> For the complete documentation index, see [llms.txt](https://docs.symm.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.symm.io/trader-documentation/building-a-trading-bot/part-2-trading/closing-a-position.md).

# Closing a position

Closing is one EIP-712 op. The trick is `signerAccount.addr`: for closes it's the **virtual account**, not the sub-account.

Why? Because as far as the Symmio core is concerned, it's that virtual address that holds the quote. The core looks up `quotes[quoteId].partyA` and checks that the caller (after the AccountLayer's signer-context forwarding) matches. That `partyA` is the VA. Sign as the sub-account and the core rejects the call with an authorization error that doesn't exactly say "wrong account"; it just fails.

### Compute close price

Slippage runs in the *opposite direction* to opens: when you close a long, you're selling, so you accept a *lower* price; when you close a short, you're buying back, so you accept a *higher* price.

| Side closing | Worst-acceptable close price          |
| ------------ | ------------------------------------- |
| CLOSE LONG   | `price = mark × (1 − slippage / 100)` |
| CLOSE SHORT  | `price = mark × (1 + slippage / 100)` |

Quantize to `price_precision` and convert to wei.

### Sign one `SignedOperation`

The envelope is the same `SignedOperation` struct as for opens, the domain is the same `SymmioInstantLayer`, and the signer is the same session key. The fields that differ:

* `target`: Symmio Core (same as `sendQuote`)
* `signerAccount.addr`: **virtual account**
* `callData`: selector `0x501e891f` followed by ABI-encoded `(quoteId: uint256, closePrice: uint256, quantityToClose: uint256, orderType: uint8, deadline: uint256)`. `orderType = 1` for MARKET.

### POST as a JSON array

```
POST <instant-close endpoint>
Content-Type: application/json

[
  {
    "signedOperation": { ... },
    "signature": "0x..."
  }
]
```

Note the array. **Open is a JSON object, close is a JSON array**. Mixing them up may cause failures on the server side.

The solver responds with `200 null` when the close is queued. The notifications WS will show `FillCloseRequest` once it fills on-chain.


---

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