The Heartland Line
Prediction markets vs sportsbooks for Big Ten football: where the price comes from
A sportsbook sets the line and builds its margin into both sides. A prediction market matches fans against each other and charges a fee, or none. What that means for a $100 position on a Big Ten game.
On any Big Ten Saturday there are two very different kinds of venue putting a price on the same game. They arrive at that price from opposite directions, and the difference shows up in what a winning position pays.
The sportsbook model
A sportsbook is the counterparty. It writes the line, takes the other side of every ticket and protects itself by shading both prices. A game it considers a genuine toss-up does not go up at +100 on each side; it goes up at -110 on each side. Convert those two prices to probabilities and they add to about 104.8%. The extra is the book's margin, usually called the vig or the hold, and it is in place before anyone has touched the ball.
Nobody hands you an invoice for it. It lives inside the odds, which is why two books showing what looks like the same line can pay different amounts on the same $100.
The prediction-market model
A prediction market is not a counterparty. It is a matching engine. A fan who thinks Indiana wins is paired with a fan who thinks Indiana loses, and the price is wherever their orders meet, quoted in cents as a probability. A contract on Indiana at 65 cents pays $1 if Indiana wins. With no house position to protect, nobody has a reason to shade the line.
The venues make their money in different ways:
- Novig takes no vig and charges no trading fee on the position. What you see on the screen is what you get.
- Kalshi charges a taker fee scaled by price, built on a 7% rate. It is largest on a coin flip and shrinks as one side becomes a heavy favorite.
- Polymarket also charges a fee on many sports markets, with a rate that varies by market.
The same game, three returns
Suppose a Big Ten home favorite trades at 60 cents, the equivalent of -150.
| Venue | Quote | Profit on a winning $100 |
|---|---|---|
| Prediction market, no fee | 60¢ (-150) | $66.67 |
| Sportsbook | -160 | $62.50 |
| Prediction market, 7% fee rate | 60¢ | about $62.13 |
At the same 60-cent price, the fee alone costs about $4.50 per $100. The sportsbook gets to a similar place by moving the price instead of adding a charge. Only the no-fee venue pays the full value of the probability on the screen. The board runs this calculation for every Big Ten game and sorts each side from best return to worst, so you never have to do the arithmetic yourself. How the board is read walks through the formula.
Why this matters across the Big Ten map
The conference now runs from New Jersey to California, and the betting rules change at every state line. Several Big Ten states have no statewide online sportsbook at all: California, Minnesota, Washington and Wisconsin among them. For fans living in those four states, the sportsbook rows on the board are mostly prices they cannot take.
Prediction markets are overseen federally by the CFTC rather than licensed state by state, which is why they reach places the books do not. Novig is a CFTC-designated exchange available in 47 states. The three where it is not available are Arizona, Michigan and Nevada, so Michigan is the one Big Ten state where Novig is off the table. The state pages set out what is open where you live, and our state-by-state rundown covers where the law stands this fall.
What "no vig" does not promise
No vig is not the same as a guaranteed better price. On a prediction market the price comes from other traders and moves with them, and a thinly traded game can show a wider gap between the best buy and best sell than a sportsbook's built-in margin. When that happens it shows up on the board, because the hold column measures every venue's two sides the same way. Most Big Ten games carry enough volume that the gap is close to zero. The board does not take that on faith; it measures it each time it refreshes.
