NEWS & LEARNING · REGULATION
Kalshi posted its biggest week yet in early October, helped by football contracts, while 40 state attorneys general urged the Supreme Court to decide who regulates sports event contracts.
- Record week: Kalshi reported $19.03 billion in contract volume for Oct. 5-11
- Football: $1.5 billion in standalone Kalshi football trading that week
- Legal pressure: 40 state attorneys general backed New Jersey's request for a Supreme Court ruling
Prediction markets had their biggest week yet in early October, and football was a big reason why. Kalshi reported more than $19 billion in contract volume for the week of October 5 to 11, its highest weekly total so far, while industry trackers counted more than $10 billion traded across exchanges on a single weekend.
The surge comes as the legal fight over sports event contracts intensifies. Kalshi is in court with 21 states, 40 state attorneys general have asked the US Supreme Court to decide whether federal commodities law overrides state gambling laws, and some states have moved from civil suits to criminal charges.
Here is what the latest numbers show, where the legal battle stands, and what it means for bettors who use both sportsbooks and prediction markets.
The Numbers Behind the Boom
Prediction market volume is reported in several different ways, which makes headline figures easy to misread. Here is what the main trackers reported for the week of October 5 to 11:
| Platform | Reported volume | Measure |
|---|---|---|
| Kalshi | $19.03 billion | Contract volume |
| Polymarket US | About $2.8 billion | Trade volume |
| DraftKings Predictions | $734 million | Weekly volume |
| Novig | $672 million | Weekly volume |
| Industry total | $25.6 billion | All tracked exchanges |
Figures from DeFi Rate and The PM Pulse with Aldrin Research, as reported by Sportsbook Review.
Kalshi's weekly contract volume has risen about 60% in six weeks, from $11.86 billion in the week ending September 6. Polymarket US nearly tripled over the same period. Sunday, October 11, was Kalshi's busiest day of the week at $4.20 billion.
How Much of That Is Sports?
The answer depends on how you count. The PM Pulse reported $1.5 billion in standalone Kalshi football trading for the week, up 12% from the prior week, and $3.8 billion across all sports. DeFi Rate's labeled sports subset came to $3.76 billion, about 20% of Kalshi's weekly total.
That leaves a huge share of volume in combo contracts, the prediction market equivalent of parlays. Combos accounted for 65.3% of Kalshi's weekly volume, about $12.4 billion, and drove more than 71% of the industry's week-over-week growth. Many of those combos involve sports outcomes, which means sports likely make up a much larger share of real activity than the standalone figures suggest.
Why the Headline Numbers Need Context
Trackers are careful to note that these are notional figures. Contract volume is often measured at face value, which can be many times larger than the money customers actually put at risk. It is not the same as sportsbook handle, and it is not revenue. Comparing Kalshi's $19 billion week directly with New York's roughly $600 million in weekly sportsbook handle would be misleading.
Even with that caveat, the growth is real. Macquarie projects 2026 industry taker volume of about $187 billion, compared with about $22 billion in 2025.
Where the Legal Fight Stands
The legal picture changes almost weekly, but as of mid-October, here is the broad shape of the fight.
The Federal Argument
Kalshi and its supporters argue that event contracts are federally regulated derivatives under the Commodity Futures Trading Commission (CFTC), and that state gambling laws do not apply. The CFTC has backed that position, filing suits or motions against several states, including Arizona, Connecticut, Illinois, New York, Rhode Island and Wisconsin. It has won a temporary restraining order in Arizona and a federal injunction in Tennessee.
The State Argument
States argue that sports contracts are simply sports betting under another name, and that they should be licensed and taxed like sportsbooks. Kalshi is now in court with 21 states. Arizona has filed criminal charges against the company, and Ohio fined Kalshi $5 million, a penalty upheld by a lower court.
The Supreme Court Question
New Jersey has asked the US Supreme Court to decide which body regulates sports event contracts, and 40 state attorneys general filed an amicus brief urging the court to take the case. Connecticut and Illinois cases are also expected to reach the Supreme Court. Until the justices rule, the patchwork will continue.
State-by-State: Where Sports Contracts Are Available
Based on CBS Sports' tracker, updated October 16, availability varies widely:
| Status | Examples |
|---|---|
| Not live | Michigan, Nevada, Utah |
| Partially available | Arizona, Connecticut, Maryland, Tennessee |
| Live but contested | California, Illinois, New York, Ohio, Rhode Island, Texas, Wisconsin |
| Ban blocked by court | Minnesota |
| Operating again after a brief ban | New Jersey |
Some states, such as Massachusetts and Washington, are listed with conflicting status in the tracker, which shows how quickly rulings are changing. Always check your state's current status before opening an account.
Tribal Gaming Concerns
Tribal nations have joined the fight. Three California tribes argue that prediction markets violate the Indian Gaming Regulatory Act; a federal judge denied their request for an injunction, and they have appealed to the Ninth Circuit. In Wisconsin, the Ho-Chunk Nation filed a federal suit arguing that prediction sites threaten authorized tribal gaming. Tribal gaming is a major part of the US gambling economy, so these cases could carry real weight.
Why Football Matters So Much
Football is the engine of US sports betting, and it is now the engine of prediction market growth too. Several factors explain the shift:
- Availability. In states without legal sportsbooks, such as California and Texas, prediction markets offer a way to trade on NFL outcomes.
- Pricing. Prediction markets charge fees rather than building a margin into the odds, which some traders see as a better deal.
- Combos. Multi-leg contracts mirror the popular same-game parlays offered by sportsbooks.
- Marketing. Prediction platforms have signed deals with athletes and sports teams, raising their profile, although those partnerships have sparked backlash from some fans who worry about the effect on the games.
The Concerns
Critics raise several issues:
- No state taxes. Prediction markets do not pay state gaming taxes, while licensed sportsbooks pay rates that have been rising in many states.
- Consumer protection. State gaming regulators require responsible gambling tools, age verification standards and dispute processes. Critics argue prediction markets may not offer the same protections.
- Long-shot losses. Reporting on trading patterns has highlighted how heavily users bet on long shots that lose the vast majority of the time.
- Election markets. Beyond sports, markets on the 2026 midterm elections have raised concerns. Twenty-three states fully ban election betting, according to data analyzed by Pew Research.
Converting Prediction Market Prices to American Odds
Because prediction markets quote prices in cents and sportsbooks quote American odds, comparing the two takes a quick conversion. A contract priced at 60 cents pays $1 if it wins, so you risk 60 cents to win 40 cents. That is the same as American odds of -150. A contract priced at 25 cents risks 25 cents to win 75 cents, the equivalent of +300.
| Contract price | Implied probability | American odds equivalent |
|---|---|---|
| 25 cents | 25% | +300 |
| 40 cents | 40% | +150 |
| 50 cents | 50% | +100 |
| 60 cents | 60% | -150 |
| 75 cents | 75% | -300 |
These conversions ignore trading fees, which prediction markets charge separately. Once you account for fees, the effective price is slightly worse than the table shows, so compare the full cost before deciding which platform offers the better deal.
What It Means for US Bettors
If you use prediction markets, sportsbooks or both, here is what to keep in mind:
- Know the rules where you live. Availability can change overnight with a court ruling.
- Understand the product. Prediction market contracts are priced in cents, from 1 to 99, rather than American odds. A 60-cent contract implies a 60% chance. Our American odds guide explains how to convert between the two.
- Compare prices. The same outcome may be priced differently on a sportsbook and a prediction market.
- Watch your protections. Licensed sportsbooks are overseen by state regulators. Prediction markets operate under federal commodities rules, which work differently.
- Set limits. Whichever platform you use, decide on a budget in advance.
Frequently Asked Questions
Are sports prediction markets legal?
Platforms like Kalshi operate under federal CFTC oversight, but many states dispute that they can offer sports contracts. Availability varies by state and is changing as courts rule.
How big are prediction markets compared with sportsbooks?
Kalshi reported more than $19 billion in contract volume in one October week, but that figure measures face value, not money at risk. It cannot be compared directly with sportsbook handle.
Do prediction markets pay state taxes?
No. Unlike licensed sportsbooks, prediction markets do not pay state gaming taxes, which is one of the main arguments states make against them.
Will the Supreme Court decide the issue?
New Jersey has asked the Supreme Court to decide who regulates sports event contracts, with support from 40 state attorneys general. The court has not yet said whether it will take the case.
How do I compare a prediction market price with sportsbook odds?
Treat the contract price as an implied probability. A 60-cent contract implies a 60% chance, equal to American odds of -150. Then add any trading fees and compare that cost with the sportsbook's price for the same outcome.
What are combo contracts?
Combo contracts combine several outcomes into a single trade, similar to a parlay. They made up about 65% of Kalshi's volume in the week of October 5 to 11.
Odds, figures and legal status change frequently and can differ between sportsbooks and states. This article is educational and is not betting advice.
21+. Gambling problem? Call or text 1-800-GAMBLER, or visit ncpgambling.org for free, confidential help.
Keep reading
- Prediction markets vs. sportsbooks: the Kalshi legal war
- NFL Kickoff 2026: prediction markets close the gap
- 2026 state-by-state legalization roundup
- How American odds work
Need a betting term refresher? See our betting glossary.