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Order Types Reference

A reference table of the order types available to algorithmic traders, comparing fill certainty against price certainty, when each is used, its NSE/India specifics, and its risks.

Order Types: Every order type trades off fill certainty against price certainty. A market order guarantees a fill but not the price; a limit order guarantees the price (or better) but not the fill. Stop orders are conditional — an SL-M becomes a market order when a trigger is hit (fill certain, price not), while an SL/stop-limit becomes a limit order (price capped, fill not). Bracket and cover orders are broker-side wrappers that attach a stop-loss (and, for brackets, a target) to an entry to automate risk. GTT (Good Till Triggered) is a longer-lived resting trigger. On the NSE, order behaviour is shaped by circuit limits, tick size, and the fact that several of these convenience products are broker features rather than native exchange order types, so their exact rules vary by broker.

This reference summarises the order types a systematic trader routinely uses on Indian markets. The governing trade-off is always the same: certainty of getting filled versus certainty of the price you get. For deeper treatment see Market orders, Limit orders, and Stop orders.

The core trade-off

You cannot have both perfect fill certainty and perfect price certainty at once. Choosing an order type is choosing which one you are willing to give up for a given trade. Aggressive, must-be-in-now decisions favour fills; patient, price-sensitive decisions favour limits.

Order typeWhat it doesFill vs price certaintyWhen usedIndia / NSE noteKey risks
MarketExecutes immediately at the best available price(s).Fill certain; price not.When being in the trade matters more than the exact price, and the book is liquid.On illiquid strikes or wide spreads the fill can be far from the last price; NSE applies price protection but slippage still bites.Slippage; poor fills in thin books; can sweep multiple price levels.
LimitExecutes only at your specified price or better.Price certain; fill not.When price matters and you can wait, or to provide liquidity.Must respect NSE tick size; rests in the order book and may sit unfilled if price moves away.Non-fill or partial fill; missing the move entirely if price runs.
Stop-Loss Market (SL-M)Dormant until the trigger price is hit, then becomes a market order.Fill certain once triggered; price not.To exit a losing position reliably regardless of price.Some brokers/segments restrict SL-M in options; check current NSE and broker rules.Gaps through the trigger cause a fill well beyond it; slippage on the exit.
Stop-Limit (SL)Dormant until the trigger, then becomes a limit order at your set limit price.Price capped; fill not certain.When you want a stop but refuse to accept an arbitrarily bad exit price.Requires both a trigger and a limit that respect tick size; NSE conventions on trigger direction apply.Price can jump past the limit, leaving the stop unfilled and the position open.
Bracket (BO)An entry with an attached target and stop-loss placed together as one bracket.Depends on the legs; automates the exit pair.Intraday, to define risk and reward up front and automate both exits.A broker product (often intraday, auto-squared-off), not a native exchange order; availability and rules vary and some brokers have curtailed it.Broker-specific behaviour; auto square-off timing; leg-handling on gaps.
Cover (CO)An entry paired with a compulsory stop-loss, enabling higher intraday leverage.Entry fill per its type; stop is mandatory.Intraday directional trades where a built-in stop is acceptable.A broker product tied to intraday margin rules; the mandatory stop defines the margin. Rules vary by broker.Forced stop placement; gap-through slippage; auto square-off.
GTT (Good Till Triggered)A long-lived resting instruction that places an order when a trigger condition is met, valid for a long period.Trigger then behaves per the underlying order (usually limit).For entries or exits you want to persist over days/weeks without a live process.A broker-side feature (not a standing exchange order); it fires an order to the exchange only when triggered, subject to a validity cap.Not guaranteed to fill on trigger; broker-side, so an outage can affect it; corporate actions can invalidate levels.

Broker product vs native exchange order

Market, limit, and stop orders are native exchange order types. Bracket, cover, and GTT are broker-built convenience products layered on top. That distinction matters for an algo: native orders behave consistently, whereas broker products have provider-specific rules, availability changes, and square-off timings. Always read your broker's current API documentation rather than assuming behaviour.

Choosing an order type in an algo

  • Entering a liquid, fast-moving instrument where you must be in: a market order accepts slippage for certainty.
  • Entering a price-sensitive or illiquid instrument: a limit order protects price but may not fill — handle the non-fill case in code.
  • Protecting a position: an SL-M guarantees the exit fires; an SL/stop-limit caps the price at the risk of not exiting on a gap.
  • Automating risk on entry: bracket or cover orders bundle the stop, but tie you to broker-specific behaviour and intraday square-off.
  • Persistent conditional orders: GTT resting triggers avoid keeping a process live, at the cost of broker-side dependence.

Whatever you choose, your execution engine and OMS must handle rejections, partial fills, and trigger-not-hit states — not just the happy path.

SL-M vs SL in one line

An SL-M guarantees you exit but not at what price (it becomes a market order on trigger). An SL / stop-limit guarantees the worst price you will accept but not that you exit at all (it becomes a limit order). Pick SL-M when the priority is definitely getting out; pick SL when you would rather stay in than exit at a terrible price.

Related concepts

See Partial fills, Slippage, Liquidity, and Execution quality for the mechanics that determine how each order type actually behaves.

Frequently asked questions

What is the difference between a market order and a limit order?
A market order executes immediately at the best available price, so the fill is certain but the price is not. A limit order executes only at your specified price or better, so the price is certain but the fill is not — it may rest unfilled if the market moves away. The choice is fill certainty versus price certainty.
What is the difference between SL-M and SL orders?
Both are stop orders that lie dormant until a trigger price is hit. An SL-M then becomes a market order, guaranteeing the exit but not the price. An SL (stop-limit) becomes a limit order at a price you set, capping how bad the exit can be but risking that it never fills if price jumps past the limit.
What is a bracket order?
A bracket order is a broker product that places an entry together with an attached target (take-profit) and stop-loss, so both exits are automated the moment you enter. It is typically an intraday product with auto square-off. Because it is broker-built rather than a native exchange order, its exact rules and availability vary by broker.
What is a cover order?
A cover order pairs an entry with a compulsory stop-loss, and because the risk is bounded by that mandatory stop, brokers often allow higher intraday leverage on it. Like the bracket order, it is a broker product tied to intraday margin rules and auto square-off, so behaviour differs between brokers.
What is a GTT order on the NSE?
GTT stands for Good Till Triggered. It is a broker-side resting instruction that fires an order to the exchange only when a trigger condition is met, and it stays valid for a long period (subject to a cap). It lets you set conditional entries or exits without keeping a live process running, but it is broker-dependent and not guaranteed to fill.
Why do market orders cause slippage?
A market order takes whatever prices are available in the order book until it is filled. In a liquid instrument the best bid and offer are close, so slippage is small. In a thin book — an illiquid option strike, for example — the order can sweep through several price levels, and the average fill can be well away from the last traded price.
Are bracket and cover orders real exchange order types?
No. Market, limit, and stop orders are native exchange order types, but bracket, cover, and GTT are convenience products built by brokers on top of them. This matters for automation because broker products carry provider-specific rules, can be modified or withdrawn, and have their own square-off timings, whereas native orders behave consistently.
Which order type is safest for exiting a losing trade?
For a reliable exit, an SL-M is safest because it guarantees the position is closed once the trigger is hit, accepting whatever price the market offers. An SL (stop-limit) can leave you stuck in a losing position if price gaps past your limit. The trade-off is that SL-M can fill far beyond the trigger on a gap.
Can a limit order guarantee I get filled?
No. A limit order only executes at your specified price or better, so if the market never trades at that level — or trades through it too fast — the order can remain partly filled or entirely unfilled. Any algorithm using limit orders must explicitly handle the non-fill and partial-fill cases rather than assuming execution.

Last reviewed 11 July 2026. Educational content only — not investment advice.

Educational content only — not investment advice. See our Risk Disclosure and Methodology.