The same wager on different terms
Take one event, a football game, and one customer who wants to back the home team. At a licensed sportsbook the customer sees a price, say 1.91, accepts it, and the operator takes the other side. On an exchange the customer sees a yes contract at 52 cents, buys it from another customer, and the venue takes a fee. If the home team wins, both customers profit by about the same amount. The experiences are close enough that most customers do not notice the difference, and the differences are large enough that the entire industry is fighting over them.
This lesson lays the two side by side across the dimensions that matter to a customer, an operator and a state, and then asks what the customer is really choosing.
Price and cost
Covered in lesson two and summarised here. A sportsbook's cost to the customer is its margin, built into the price: about 4.5 per cent on a mainstream two-way market priced at 1.91 on each side, and more on props and parlays. Nevada's regulator reports the difference: in 2025 its sportsbooks kept 7.45 per cent of all sports wagers but 32.59 per cent of parlay-card wagers. An exchange's cost is a fee plus the spread the customer crosses. On Kalshi's general schedule the fee for taking a price is 7 per cent of the price multiplied by one minus the price, which peaks at 1.75 cents on a 50-cent contract, about 3.5 per cent of the contract's price; a resting order that is later filled pays a quarter of that on the sports markets. On liquid mainstream markets the exchange is usually cheaper, but for a customer who takes the price the saving is smaller than is often claimed. On niche markets the spread can exceed a bookmaker's margin, and the market may not exist.
The parlay is the sharpest illustration. A sportsbook's same-game parlay is its highest-margin product, priced by a correlation model the customer cannot see. An exchange lists single contracts; a customer who wants a parlay buys several and does the arithmetic. The regulated exchanges have begun to build combination products, and Kalshi now lists parlays, which it calls combos, but the pricing has to be found by the market rather than set by an engine, and it is where their offer is weakest.
Limits and welcome
A sportsbook manages its risk by managing its customers. Winners are limited, sometimes to trivial stakes, and the recreational majority subsidise the offer. Operator data given to Massachusetts regulators in 2024 showed only 0.64 per cent of accounts limited, but a direct link between winning and being limited, and since June 2026 Massachusetts has required sportsbooks to tell a limited customer within 48 hours and explain why. An exchange has no liability, so it has no reason to limit anyone. The sharpest bettors in the world are welcome, and their presence makes the price more accurate for everyone.
For a professional, that is decisive. For a recreational customer the picture is mixed. The price is better, but the person on the other side of the trade is more likely to be a professional than at a bookmaker, where the operator's margin is spread across a crowd. A recreational bettor at a sportsbook loses the margin; a recreational bettor on an exchange loses the margin and, sometimes, the trade.
Who can play, and where
In a regulated American state a sportsbook customer must usually be 21, physically present in the state and verified against the state's requirements: Pennsylvania's rules, for example, bar anyone under 21 and anyone outside the Commonwealth, and Kentucky, which had allowed 18, raised its minimum to 21 from 15 July 2026. A designated exchange's customer must have reached the age of majority in their state of residence, which in most states is 18, and is verified under the customer-identification rules of the USA PATRIOT Act, which are designed for financial accounts rather than gambling. The exchange's reach across the United States is now contested state by state: the Third Circuit ruled for Kalshi in New Jersey, but in August 2026 the Ninth Circuit held that Nevada could likely enforce its gaming laws against Kalshi's sports contracts, and in September the Sixth Circuit reached the same view for Ohio and Tennessee and a Michigan court ordered Kalshi to geofence the state.
Three years of age and the states without legal betting are the largest single difference in the two products' addressable markets. At the end of 2025 legal sports betting was offered in 39 states plus the District of Columbia, and only just over thirty of them had statewide online betting. A resident of California, Texas or Georgia, states without legal sports betting, cannot bet with a licensed sportsbook and can trade a sports contract on an exchange. The eleven states with no legal sports betting had about 111 million residents in 2025, about a third of the national population, and they are the reason the exchanges grew the way they did.
Tax and obligation
A licensed sportsbook pays a state gaming tax on revenue, at rates in 2025 from 6.75 per cent in Nevada and Iowa to 51 per cent on online betting in New York and a top rate of 52.25 per cent in Illinois (the state's 40 per cent top bracket plus county and Chicago city taxes on bets placed there), plus a federal excise tax of 0.25 per cent of each wager, plus licence fees, plus mandated contributions to responsible gambling programmes, plus the cost of a state-specific compliance function. An exchange pays ordinary corporate taxes but no state gaming tax on its event contracts. It funds no state programmes and answers to the CFTC rather than a state gaming regulator, although the courts are now divided on whether states can enforce their gaming laws against it.
The customer's tax position may also differ, because gambling winnings are taxed under their own rules: from the 2026 tax year a gambler can deduct only 90 per cent of gambling losses, and only up to the amount of gambling winnings. A state that has built a budget line on sports betting tax has a direct fiscal interest in the outcome of the litigation, which is why gaming regulators and attorneys general alike have fought it: in 2025 state and tribal governments in 16 states took action against prediction market platforms offering sports contracts.
Responsible gambling
A licensed operator is required to offer deposit limits, time limits, self-exclusion, affordability checks in some markets, staff trained to identify harm and a responsible gambling programme it funds and reports on. The requirements vary by state and are unevenly enforced, but they exist: in Pennsylvania, for example, a sportsbook's terms must set out the player's right to set responsible gaming limits, to self-exclude and to suspend the account for at least 72 hours. The industry's licence to operate rests on them.
The regulated exchanges have adopted some of the same tools, voluntarily and unevenly: self-exclusion, deposit limits, links to helplines. FanDuel Predicts, for example, launched with deposit limits, deposit alerts and self-exclusion. No gaming regulator requires these tools of an exchange or audits them, and the exchanges serve customers of 18 in states that have decided sports betting should be restricted to 21 or banned altogether. This is the argument on which the states are on strongest ground with the public, and the exchanges know it.
Product breadth and depth
A sportsbook offers thousands of markets a day across every sport, priced by an engine, settled by a team, available at any stake within the customer's limit. An exchange offers what its market makers will quote and its customers will trade, which is the main markets on the main events, plus a long tail of thin markets with wide spreads.
In the other direction, an exchange offers markets a sportsbook cannot: elections, economic data, court rulings, awards, weather, corporate events. Some of that is genuinely popular and some of it is a novelty, and sport dominates the volume: over 90 per cent of Kalshi's trades in 2025, representing 95 per cent of its revenue, were sports related. But it is a product range no gambling regulator in America would license, and it is the range that the "not gambling" argument was built to protect.
What the customer is actually choosing
Put the columns together and the choice looks like this. An exchange offers a better price, no limits, a lower age, wider access and a wider range of events, with thinner markets, weaker consumer protection and a counterparty who may be a professional. A sportsbook offers depth, parlays, promotions, a regulated environment and a recreational crowd, at a higher price, with limits, at 21, only in legal states.
For a professional the exchange wins. For a recreational customer in a legal state the sportsbook still has the better product, and the sportsbooks' parlays and promotions are aimed at that customer. For a customer in a state without legal betting, the exchange is the only onshore option, and that customer is the one the industry is fighting over.
Why the sportsbooks changed sides
Through 2025 the licensed industry's trade body, the American Gaming Association, campaigned against prediction markets offering sports betting outside state and tribal gaming law. By the end of the year the best-known sportsbook brands had moved in: DraftKings bought Railbird, a CFTC-designated exchange, in October 2025 and launched DraftKings Predictions in December, and FanDuel launched FanDuel Predicts with CME Group in December, offering sports contracts only in states where online sports betting is not yet legal. Nothing about the legal argument had changed in 2025. What had changed was the arithmetic: a product available in most of the country at 18 with no gaming tax had grown fast, in competition with one available online in about thirty states at 21 with a gaming tax, and the operators concluded that if the courts allowed it, they had better own it.
That is the commercial lesson of the comparison. The question for a licensed operator is not whether an exchange is better or worse than a sportsbook. It is whether the operator can offer both, hedge one against the other, and let the customer choose, before somebody else does.
What to take from this lesson
An exchange is cheaper, more open and more widely available; a sportsbook is deeper, more protective and more profitable per customer. The three-year age gap and the geography gap are the differences that matter to the market; the tax gap is the difference that matters to the states. The operators who spent a year fighting the product now sell it, because the arithmetic of an untaxed national product beat the argument against it.