement probe into Kalshi's ether perpetuals after $5 billion in near-identical trades
The CFTC is reviewing trading activity on Kalshi's ether perpetual futures market before deciding whether to open a formal enforcement investigation, after a Wall Street Journal analysis found nearly 1 million trades of near-identical size, more than a third clustered around $5,500 apiece and accounting for roughly $5 billion of ether-perp volume over the past month. Kalshi attributes the pattern to a single market maker holding fixed resting quotes that hundreds of distinct takers, including Jump Trading and Wintermute, repeatedly filled, and says self-trading is mechanically blocked on its exchange; no enforcement action has been filed. It is the CFTC's first look at possible manipulation in Kalshi's crypto-perpetuals line rather than its sports or political contracts, landing one day after the agency's mention-markets advisory.
Unchained - 3Regulatory
Mexico's soccer federation sues Kalshi over Liga MX trademark and data use
Mexico's soccer federation, FMF, sued Kalshi in the Southern District of New York on September 22, alleging Kalshi used the LIGA MX trademark and club names on its sports event-contract pages, and designated FMF-produced match data as the determining facts for those markets, without FMF's permission and after repeated cease-and-desist demands. FMF seeks a TRO plus preliminary and permanent injunctions barring the trademark and data use, along with damages tied to Kalshi's profits on the affected markets. Kalshi says its use was "limited to plain-text identification" within CFTC-regulated markets and denies infringement, but the case adds a data-licensing and IP front to Kalshi's litigation load alongside its jurisdictional and tribal-sovereignty fights.
Gambling Insider - 4Regulatory
Kalshi asks Seventh Circuit to hear interlocutory appeal in Ho-Chunk Nation tribal-sovereignty case
Kalshi petitioned the Seventh Circuit on September 22 to accept an interlocutory appeal of two questions Judge William Conley certified on September 11: whether violations of tribal gaming ordinances are actionable under IGRA against a non-signatory to the compact, and whether the CEA and UIGEA's DCM carve-out overrides IGRA on sports-event contracts. Kalshi argues the questions present issues of first impression in the Seventh Circuit, and that the Ninth Circuit's September 16 ruling for California tribes on a similar IGRA theory is not binding here since Wisconsin sits outside that circuit. The underlying case stays stayed pending the appeal, with a May 24, 2027 trial date still on the docket if it proceeds.
Law360 - 5Industry
Bernstein raises 2035 prediction-market volume forecast to $10 trillion as financial contracts overtake sports
In a September 22 client note, Bernstein raised its long-run forecast for industry-wide annual trading volume to $10 trillion by 2035, roughly ten times its prior 2030 estimate, projecting the category compounds at about 70% a year as financial-asset contracts, crypto, equities, and commodities, grow from 12% of volume in 2025 to 49% by 2035 while sports falls from 61% to 38%. The note puts Kalshi's current share of industry volume at about 60%, up from 35% a year ago, on the strength of its crypto-perpetuals build-out, while noting full US regulatory clarity for sports-linked contracts is unlikely before 2027 or 2028. Operators still weighted toward sports and politics, such as Polymarket, face a widening gap under this forecast unless their financial-contract lineup scales faster.
The Block - 6IndustryCatch-up
Polymarket faced $10 million stolen-card fraud scheme as compliance concerns mounted, WSJ reports
A Wall Street Journal report published September 20 found that fraudsters attempted to move at least $10 million through Polymarket's US platform earlier this year using stolen debit cards, exploiting weak payment and withdrawal controls only months after the platform began admitting American users; Polymarket's card processor rejected more than 80% of deposits at the peak of the scheme, against a roughly 1% fraud rate industry-wide. The report says CEO Shayne Coplan told staff to "keep growing and pay a fine" if regulators later objected, after compliance staff flagged the exposure. Polymarket has since capped the number of cards a user can link and says fraud rates are back near industry norms, but the account adds to a run of compliance-related reporting on the platform this month, including the FOIA-surfaced CFTC probes and a second influencer class action.
The Block - 7Industry
PredictIt drops withdrawal fees, moves to a profit-only fee structure
PredictIt eliminated its 5% withdrawal fee on September 23 and now charges traders only on profitable positions, while also offering one fee-free credit-card deposit per user up to $1,000. The change follows PredictIt's 2025 settlement with the CFTC that raised its old $850 single-contract cap to $3,500 and removed the 5,000-trader-per-market cap, and signals the smaller regulated operator competing on cost as Kalshi, Polymarket, and sportsbook-linked entrants scale up political and sports contract volume ahead of the 2026 midterms.
GlobeNewswire