Market price protection in ATO (Alert Triggers Order)
Market price protection in an Alert Triggers Order (ATO) is the control on Kite that converts the market order placed by the ATO into a limit order if the price moves outside a set protection range, so an order placed automatically when an alert fires cannot fill at a freak price far from the market. An ATO is a Zerodha feature, launched on 16 September 2024, that links a basket of orders to a Kite alert and sends those orders to the exchange the moment the alert is triggered, without further action from the trader.
This entry explains why an automatically placed order needs price protection, the exact percentage bands applied across equity, futures and options, how the band is computed and how unfilled quantity is handled, and which segments and validity rules apply. Because an ATO market order behaves like an at-the-open order when an alert fires in a fast market, it sits alongside the order-window market protection and the market-to-limit behaviour in the pre-open as the three places a market order on Kite is bounded rather than left open-ended.
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What an ATO is and why protection matters
An ATO links one or more orders to an alert. Alerts can be built on price, on open-high-low-close levels, on volume, on open interest, and other conditions. The older Kite alerts feature only notified you and left the order placement to you; an ATO removes that step and places the linked orders automatically the instant the condition is met. You might set an alert on the Nifty 50 at a level and link a basket of orders to fire when it is reached.
That automation is also the risk. The order goes to the exchange at the precise moment a price level is breached, which is often a moment of fast movement and a thinner book. A plain market order placed then could sweep the book to a freak price before a human could react. Market price protection exists for this reason: all market orders in an ATO use it, so the auto-placed order is bounded by a percentage band rather than left to fill at any price the book offers. This is the “at-the-open” character of an ATO order, it executes the instant the trigger opens, and it is why the band is built into the feature rather than left optional.
The protection band by instrument and price
The band is a percentage of the last traded price and steps down as the price rises, identical to the order-window table. The current bands are below.
| Security | Last traded price | Protection band |
|---|---|---|
| Equity and futures | Under Rs 100 | 2 per cent |
| Equity and futures | Rs 100 to Rs 500 | 1 per cent |
| Equity and futures | Above Rs 500 | 0.5 per cent |
| Options | Under Rs 10 | 5 per cent |
| Options | Rs 10 to Rs 100 | 3 per cent |
| Options | Rs 100 to Rs 500 | 2 per cent |
| Options | Above Rs 500 | 1 per cent |
Options carry wider bands at each tier because option premiums swing more in percentage terms than the underlying, so a band as tight as the equity one would convert ordinary fills into resting limit orders too often.
How the band is applied
When an ATO places a market order, the system calculates a protection range from the current price, tries to fill immediately within it, then converts any unfilled quantity to a limit order at the protection price if the market moves outside the range. The intent is stated plainly in Zerodha’s documentation: the client does not pay more than a specified price for a buy order, or receive less than a specified price for a sell order. A buy is allowed to fill up to the band above the market; a sell down to the band below it.
A worked case: a stock at Rs 90, an ATO buy for 100 shares. Because the price is under Rs 100, the 2 per cent band applies, and the protection limit is Rs 91.80. Shares fill at Rs 91.80 or below, and any unfilled quantity stays open as a limit order at Rs 91.80. The order never pays above Rs 91.80, whatever the book does above that level when the alert fires.
Validity, supported segments and corporate-action handling
ATO orders default to Day validity and are cancelled if not executed by the end of the trading day, which you can change in the order window. ATOs can be placed only in NSE equity, NSE F&O, BSE equity, and BSE F&O segments, so the feature does not extend to commodity or currency in the same way. When an alert triggers, you receive a push notification and an email. One safeguard sits ahead of execution: alerts are auto-disabled if a corporate action changes the price by more than 2 per cent, so a split or bonus that resets the price does not fire a stale alert into an order at the wrong level. The notification mechanics are covered in Kite alert notifications .
ATO protection versus order-window and pre-open protection
The percentage band is the same across the order-window feature and the ATO feature; what differs is when it applies. Order-window market protection applies to an order you place yourself with Advanced, then Market protection turned on. ATO protection applies to the order the alert places for you, automatically, and is always on for an ATO market order. The third related mechanism is the exchange pre-open session, where a market order entered for the pre-open is discovered at the equilibrium price and, if no opening price is discovered, carried over at the previous close; the market-to-limit-in-the-pre-open behaviour is the exchange-side counterpart to the broker-side bands described here. Together these three keep a market order on Kite from filling at an unbounded price, whether you place it by hand, through an alert, or into the opening auction.
When the band still leaves slippage
The protection band caps how far from the current price an ATO order can fill; it does not guarantee the price you expected when you set the alert. If the market gaps through your alert level between the trigger firing and the order reaching the exchange, the order fills at the band around the new price, not the price at which the alert was set. And, as with all market protection, the band is anchored to the last traded price, so a freak print that becomes the LTP shifts the band with it. For a hard price ceiling or floor, set the linked order as a limit order at a level you choose rather than a market order, accepting that a limit may not fill if the price runs past it.
See also
- Kite alerts
- How to add and customise alerts on Kite
- Alert-triggered order on Kite
- Kite alert notifications
- Market price protection on the Kite order window
- Market-to-limit in the pre-open
- Pre-open session orders on Zerodha
- How to fix a market order executed as a limit order
- Why a limit order is executed at market
- Market order on Kite
- Limit order on Kite
- SL-M order on Kite
- Trigger vs limit price
- Order validity types
- Disclosed quantity orders
- GTT order on Zerodha
- How to place a GTT order on Kite
- Basket order on Kite
- Kite nudges
- How to cancel orders quickly on Kite
- Circuit limits / price bands
- Why limit orders far from LTP are rejected
- Price reasonability range (PRR)
- Kite (Zerodha)
- Zerodha
- National Stock Exchange
- Bombay Stock Exchange
- SEBI
External references
- Zerodha support: What is market price protection in Alert Triggers Order (ATO)?
- Zerodha: Introducing the Alert Triggers Order (ATO) feature on Kite
- Zerodha support: What is Market protection on the order window?
- NSE India: pre-open session
- BSE India
References
- Zerodha support, What is market price protection in Alert Triggers Order (ATO)? (as of 21 June 2026).
- Zerodha, Introducing the Alert Triggers Order (ATO) feature on Kite, 16 September 2024.
- Zerodha support, What is Market protection on the order window? (as of 21 June 2026).
- NSE India, equity market pre-open session, order types and equilibrium price discovery.