Core Concepts
Before trading, spend three minutes on four concepts — they run through the entire protocol.
Market
Every market is created around one binary question, e.g.:
"Will BTC break $200,000 before the end of 2026?"
A market has an explicit expiry (Trading Closes) and an oracle data source (Oracle Feed). Trading is free until expiry; after expiry the oracle delivers a Yes / No result.
Outcome Shares (YES / NO tokens)
Each market mints two SPL tokens:
- Holding 1 YES: redeemable for 1 USDC if the result is Yes; worthless otherwise.
- Holding 1 NO: redeemable for 1 USDC if the result is No; worthless otherwise.
Both tokens have 2 decimals and can be held and transferred like any SPL token.
Complete Set
1 USDC ⇌ 1 YES + 1 NO
Anyone can mint a YES + NO pair for 1 USDC at any time, and redeem a pair back into 1 USDC at any time. This anchors the whole price system:
- Whatever the outcome, one YES + one NO is worth exactly 1 USDC;
- Therefore prices always satisfy
P(Yes) + P(No) = 1— any deviation creates a risk-free arbitrage that pulls prices back.
Price = Probability
The YES price is the market's collective probability estimate:
| YES price | Meaning |
|---|---|
| 0.65 USDC | The market believes the event has a 65% chance of happening |
| 0.10 USDC | Very unlikely (10%) |
| 0.95 USDC | Nearly certain (95%) |
The NO price is always 1 − P(Yes). Prices range from 0.001 to 1.000 USDC.
Buy YES at 0.65 and, if you are right, each share earns 1 − 0.65 = 0.35 USDC (a 53.8% return); if you are wrong it goes to zero.
Order Book, Not AMM
Unlike many on-chain prediction markets, Astromarkets matches trades on a central limit order book (CLOB) rather than an AMM:
- Market order: fills immediately at the best resting price; the taker pays a 0.2% fee;
- Limit order: rests on the book at your chosen price; makers who don't take pay no taker fee.
More distinctively, there is cross matching: your resting "Buy NO @ 0.30" can fill directly against someone's "Buy YES @ 0.70+" — the protocol mints a complete set and delivers one side to each. The two directions of liquidity merge into a single depth pool; see Matching Engine.
Market Lifecycle (overview)
① Create ──► ② Trading ──► ③ Expiry, oracle resolves ──► ④ Dispute window (optional) ──► ⑤ Settlement ──► ⑥ Close
- Create: creator stakes a ≥600 USDC deposit and configures the oracle feed.
- Trading: buy/sell YES / NO freely, mint / redeem complete sets.
- Result submission: after expiry anyone can trigger the oracle read and write the preliminary result.
- Dispute window: within 24 hours anyone who believes the result is wrong can stake a challenge → 48h voting → optional DAO review.
- Settlement: winning tokens redeem the vault's USDC pro rata; losing tokens go to zero.
- Close: once all assets are drained, the creator closes the market and reclaims rent.
Detailed steps are in the User Guide; the underlying state machine is in Market State Machine.