Understanding Order Types

The Core Instructions: Market and Limit Orders

At the most basic level, every trade instruction comes down to a decision between speed and price. This is handled by market and limit orders.

To get a conceptual overview, let's start with a short video that explains the four main order types.

Now, let's break those down from an engineering perspective, keeping your Angel One API in mind.

1. Market Order

A market order is the most straightforward instruction: "Buy or sell these shares now at the best available price."

• Mechanism: Your order is matched with the best available counter-party order in the market's order book. If you are buying, you'll pay the lowest available seller's price (the "ask"). If you're selling, you'll get the highest available buyer's price (the "bid").

• Advantage: Guaranteed execution (as long as there is liquidity). It's the fastest way to enter or exit a position.

• Disadvantage: No price guarantee. The price you get might be different from the last traded price you saw, a phenomenon known as slippage. This is especially risky in volatile or thinly traded stocks.

• API Implementation (Angel One): You specify this by setting the ordertype parameter to 'MARKET'. No price parameter is needed.

  {
      "ordertype": "MARKET",
      "quantity": 10,
      ...
  }
  

2. Limit Order

A limit order adds a condition to the instruction: "Buy these shares only if the price is at or below X," or "Sell these shares only if the price is at or above Y."

• Mechanism: Your order is placed in the order book and will only execute if the market price reaches your specified limit price.

• Advantage: Complete price control. You will never pay more than your limit for a buy or receive less than your limit for a sell. This protects you from slippage.

• Disadvantage: No execution guarantee. The market price may never reach your limit, and your order may go unfilled or only be partially filled.

• API Implementation (Angel One): You set ordertype to 'LIMIT' and must provide the price parameter with your desired limit price.

  {
      "ordertype": "LIMIT",
      "price": "150.50",
      "quantity": 10,
      ...
  }
  

Conditional Orders for Risk and Entry Management

Beyond simple execution, you need orders that can react to market conditions. This is where stop-loss orders come in. They are foundational for any automated risk management system.

For a deeper dive, let's consult a resource from your chosen broker, Angel One.

3. Stop-Loss (SL) Order

A stop-loss order is an inactive order that is "activated" or sent to the exchange only when a specific price, the trigger price, is reached.

Its name comes from its most common use: to limit losses on an existing position. However, it can also be used to initiate a new position.

There are two main variants, which map directly to the API parameters you'll use:

• Stop-Loss Market (SL-M) Order:

  • Mechanism: When the stock's price hits your triggerprice, a MARKET order is sent to the exchange.
  • Use Case: To exit a losing position quickly. For example, you buy a stock at ₹100 and set an SL-M order with a trigger at ₹95. If the price drops to ₹95, a market sell order is immediately placed.
  • Advantage: High probability of execution once triggered.
  • Disadvantage: Subject to slippage. In a fast-falling market, your execution price could be well below ₹95.
  • API Implementation (Angel One): Set ordertype to 'STOPLOSS_MARKET' and provide the triggerprice.

• Stop-Loss Limit (SL-L) Order:

  • Mechanism: When the stock's price hits your triggerprice, a LIMIT order is sent to the exchange with a pre-defined price.
  • Use Case: To control the price of your exit after a stop is triggered. For example, you set a trigger at ₹95 and a limit price of ₹94.80. If the price drops to ₹95, a limit sell order is placed at ₹94.80. The broker will try to sell, but not for less than ₹94.80.
  • Advantage: Protects you from excessive slippage on the exit.
  • Disadvantage: Your order may not get filled if the market gaps down violently past your limit price. You wanted to get out at ₹95, the market gapped to ₹94.50, and your limit sell order at ₹94.80 is left unfilled as the price continues to fall.
  • API Implementation (Angel One): Set ordertype to 'STOPLOSS_LIMIT' and provide both a triggerprice and a price (your limit).

This image from the Angel One platform shows how these orders appear in their system. Note the "SL MARKET" order type for INFY.

The All-in-One Tool: Bracket Orders (Robo Orders)

For a fully automated strategy, managing entry, profit-taking, and stop-loss orders separately can be complex. A bracket order is a powerful compound order type designed to handle all three in a single instruction. Angel One refers to this as a Robo Order.

A Robo/Bracket order consists of three legs:

1. The initial entry order (e.g., buy 100 shares of XYZ at a limit of ₹1000).
2. A profit-taking order (e.g., sell those 100 shares if the price reaches ₹1050).
3. A stop-loss order (e.g., sell those 100 shares if the price drops to ₹990).

The key feature is that the profit-taking and stop-loss orders are linked in a One-Cancels-the-Other (OCO) relationship. If the target price is hit and the position is sold for a profit, the stop-loss order is automatically canceled. Conversely, if the stop-loss is triggered, the profit-taking order is canceled.

Let's see how Angel One describes their implementation.

• Advantage: This is ideal for automation. It encapsulates an entire trade plan in a single API call, reducing the complexity of state management in your bot. The server at the broker's end manages the OCO logic.

• Disadvantage: It is typically restricted to intraday (MIS) trades and may not be available for all securities.

• API Implementation (Angel One): This is specified using a special variety parameter. You set variety to 'ROBO'. You then provide the price for the initial entry, the squareoff value (your target price), and the stoploss price.

  {
      "variety": "ROBO",
      "price": "1000",
      "squareoff": "50", // Profit target is price + squareoff
      "stoploss": "10",  // Stop loss is price - stoploss
      "quantity": 100,
      ...
  }
  

  Note: The squareoff and stoploss values in the API are often specified as differentials from the entry price, not absolute values. Always check the latest API documentation.

Putting It All Together: The API Perspective

Your background in system architecture will appreciate how these concepts are mapped to a clean API. The Angel One API documentation provides a perfect reference table.

Here is a summary of the key mappings for Angel One:

Conclusion

You now have the vocabulary to command your trading bot. You can choose the right instruction based on the trade-offs between execution certainty and price control.

Key Takeaways:

• Market Order: Use for speed and certainty of execution. Pay with potential slippage.
• Limit Order: Use for price control. Pay with potential non-execution.
• Stop-Loss (SL) Order: A conditional order triggered by price, essential for risk management (exits) and breakout strategies (entries). Comes in Market (SL-M) and Limit (SL-L) flavors.
• Bracket (Robo) Order: A powerful compound order that bundles entry, profit target, and stop-loss. It is highly effective for automating self-contained intraday trades.
• API Mapping: These concepts translate directly into parameters like ordertype, variety, price, and triggerprice in the Angel One API.

Preview of the Next Lesson:

We've mentioned "slippage" and the "best available price" several times. But what determines that price? The market isn't just a single number; it's a collection of bids and offers. In the next lesson, we will dive into the bid-ask spread and see how its size and dynamics directly impact your execution price and trading costs.