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A limit order executes only at your price or better — never worse. A buy limit fills at your limit price or lower; a sell limit fills at your limit price or higher. You trade certainty of execution for control over price: you’re guaranteed the price, but not that the order fills at all. This page walks the full lifecycle end-to-end — place the order over REST, then follow it to a fill over the WebSocket — so you can use it as the template for every other order type.
New to the module? Start with Order Flow. The subscribe handshake shown here is the same for all order types.

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When to use it

  • You have a target entry or exit price and are willing to wait.
  • The spread is wide or the name is volatile, and a market order could fill at a bad price.
  • You want to rest an order on the book (often with GTC) and let the market come to you.

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How it works

  1. You POST /v1/orders with type: "LIMIT" and a price.
  2. The order rests on the book as NEW until the market reaches your price.
  3. When it trades through your price it fills — fully (FILLED) or in pieces (PARTIALLY_FILLED).
  4. If it never reaches your price, a DAY order ends the session EXPIRED; a GTC order keeps resting until filled or cancelled.

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Request

FieldTypeRequiredDescription
typestringyesMust be "LIMIT".
pricestringyesYour limit price as a decimal string. The order fills at this price or better.
sidestringyesBUY, SELL, SELL_SHORT, or BUY_TO_COVER.
qtystringyesNumber of shares as a decimal string.
timeInForcestringyesDAY, GTC, IOC, or FOK. Use DAY to expire at the close, GTC to rest until cancelled.
stopPricestring—Do not send for a plain limit order. (That would make it a stop-limit.)

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Step 1 — Place the order

cURL
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": "LIMIT",
    "qty": "100",
    "price": "150.50",
    "timeInForce": "DAY"
  }'
Request body
{
  "tradingAccountId": "ACC123456",
  "symbol": "AAPL",
  "side": "BUY",
  "type": "LIMIT",
  "qty": "100",
  "price": "150.50",
  "timeInForce": "DAY"
}
price is required for limit orders. Omitting it is rejected. Send it as a string ("150.50"), not a number.

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Response

{
  "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"
}
The order is now working on the book. It has not filled yet — cumQty is 0 and leavesQty is the full quantity. Fills arrive over the WebSocket.

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Listen for updates

This is the WebSocket half of the round-trip. The handshake below is identical for every order type — only the account.order payload differs.

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Step 2 — Connect & authenticate

Open the connection and authenticate within 5 seconds: 
const ws = new WebSocket("wss://api.aries.com/v1/accounts/ws");

ws.onopen = () => {
  ws.send(JSON.stringify({
    type: "request",
    id: "auth-001",
    payload: {
      method: "post",
      path: "/auth",
      body: { token: "YOUR_ACCESS_TOKEN" }
    }
  }));
};
The server replies with an authSuccess event: 
{
  "type": "event",
  "payload": {
    "action": "authSuccess",
    "data": { "expiresIn": 3900000 },
    "id": "auth-001",
    "timestamp": 1703001234567
  }
}

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Step 3 — Subscribe to the account topic

Subscribe request
{
  "type": "subscribe",
  "id": "req-002",
  "payload": {
    "topic": "account",
    "params": { "accountId": "ACC123456" }
  }
}
You immediately receive a snapshot of current orders, positions, and balance, then a live stream of events. (Subscribe before placing so you never miss an update.)

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Step 4 — Receive order events

As the limit order works and fills, you get account.order events. Watch ordStatus, cumQty, and leavesQty: 
{
  "type": "event",
  "timestamp": "2024-01-15T10:30:00Z",
  "payload": {
    "topic": "account",
    "name": "account.order",
    "target": "account:ACC123456",
    "data": {
      "ordId": "ORD-12345",
      "clOrdId": "CLIENT-001",
      "accountId": "ACC123456",
      "symbol": "AAPL",
      "side": "BUY",
      "type": "LIMIT",
      "timeInForce": "DAY",
      "qty": "100",
      "price": "150.50",
      "ordStatus": "NEW",
      "cumQty": "0",
      "leavesQty": "100",
      "avgPrice": "0",
      "securityType": "EQUITY",
      "category": "EQUITY",
      "createdAt": "2024-01-15T10:30:00Z",
      "updatedAt": "2024-01-15T10:30:00Z"
    }
  }
}
Match events to your order by clOrdId. Drive your UI off ordStatus and the cumQty/leavesQty pair: cumQty is what’s filled, leavesQty is what’s still working. After the first snapshot, later updates may include only the fields that changed.
For the full WebSocket reference — every topic, reconnection strategy, session expiry, and the complete field/enum tables — see Account Updates WebSocket.

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Modify or cancel a resting limit order

Because a limit order can rest for a while, you’ll often want to re-price or cancel it.
Replace — move the limit to 150.25
{
  "origClOrdId": "CLIENT-001",
  "tradingAccountId": "ACC123456",
  "symbol": "AAPL",
  "side": "BUY",
  "type": "LIMIT",
  "qty": "100",
  "price": "150.25",
  "timeInForce": "DAY"
}
A successful replace returns a new clOrdId. To replace again, send that new ID as origClOrdId — the old one is invalidated. See Replace Order.
Cancel
{
  "origClOrdId": "CLIENT-001",
  "tradingAccountId": "ACC123456",
  "symbol": "AAPL",
  "side": "BUY"
}

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Next steps

Stop order

Trigger a market order when a price level is breached.

Stop-limit order

Combine a trigger with a price cap.

Single-leg option

Apply a limit price to a single call or put.

Account Updates WebSocket

The full streaming reference for order, position, and balance events.