Glossary: horizon, strike, push, 2× payout and other up/down trading terms

Short answer: An up/down contract pays if the underlying finishes above (up) or below (down) a strike at expiry. In a fixed window, the strike is the window's price to beat and everyone shares one close; in a horizon contract, each trade starts at its own fill and runs a set time. A push is a finish exactly at the strike, refunded to both sides. A 2× payout means you pay your size and get twice it back if you're right. The resolution source is the feed that decides it, and makers rest orders while takers trade against them.

Each term has its own anchor, so you can link straight to it, for example /learn/up-down-trading-glossary#push.

Terms#

Horizon#

How long a contract runs, measured from the moment it's traded. On Rizon, Bitcoin contracts have horizons of 15 seconds, 1 minute and 5 minutes, and Elon Musk post-count contracts (launching soon) 15 minutes, 1 hour and 6 hours. A market is an underlying plus a horizon: BTC-15s, BTC-1m, BTC-5m. See fixed windows vs horizon contracts.

Per-fill expiry#

Each contract expires a fixed time after its own fill, not at a shared close. On Rizon the expiry is a whole second about one horizon after the fill; every fill in the same second shares that expiry, so there's one contract per horizon per second. Read the expiry from the trade (expiresAt in the API) rather than computing it.

Strike#

The level the underlying has to finish beyond. Up wins above it, down below it. In a cents market the strike is fixed and the price moves; in a strike book, such as Rizon's, the price is fixed and the strike is what's quoted, the way a futures book quotes a price. Rizon's Bitcoin strikes are whole dollars. See strike vs probability.

Push#

A contract that finishes exactly at its strike: neither side wins, and both get their size back. On Rizon's Bitcoin markets a push also happens if there's no price in the 5 seconds before expiry. Rizon's Elon Musk markets put strikes on half-posts (14,040.5), and a count never lands on one, so they can't push. Fixed-window venues settle ties by rule instead: Up wins on Polymarket and Kalshi.

2× payout#

You pay your size; if you're right you get twice it back, and if you're wrong you get nothing. A $10 position returns $20 or $0. That's the same as buying a $1 contract at exactly 50¢, which is why a 2× book competes on the strike rather than on the price. With no fees, the break-even win rate is 50%, pushes aside.

Fixed window#

A block of clock time, such as 3:15 to 3:20, that every trader in that market shares: one start, one price to beat, one close. Polymarket lists Bitcoin windows of 5 minutes, 15 minutes and 4 hours; Kalshi lists 15-minute ones. Arriving late means less time and a price that has already moved: see what a late arrival finds.

Price to beat#

A fixed window's opening price: the strike every Up and Down in that window is measured against. On Polymarket it's the Chainlink 60-second TWAP at the window's start; on Kalshi, a 60-second average of CF Benchmarks' index before the open, shown as the "Target Price". Each window's price to beat is the previous window's final value.

Resolution source#

The data feed that decides the outcome, named in the market's rules. Polymarket's 5-minute Bitcoin markets resolve on Chainlink's BTC/USD 60-second TWAP stream; Kalshi's 15-minute markets on CF Benchmarks' Bitcoin Real Time Index (BRTI); Rizon's Bitcoin markets on the last Coinbase price at or before expiry (Kraken as a backup). Different feeds differ by a few dollars at any second, which decides close finishes.

TWAP#

A time-weighted average price: the average of the price over a window of time, such as the last 60 seconds. Settling on a TWAP instead of a single price makes the final seconds count less. Polymarket moved its crypto up/down markets to Chainlink TWAPs in August 2026 (changelog). See what averaging does to late reversals.

Implied probability#

A price in a cents market read as a chance. A share that pays $1 if right and costs 62¢ implies about a 62% chance, before fees. On a 2× strike book, the same idea applies to strikes: the implied probability of up at a strike is how often the price finishes above it.

Up and down#

The two sides. Up wins if the underlying finishes above the strike, down if below. On Rizon's book, up is buying (bids) and down is selling (asks); a buyer of up prefers a lower strike, a seller (down) a higher one. An up and a down at the same strike and expiry cancel out.

Bid and ask#

The best price someone will buy at (bid) and sell at (ask). On Rizon they're strikes: the best bid is the highest strike an up buyer will take, the best ask the lowest strike a down seller will take. A market up order fills at the best ask, a market down order at the best bid.

Spread#

The gap between the best bid and the best ask: in cents on a cents market, in dollars of strike on a strike book. It's what a taker pays for trading now. Rizon's market maker usually quotes Bitcoin 2 strikes wide at 15 seconds, 4 at 1 minute and 9 at 5 minutes, wider while volatility runs high.

Maker and taker#

A maker's order rests in the book; a taker's order arrives and trades against it. Many venues charge them differently: on Polymarket's crypto markets takers pay a fee and makers pay none (fees). Rizon charges neither.

Market maker#

A trader who quotes both sides continuously so others can always trade. Rizon's is an ordinary account trading through the public API with the same limits as anyone, ranked on the leaderboard like everyone else.

Sigma#

The typical size of a move over a horizon: one standard deviation. Rizon's API reports each market's realised sigma, in dollars for Bitcoin, from recent ticks. In the 30 days to 26 October 2026, Bitcoin's median absolute move was $5.07 over 15 seconds, $15.37 over 1 minute and $36.55 over 5 minutes (the data).

Settlement#

Paying out at expiry. On Rizon, a Bitcoin contract settles on the last price at or before its expiry second; an Elon Musk contract on XTracker's count at its expiry, once the counter has been read after it. Positions can't be closed early: you hedge with a later one.

Paper trading#

Trading with practice money in a real market: live prices, a real order book, other traders on the other side. Rizon is a paper exchange: every account starts with $1,000 and can refill once below $10. See how to practise for free.

FAQ#

What is a horizon contract?#

A contract that starts when you trade and runs for a set time (on Rizon, 15 seconds, 1 minute or 5 minutes on Bitcoin), against a strike set at your fill. Unlike a fixed window, it doesn't share a start or an end with anyone else's.

What does a push mean?#

The underlying finished exactly at the strike, so neither side wins and both get their money back.

What is a price to beat?#

The opening price of a fixed window, which every Up and Down in that window is measured against at the close.

What is the difference between a maker and a taker?#

A maker's order rests in the book until someone trades with it; a taker's order trades immediately against resting orders. On many venues takers pay fees and makers don't.

What does a 2× payout mean?#

You pay your size and get twice it back if you're right, nothing if you're wrong: the same as buying a $1 contract at 50¢.