# Instant Trading

Instant trading is where solvers really shape the user experience. From a trader’s perspective, it feels like a CEX: they click “Buy” or “Sell” and the trade just goes through, without a wallet popup for every action. Under the hood, that’s only possible because the trader has delegated certain permissions to you, the solver, and you’ve wired your systems to act immediately when they send an instruction.

The flow starts with the trader creating a sub-account through the Multi-Account contract and then delegating a small set of functions to your Party B address. They approve things like `sendQuote`, `requestToClosePosition`, `requestToCancelQuote`, and `requestToCancelCloseRequest` for that sub-account. This doesn’t give you custody of their funds; it just lets you submit the same trading calls they could make themselves, without needing their wallet to sign every time. On top of that, they go through a login flow (often SIWE-based), where they sign a message off-chain to prove they control the account. Your backend verifies that signature and returns an access token that frontends can attach to every API call.

Once that is in place, instant trading becomes possible through simple [API calls](https://docs.symm.io/solver-documentation/building-a-solver-on-symmio/instant-trading/instant-trading-solvers). When the user hits “Open Long 10x” in the UI, the frontend sends a request to your hedger API with their sub-account, market, size, and any extra parameters. Your system does all the same [work as it would when opening a regular position](https://docs.symm.io/solver-documentation/building-a-solver-on-symmio/instant-trading/instant-trading-condition-checks) and then calls the SYMMIO contracts directly using the delegated functions. There is no pause to wait for a wallet signature because you are the one submitting the transaction. When the user hits “Close,” the same thing happens: the frontend calls you, you verify, and you submit the close on-chain on their behalf.
