Mint, Transfer, Merge
Three settlement paths: mint new pairs, transfer existing shares, or merge a complete set back into USDC.
Under the hood, each market is backed by USDC held in a vault, with Yes and No shares minted against it 1:1. There are three things that can happen when two orders match.
Mint — both sides want to buy
If one trader wants to buy Yes at 47¢ and another wants to buy No at 53¢, they together put 47¢ + 53¢ = $1 into the vault. The vault mints one Yes share and one No share — one to each. No existing shares change hands; the supply of both sides increases by one.
Transfer — one buyer, one seller
If you want to buy Yes at 47¢ and someone already holding Yes wants to sell at 47¢, the share just changes hands. They get your 47¢, you get their Yes share. No new shares minted, vault USDC unchanged.
Merge — both sides want to sell
If two traders both want to sell — one selling Yes, one selling No — the system burns the matched complete set and returns $1 from the vault, split per their prices. The market's outstanding supply on both sides goes down.
You usually don't need to think about which path you're on; the matcher picks the cheapest one for both sides. But all three exist because they all preserve the invariant: every share in circulation is backed by exactly $1 in the vault.