> ## Documentation Index
> Fetch the complete documentation index at: https://finance.dev/llms.txt
> Use this file to discover all available pages before exploring further.
# Market Order
> Buy or sell an equity immediately at the best available price. The simplest order type — no price fields, just symbol, side, and quantity.
A **market order** executes immediately at the best price currently available. You are trading **speed and certainty of execution** for **price uncertainty** — you'll get filled, but you don't control the exact price. Use it when getting in or out *now* matters more than the precise fill price.
New to the Orders module? Read [Order Flow](/api-reference/orders/order-flow) first for the big picture — one endpoint, how the type is inferred, and how to listen for updates. This page assumes you've connected and authenticated.
***
## When to use it
* You want to be filled right away and accept the prevailing price.
* The instrument is liquid (tight spread), so the market price is close to what you see.
Avoid market orders on illiquid or fast-moving names — a wide spread or a gap can fill you far from the last-traded price. In those cases use a [Limit order](/api-reference/orders/limit-order).
***
## How it works
1. You `POST /v1/orders` with `type: "MARKET"` and **no price fields**.
2. The order is accepted (`PENDING_NEW` → `NEW`) and routed immediately.
3. It fills — often instantly and in full, sometimes in pieces (`PARTIALLY_FILLED` → `FILLED`).
4. Each step arrives as an `account.order` event on the [Account WebSocket](/websockets/account-updates).
A `DAY` market order placed during regular hours essentially always fills the same session.
***
## Request
| Field | Type | Required | Description |
| ----------- | ------ | -------- | --------------------------------------------------- |
| `type` | string | yes | Must be `"MARKET"`. |
| `side` | string | yes | `BUY`, `SELL`, `SELL_SHORT`, or `BUY_TO_COVER`. |
| `qty` | string | yes | Number of shares as a decimal string. |
| `price` | string | — | **Do not send.** Market orders have no limit price. |
| `stopPrice` | string | — | **Do not send.** Market orders have no trigger. |
### Example — buy 100 shares of AAPL at market
```bash cURL theme={null}
curl -X POST https://api.aries.com/v1/orders \
-H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
-H "Content-Type: application/json" \
-d '{
"tradingAccountId": "ACC123456",
"symbol": "AAPL",
"side": "BUY",
"type": "MARKET",
"qty": "100",
"timeInForce": "DAY"
}'
```
```json Request body theme={null}
{
"tradingAccountId": "ACC123456",
"symbol": "AAPL",
"side": "BUY",
"type": "MARKET",
"qty": "100",
"timeInForce": "DAY"
}
```
That's the entire body. No `price`, no `stopPrice`. The absence of a `legs` array makes this an **equity** order.
### Example — sell to close 50 shares
```json theme={null}
{
"tradingAccountId": "ACC123456",
"symbol": "TSLA",
"side": "SELL",
"type": "MARKET",
"qty": "50",
"timeInForce": "DAY"
}
```
***
## Response
```json theme={null}
{
"success": true,
"clOrdId": "CLIENT-001",
"status": "NEW",
"symbol": "AAPL",
"side": "BUY",
"qty": "100",
"cumQty": "0",
"leavesQty": "100",
"avgPrice": "0",
"transactTime": "2024-01-15T10:30:00Z"
}
```
Keep the `clOrdId` — it identifies this order in every WebSocket update and is what you pass as `origClOrdId` to cancel it.
***
## Watch it fill
A market order typically fills moments after acknowledgement. You'll see the fill as an `account.order` event with `ordStatus: "FILLED"` and a real `avgPrice`:
```json account.order event theme={null}
{
"type": "event",
"timestamp": "2024-01-15T10:30:01Z",
"payload": {
"topic": "account",
"name": "account.order",
"target": "account:ACC123456",
"data": {
"ordId": "ORD-12345",
"clOrdId": "CLIENT-001",
"accountId": "ACC123456",
"symbol": "AAPL",
"side": "BUY",
"type": "MARKET",
"timeInForce": "DAY",
"qty": "100",
"ordStatus": "FILLED",
"cumQty": "100",
"leavesQty": "0",
"avgPrice": "150.45",
"securityType": "EQUITY",
"category": "EQUITY",
"createdAt": "2024-01-15T10:30:00Z",
"updatedAt": "2024-01-15T10:30:01Z"
}
}
}
```
For the subscribe handshake and the full event schema, see [Limit order → Listen for updates](/api-reference/orders/limit-order#listen-for-updates) or the complete [Account Updates WebSocket](/websockets/account-updates) reference.
***
## Common rejections
| `ordRejReason` / reason | Cause |
| ----------------------- | ------------------------------------------------------------------------------------------------ |
| `ORDER_EXCEEDS_LIMIT` | Not enough buying power for the notional. |
| `UNKNOWN_SYMBOL` | The `symbol` isn't recognized. |
| `EXCHANGE_CLOSED` | A `DAY` market order sent while the market is closed. Use a limit order or wait for the session. |
| `TOO_LATE_TO_ENTER` | Order arrived after the cutoff for the session. |
***
## Next steps
Control your fill price instead of taking the market.
Trigger a market order only once a price level is hit.
Interactive reference and full schema for `POST /v1/orders`.
Estimate cost and buying-power impact before placing.