The big winners Week 4 of the NFL Season included the Kansas City Chiefs, Minnesota Vikings and San Francisco 49ers -- all of whom ran their records to 4-0 - and traders who used Kalshi for their straight plays. And traditional books on parlays and combos.
Kalshi's Week 4 implied pricing stood at 4.28%, down from its season peak of 4.30% last week. Kalshi's single-market vig also beat FanDuel (4.41%) and DraftKings (4.47%).
The implementation of combo market-maker fees on Kalshi continued to impact pricing. Kalshi's implied vig on combos was 26.5%, slightly higher than last week and 327 basis points above the average of FanDuel and DraftKings.
The data, compiled by Jordan Bender of Citizens, focused on pricing at DraftKings and FanDuel — which control roughly 70% of the U.S. sports betting market — and Kalshi. It examined fees on straight bets and parlays/combos backing the favorite and the over in each of the NFL's 16 games as of Friday.
Kalshi offered sharper pricing than the two leading sportsbooks in Weeks 1 and 2 before FanDuel held a slight edge in Week 3.
Week 4 pricing stood at or below the season averages on all three platforms.
The takeaway: Kalshi offers the better value on single-game plays, while traditional books hold the edge on parlays/combos.
Books Continue To Hold Edge On Parlays/Combos
Parlay and combo pricing tells a different, less flattering story for Kalshi.
Averaging odds and implied vig on two combo constructions — the over, and the favorite — across every NFL game, Kalshi's combo implied vig was 26.5%.
Kalshi's new combo market-making fee, introduced in August has begun compressing spreads (and vig) as market makers adjust.
"We don't make markets on combos today. When we start quoting them, the new maker fees will force us and other makers to command a larger spread. Uncorrelated NFL combos are unchanged for now, but we're sure Kalshi will charge maker fees there too once there's enough competition," one market maker told Citizens last week.
So far, there's no sign of it hurting volume: Kalshi has 84% combo market share across US-licensed platforms over the last 30 days, compared to Polymarket (US) at 9% and 3% for DKeX (DraftKings).
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NFL Week 4 vs. Week 3 Implied Vig
Bender's data shows us that those players/traders who placed their straight plays on Kalshi fared slightly better in terms of the outright cost, while those who used traditional books got a better deal on multi-leg wagers.
Who Offers The Best Deal: Straight Bets
| Rank | Operator | Week 4 Vig | Week 3 Vig | Change |
|---|---|---|---|---|
| 1. | Kalshi | 4.28% | 4.38% | -10 bps |
| 2 | FanDuel | 4.41% | 4.37% | +4 bps |
| 3 | DraftKings | 4.47% | 4.52% | -5 bps |
Who Offers The Best Deal: Parlay/Combo
| Rank | Operator (Week 4) | Combo/Parlay Vig |
|---|---|---|
| 1 | Legacy sportsbooks (DraftKings / FanDuel avg.) | 23.2% |
| 2 | Kalshi | 26.5% |
The Takeaway
Prediction markets like Kalshi have pulled within range of traditional sports books -- but only for straight bets, not parlays.
- If you're betting moneylines or over/unders, Kalshi's "juice" (the cut the house takes, called vig) on par with FanDuel's and lower than DraftKings'.
- That's a reversal from last year: during the 2025 NFL season, Kalshi was actually more expensive than either sportsbook.
Why the shift happened: The theory is that as more money and more market-makers pour into Kalshi's markets, competition among liquidity providers pushes spreads down -- cheaper prices attract more volume, which attracts more liquidity providers, which pushes prices down further. A virtuous cycle, in the report's words.
Why this matters beyond your own bet: This data is also being used to argue that prediction markets aren't quietly killing traditional sportsbooks' business. Bender's analysis notes that any overlap between prediction-market and sportsbook customers isn't worsening, and may actually be growing the total pool of bettors rather than just moving them around -- which is why they expect sportsbook betting volume to pick back up later this year.
Data Source: Where The Numbers Come From
| Number | Source |
|---|---|
| Straight-bet vig comparison | Tracked pre-game pricing on moneylines and over/unders across FanDuel, DraftKings, and Kalshi — 28 data points collected Friday 10/2 afternoon, compared against full-season tracking from Week 1 of the NFL season |
| Combo/parlay vig comparison | Built by averaging Kalshi's odds on two bet types — the "over" and the favorite — across every NFL game (14 data points), then compared to standard parlay pricing at DraftKings/FanDuel |
| Kalshi's $1.62 average transaction fee (per 100 contracts) | Calculated across the same tracked markets; fees vary by contract price, market, and order type, with takers generally paying more than market-makers |
| Wallet/cannibalization claims | Described as based on "actual customer wallets" — i.e., real customer-level betting data rather than market-level pricing, though the report doesn't specify the exact dataset or sample |
