Polymarket US: Arbitrage on the Regulated Exchange
← Blog July 30, 2026

Polymarket US: Arbitrage on the Regulated Exchange

Polymarket now runs a CFTC-regulated US exchange. That gives the United States a second regulated venue for event contracts alongside Kalshi, and two venues pricing the same events independently is where arbitrage lives.

TL;DR

Polymarket US is the CFTC-regulated US exchange operated by QCX LLC, the entity Polymarket built after acquiring the licensed derivatives venue QCEX in 2025. It lists fully-collateralized event contracts, no margin, no borrowed money. Because it prices the same sports, politics, and macro events as Kalshi, another CFTC-regulated US venue, the same contract can trade at a different implied probability on each. That gap is an arbitrage. Claw Arbs ships with Polymarket US as a pre-installed venue and can detect and fire both legs automatically.

What Is Polymarket US?

Polymarket US is the US-regulated arm of Polymarket. In July 2025, Polymarket acquired QCEX, a CFTC-licensed derivatives exchange, for about $112 million. The US entity, QCX LLC, does business as "Polymarket US" and operates as a CFTC-regulated Designated Contract Market (DCM), the same category of federal oversight that covers Kalshi and traditional futures exchanges like the CME.

Polymarket re-entered the US market in late 2025. In November 2025 the CFTC issued an Amended Order of Designation that permits an intermediated US trading platform. By 2026, US users can trade fully-collateralized event contracts on Polymarket US: no margin, no borrowed money, every position backed dollar for dollar. When you buy a contract, the cash to cover it is posted up front, and there is no borrowed exposure sitting behind your position.

That structure matters for traders. It makes Polymarket US behave like a cash-settled event exchange rather than a margin-based derivatives desk. What you see is what you own.

This is a separate thing from the global Polymarket order book that has run on the Polygon blockchain for years. The offshore book still exists and still serves international users. Polymarket US is the domestic, CFTC-regulated venue that now sits alongside it. Keeping those two straight is the first step to understanding where the edges are.

Is Polymarket US Legal to Trade?

Short version: Polymarket US operates as a CFTC-regulated Designated Contract Market, so it sits inside the US federal framework for event contracts, structurally similar to Kalshi. The deeper regulatory history, the state-by-state nuance, the earlier enforcement action against the old offshore book, and the tax treatment are all covered in our full guide on whether is Polymarket legal in the US. This post assumes you have settled the legal question and focuses on the trading opportunity Polymarket US creates.

Polymarket US vs Kalshi vs Offshore Polymarket

Three venues, three different structures. Understanding how they differ is what lets you see the arbitrage in the first place.

Venue Regulator Collateral Who Can Trade Arb Role
Polymarket US CFTC (DCM, via QCX LLC) Fully collateralized, dollar for dollar US users New US-regulated book, prices independently
Kalshi CFTC (DCM) USD, fully collateralized US users Established US-regulated book
Offshore Polymarket None (offshore, decentralized) USDC on Polygon Global users Global book, diverges from US pricing

Two of those three are CFTC-regulated US venues: Polymarket US and Kalshi. They list overlapping events. They set prices independently. The third, offshore Polymarket, prices in USDC for a global crowd. Every pairing is a potential source of edge, and Polymarket US is the piece that was missing until now.

Why Polymarket US Opens a New Arbitrage Edge

Arbitrage means buying opposite sides of the same event on two venues so the combined cost is under $1.00. Whichever way the event resolves, one side pays $1.00, and the difference is locked-in profit before fees.

For years, the cleanest cross-venue prediction-market arb available to US traders was Kalshi against offshore Polymarket, which our Kalshi vs Polymarket arbitrage guide walks through in detail. That trade always carried a wrinkle: one leg was a US-regulated exchange and the other was an offshore crypto book, with capital parked in USDC on Polygon.

Polymarket US changes the picture. Now there are two CFTC-regulated US venues listing the same sports, politics, and macro events. When Polymarket US and Kalshi both list "Will Team A beat Team B tonight?", they price it independently, off separate order books fed by separate user bases. Independent pricing means the two implied probabilities rarely line up to the cent. When they diverge far enough that YES on one plus NO on the other costs less than $1.00 after fees, that gap is a locked arbitrage.

The forces that create the gap are structural, not random:

These are the same frictions that keep Kalshi and offshore Polymarket out of sync, now reproduced between two domestic books. The difference is that with Polymarket US, both legs sit inside the US-regulated framework.

A Worked Polymarket US Arbitrage Example

Here is an illustrative example. The numbers below are made up to show the mechanics; they are not live prices, and real edges are usually thinner and shorter-lived.

Say an NBA game, Lakers vs Celtics, is listed on both venues. Polymarket US prices Lakers YES at $0.54. Kalshi is a touch more bullish on the Lakers and prices their YES at $0.57, which puts the Kalshi NO (Lakers do not win) at $0.43.

Walk both outcomes:

Either way, the pair returns about 3.1% gross before fees. That is the shape of a Polymarket US arbitrage: a locked spread with no directional risk on the outcome. The catch is that fees and slippage decide whether it clears. Kalshi charges a fee on winnings (a 7% default tier), so on a 3% gross edge the fee can swallow most or all of the margin unless you are on a lower tier or the gap is wider. Our prediction market arbitrage guide covers the fee-adjusted edge math in full, and the arbitrage betting calculator lets you model any pair of prices. Outcomes are never guaranteed: thin books can move before both legs fill, and a market can resolve in a way you did not model.

The Second Edge: Polymarket US vs Offshore Polymarket

There is a second, quieter edge. Polymarket US and the offshore Polymarket book are separate order books serving separate audiences under separate rules. The same market can carry a different price on the US-regulated book than on the global book. US-regulated flow and global crypto flow do not always agree, and there is no instant mechanism forcing the two prices together.

So the same "Will X happen?" contract might read 54c on Polymarket US and 51c on the offshore book. That three-cent gap, if it survives fees and the practicalities of holding capital on both sides, is another arbitrage. It is the classic US-regulated-versus-global divergence, except now both books carry the Polymarket name.

For a trader running a full stack, that means Polymarket US adds edges in two directions at once: against Kalshi (US versus US) and against offshore Polymarket (US versus global). One new venue, two new sets of gaps.

Why Prediction Markets Stay Arbitrage-Friendly

One structural advantage sits underneath all of this. Prediction markets do not limit winning traders the way sportsbooks do. A sharp sportsbook that catches you beating its lines will cut your stakes or close your account. Exchanges like Polymarket US and Kalshi are venues, not counterparties: they match buyers with sellers and take a fee, so a consistently profitable trader is a good customer, not a threat to the house.

That is why a cross-venue strategy between Polymarket US and Kalshi can compound over time. You are not racing a limit clock or hiding your activity. The real constraint is finding the gaps fast enough and clearing both legs before they close, which is an infrastructure problem, not an account-survival problem. Our Polymarket value betting guide covers the same structural edge from the single-venue mispricing angle.

Trading Polymarket US With Claw Arbs

Manually watching two order books for sub-second gaps is not realistic. By the time you have checked Polymarket US and cross-referenced Kalshi by hand, the window is gone.

Claw Arbs now ships with Polymarket US as a pre-installed venue, the twelfth, sitting in the prediction-market group right next to Kalshi and Polymarket, alongside Predict.fun, SX Bet, and the sharp sportsbooks. It connects to Polymarket US via API as a regulated exchange, streams prices in real time, and compares them against every other venue in the stack.

When a gap opens between Polymarket US and another book, the engine detects it and can execute both legs automatically in roughly 20 milliseconds. Every candidate trade runs through a 14-step safety pipeline: freshness checks, minimum and maximum edge bounds, depth checks, cooldowns, and a naked-leg guard that halts new trades on a match the moment one leg fills without its hedge. You can run the whole thing in paper trading first, watching Polymarket US edges fire against simulated fills before you commit real capital.

Claw Arbs is free during the current testing period and already has more than 1,000 users. You can watch real Polymarket US and Kalshi edges stream on the live arbitrage board as the engine detects them, or download Claw Arbs and run it yourself.

Risks to Keep in Mind

Polymarket US arbitrage is locked in theory, not in practice. The real risks:

Prediction-market trading carries real risk and you can lose money. Nothing in this article is a profit promise, and every number in the worked example is illustrative rather than a live quote.

FAQ

What is Polymarket US?

Polymarket US is the CFTC-regulated US exchange operated by QCX LLC, the entity created after Polymarket acquired the licensed derivatives venue QCEX for about $112 million in 2025. It runs as a Designated Contract Market, the same category of federal oversight that covers Kalshi. US users can trade fully-collateralized event contracts on it, with no margin and no borrowed money, so every position is backed dollar for dollar.

Is Polymarket US the same as regular Polymarket?

No. Polymarket US is the domestic, CFTC-regulated venue operated by QCX LLC. The original Polymarket is a global order book that settles in USDC on the Polygon blockchain and serves international users. They share the Polymarket name but run as separate books with separate user bases, so the same event can trade at a different price on each one.

Can you arbitrage between Polymarket US and Kalshi?

Yes. Polymarket US and Kalshi are both CFTC-regulated US venues that list many of the same sports, politics, and macro events. Because they price those events independently off separate order books, the same contract can carry different implied probabilities on each. When buying YES on one and NO on the other costs less than one dollar after fees, the difference is a locked arbitrage. Edges are usually small and short-lived, and fees and slippage decide whether a trade clears.

Is trading on Polymarket US fully collateralized?

Yes. Polymarket US lists fully-collateralized event contracts with no margin and no borrowed money. Every position is backed dollar for dollar, so the cash to cover a contract is posted up front and there is no borrowed exposure behind it. That structure makes it behave like a cash-settled event exchange rather than a margin-based derivatives desk.

The Bottom Line

Polymarket US turns a one-sided US prediction-market scene into a two-venue one. A second CFTC-regulated exchange listing the same events as Kalshi means independent pricing, and independent pricing means gaps. Add the divergence between Polymarket US and the offshore book, and a full stack now has edges running in two directions at once. Those edges are real but modest and fleeting, so whether you capture them comes down to speed, cost control, and disciplined both-leg execution. That is exactly the problem Claw Arbs is built to solve.

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