RizonHorizon contract vs event contract: what's the difference?
An event contract fixes the question and lets the price float from 0¢ to 100¢. A horizon contract fixes the price at 50/50 and lets the strike float.
Short answer: Both are binary contracts on a future outcome, and they differ in what's fixed. An event contract fixes the question ("Will Republicans win 195–199 House seats?") and lets the price float between 0¢ and 100¢. A horizon contract fixes the price (it pays 2×, the same as 50¢ for $1) and lets the strike float ("Higher or Lower than 193.5 seats?"). So one number takes a dozen event contracts, each with its own book, or one horizon book. Event contracts fit yes-or-no questions and can be sold before expiry. Horizon contracts fit numbers and run to expiry.
The US Commodity Futures Trading Commission describes event contracts as "often based on yes-no scenarios", with "a fixed payout (usually $1) and an expiration". Polymarket and Kalshi list them. A horizon contract has the same all-or-nothing payoff and turns the quote inside out.
The difference in one table
| Event contract | Horizon contract | |
|---|---|---|
| What you buy | Yes or No on one question | Higher or Lower on a number |
| What's fixed | The question, and any strike in it | The price: you pay your size and a win pays 2× |
| What the book quotes | A price from 0¢ to 100¢ | The strike, in the number's own units |
| A price means | The chance the market gives that question | Nothing: every contract is 50/50 |
| A forecast of the number | Add up the buckets | The book's midpoint |
| One number takes | Many books: 10 for House seats on Polymarket, about 30 for Elon Musk's weekly posts | One book |
| Risk and reward | Pay 90¢ to make 10¢, or 5¢ to make 95¢ | Risk your size to win your size |
| Taker fee at 50¢ | About 1.75¢ a share on Polymarket and Kalshi | None on Rizon |
| Before expiry | Sell it at the bid | Hedge it with the other side |
| Fits | Any yes-or-no question | Anything with a number: a price, a count, a rate, a date |
| Real money | Yes, on regulated and crypto venues | Not yet: Rizon is paper |
The same question, quoted both ways
Republican House seats after the 2026 midterms, on Polymarket on Oct 29, 2026:
| Republican seats | Bid (¢) | Ask (¢) | Mid (¢) |
|---|---|---|---|
| Under 190 | 33 | 34 | 33.5 |
| 190–194 | 12 | 14 | 13 |
| 195–199 | 13 | 15 | 14 |
| 200–204 | 12.6 | 14.4 | 13.5 |
| 205–209 | 12.9 | 15.1 | 14 |
| 210–214 | 3.4 | 4.0 | 3.7 |
| 215–219 | 4.6 | 7.3 | 5.95 |
| 220–224 | 2.7 | 3.8 | 3.25 |
| 225–229 | 0.8 | 1.6 | 1.2 |
| 230 or more | 0.2 | 0.3 | 0.25 |
And the one line that replaces them, Rizon's HOUSE-R-2026 on Nov 2, 2026:
| Best bid (seats) | Best ask (seats) | Midpoint (seats) |
|---|---|---|
| 191.5 | 194.5 | 193 |
The bucket table holds more information: it's the whole distribution, and a trader can take a view on its shape. The strike book holds the part most traders want: where the middle is, in the number's own units, and how much it costs to disagree.
What it costs to take a view
Say you think Republicans will win 200 seats or more. On Polymarket on Oct 29 that meant buying seven buckets, each at its own ask:
| Bucket | Ask (¢) | Mid (¢) |
|---|---|---|
| 200–204 | 14.4 | 13.5 |
| 205–209 | 15.1 | 14 |
| 210–214 | 4.0 | 3.7 |
| 215–219 | 7.3 | 5.95 |
| 220–224 | 3.8 | 3.25 |
| 225–229 | 1.6 | 1.2 |
| 230 or more | 0.3 | 0.25 |
| Total for $1 if 200 or more | 46.5 | 41.85 |
Seven orders across seven books, with 4.65¢ of spread paid on a position worth about 42¢. On a horizon book it's one order. The same distribution puts the best ask near 197.5, and buying there holds Higher at 197.5: it wins on 198 seats or more and returns 2×. It isn't the same trade, since it wins over a wider range and costs half its payout rather than 46.5¢ on the dollar. But it's one view on the number, one order and one spread.
Where event contracts are the better fit
- A question with no number. "Will the bill pass?" has no count, level or date to quote, unless you turn it into "when?", and then it's a date market.
- Lumpy outcomes. When one result holds most of the probability, no strike splits it 50/50. The Fed's December 2026 decision traded 76.5¢ for a hike and 21.5¢ for a hold. A price in cents handles that directly.
- Long shots and near-certainties. If you want to pay 5¢ to make 95¢, or 95¢ to make 5¢, only a floating price offers it. Every horizon contract is the 50¢ case.
- Getting out early. You can sell an event contract at the bid. A horizon contract runs to expiry, and you can only hedge it.
- Liquidity and real money, today. Polymarket and Kalshi have real volume behind their prices. Rizon's books are paper, quoted by bots that read those same venues.
Where horizon contracts are the better fit
- A forecast edge is worth the most at 50/50. The value of a better forecast scales with the density at the strike, which peaks at the median. Of 173 prices we recorded on Oct 29, 2026 on Polymarket and Kalshi markets on Rizon's questions, 98 were under 10¢ or over 90¢ and 5 were between 40¢ and 60¢. The arithmetic is here.
- One book. A dozen buckets split one number's liquidity across a dozen books. One strike book puts it all in one place.
- The forecast is on the screen. The midpoint says "193 seats". With buckets you normalise the prices and interpolate, as in how to price a horizon contract.
- Simple accounting. Every position risks its size to win its size, so a win rate and a PnL are the same thing to read across every market.
- Nobody arrives late. On a rolling market, each contract gets its full horizon from your own fill rather than what's left of a window. The data on late arrivals.
FAQ
Is a horizon contract an event contract?
Loosely, yes: both are binary contracts on an outcome, with a fixed payout and an expiry. In practice "event contract" means Yes or No at a floating price, and a horizon contract is Higher or Lower at a fixed price, with the strike floating instead.
Can an event contract be converted into a horizon contract?
Not one contract, but a set can. A ladder of event contracts on the same number gives you its distribution, and the distribution's median is the fair strike of a horizon contract. Open-source bots quote Rizon's books exactly that way, from Polymarket's and Kalshi's prices.
Which pays more, an event contract or a horizon contract?
Neither pays more by design: both are fair at the right price. An event contract's payoff depends on its price (a 25¢ contract returns 4×), while a horizon contract always returns 2×. What differs is where a forecast edge is worth the most, and that's at the 50¢ end.
Do horizon contracts trade on Polymarket or Kalshi?
No. Polymarket and Kalshi list event contracts. As of November 2026, Rizon is the only exchange we know of that lists horizon contracts, with paper money.
Why not just list event contracts near 50¢?
You can't hold them there. A market priced at 50¢ today drifts toward 0¢ or 100¢ as news arrives, and a new question has to be listed to get back to the middle. A horizon book moves the strike instead, so the middle is always where it trades.