01
The news
The fight over who regulates sports contracts played out in the CFTC's rulebook and Supreme Court briefs; Kalshi examined bets on Trump's press secretary pick.
$1.8B
Traded on NFL games on the season's first Sunday, the league says
Over half of the $3.3B traded on prediction markets that day, the NFL told the Supreme Court, arguing that states should regulate the contracts as gambling.
Regulation · Fri, Oct 9
CFTC proposes defining sports, political and other event contracts as swaps
Swap status would back the CFTC's claim to oversee the contracts instead of the states; a same-day interim rule says sportsbook and casino bets are not swaps.
CFTC · CFTC · SBC Americas
Regulation · Thu, Oct 8
NFL and 39 states urge Supreme Court to hear New Jersey's case against Kalshi
The NFL says its games drew $1.8B of the $3.3B traded on prediction markets on the season's first Sunday; tribes and casinos also filed, and Kalshi must respond by Nov 9.
Supreme Court · Decrypt · CNBC · SBC Americas
Market integrity · Fri, Oct 9
Kalshi examines small bets placed before Trump's press secretary pick was reported
Three bets of about $19, $74 and $80 backed Katie Zacharia when her contract was priced near 1%, CNN reported; they stood to net thousands of dollars.
Markets and the economy · Thu, Oct 8
Flávio Bolsonaro leads Lula 49% to 45% in first Datafolha poll for Brazil's runoff
A technical tie within the 2-point margin; Polymarket's price for a Lula win slipped from 15.5% to 12.5% over the week before the Oct 25 runoff.
Regulation · Thu, Oct 8
Interactive Brokers Canada says prediction markets are not gambling
The dealer, which offers Kalshi contracts to Canadians, is pushing back on lottery corporations that call the contracts gambling and want provinces to regulate them.
New exchanges and products · Wed, Oct 7
Four more tribes launch prediction market apps built on Kalshi's exchange
Each tribe owns its app while Kalshi matches and clears the trades; many tribes oppose the industry, and 145 tribes and tribal groups backed New Jersey at the Supreme Court.
Culture and publicity · Thu, Oct 8
Ronald Acuña Jr. becomes the first MLB player to sign with a prediction market
His Kalshi ad aired during the Braves' NLDS Game 4 loss to the Dodgers; Kalshi already partners with five MLB clubs and is reportedly in talks with the league.
Market integrity · Fri, Oct 9
NBA's Adam Silver says the league wants prediction market data to spot manipulation
He wants a say over which contracts list and backed the NFL's call for a trading age of 21, but favoured one national policy over rules from about 40 jurisdictions.
02
The money
Traders paid $4.93B for contracts on the venues tracked, down 0.3% on the week before; Kalshi led with $3.53B, flat at a 12-week high ($19.0B at $1 payout).
Twelve weeks of volume, exchange by exchange
July 20 to 26, 2026
$0
Dollars paid for contracts each week, from DefiLlama. Exchanges often quote notional volume, which counts every contract at $1 and is larger.
Who had the week
- Kalshi72%$3.5B
- Polymarket10%$494.8M
- Polymarket US14%$688.1M
- Opinion1%$64.3M
- Others3%$146.5M
Day by day
Every exchange this week
| Exchange | Volume | vs last week | Share | Open interest |
|---|---|---|---|---|
| Kalshi | $3.5B | ±0% | 72% | $1.8B |
| Polymarket US | $688.1M | −1% | 14% | $209.6M |
| Polymarket | $494.8M | −4% | 10% | $343.2M |
| Predict.fun | $80.5M | +7% | 2% | — |
| Opinion | $64.3M | −10% | 1% | $3.2M |
| PredictStreet | $17M | +98% | 0% | — |
| MagicMarkets | $14.4M | +19% | 0% | — |
| XO Market | $12.4M | −12% | 0% | — |
| TurboFlow Prediction Markets | $9.9M | −7% | 0% | — |
| Polymarket Combos | $5.1M | +9% | 0% | — |
| world | $2.6M | +4% | 0% | — |
| PancakeSwap Prediction | $1.9M | +5% | 0% | — |
| Overtime | $1.6M | −19% | 0% | — |
| Sport.fun | $1M | +7% | 0% | — |
03
The markets
Kalshi traders had the Cowboys at 83% before the Buccaneers won; Lula slid from 15.5% to 12.5% before Brazil's runoff, and Kane rose from 47% to 66% for the Ballon d'Or.
Where the money went
Polymarket
Each bubble is a market, sized by what traded on it this week. Kalshi counts contracts at $1 and Polymarket the dollars paid, so compare sizes within each exchange.
What moved
Lula wins Brazil
from 16% at the start of the week
The market we noted last week slid again, from 15.5% to 12.5%, as Datafolha put Flávio Bolsonaro ahead 49% to 45% for the Oct 25 runoff
Cowboys beat Buccaneers
from 83% at the start of the week
Dallas started the week at 83%; the Buccaneers won 24–16 there, giving rookie quarterback Jalon Daniels his first NFL win
Giants beat Commanders
from 37% at the start of the week
Ended the week at 50%, up from 37%, after the Giants and Commanders tied 27–27 in overtime
Social Reckoning RT above 75
from 36% at the start of the week
Fell from 36% to 1% as reviews of Aaron Sorkin's Facebook film came in, putting it near 60% on Rotten Tomatoes
KT beat Vitality in game 2
from 49% at the start of the week
Thunder beat Hawks
from 55% at the start of the week
04
Called it?
What each market paid for the outcome as the week began, and what happened.
Ringed: an upset. Point at a dot for the market.
05
Your call
Guess the odds, then see what traders are paying.
Kalshi
US inflation above 3.6% in Sept
You: 50%
Kalshi
Barcelona beat Galatasaray
You: 50%
06
The winners
joseph00677 topped Polymarket's weekly profit board with $1.6M on $9.9M traded; BreakTheBank made $700K on the 49ers' win in Seattle and $416K on Eagles–Jaguars.
Most profit this week
- 4Papeasy+$609.2K
- 53edmond.dantes+$479.3K
- 6omnibus-076daa+$473.7K
- 7Bigggggggg+$386.1K
- 8Ancient-Strike+$380.8K
Biggest single wins
- +$1.2M
joseph00677 staked $1.4M, collected $2.6M
Diabolical-Prize staked $1.3M, collected $2.2M
- +$700K
BreakTheBank staked $735.8K, collected $1.4M
- +$416K
BreakTheBank staked $384K, collected $800K
- +$402K
joseph00677 staked $1.6M, collected $2M
- +$372K
Sassy-Bucket staked $228K, collected $600K
Polymarket's public leaderboard over the seven days to collection. Names are the ones traders chose.
07
On VPX
In play money that can't be cashed out, 6 traders made 19 trades worth T$19K, down from T$125K; the top market, a Bank of Canada hold in October, drew T$7.3K.
- T$19K
- traded, −85% on the week before
- 6
- traders
- 19
- fills
- 4
- new members
- T$747.8K
- on offer in the order books
- 265
- open markets
Volume by week, T$
Busiest on VPX
- Bank of Canada Decision in October?: No ChangeT$7,300 · 91%
- Vancouver Mayoral Election Winner: Ken SimT$5,300 · 40%
- Vancouver Mayoral Election Winner: Pete FryT$2,100 · 58%
- US-Canada diplomatic agreement to lower tariffs by...?: December 31T$1,100 · 40%
- Will US Strike Cuba in 2026?T$1,060 · 1%
08
The week ahead
US inflation on Oct 14, Vancouver's election on Oct 17, Brazil's runoff on Oct 25, the Ballon d'Or on Oct 26, the Fed and Bank of Canada on Oct 28 and the midterms on Nov 3.