Market and limit orders
A market order says: deal now, at the best price available. The fill is as certain as anything in a working market; the price is not. If the quantity is larger than what is offered at the best price, the order is filled at successively worse prices until it is complete.
A limit order says: deal at this price or better, and otherwise not at all. A buy limit is placed below the current price and a sell limit above it. The price is certain; the fill is not. The market may never reach the limit, or may touch it for a moment with too little on offer to fill the order.
Stop and stop-limit orders
A stop order sleeps until the market reaches its level, and then becomes a market order. A buy stop is placed above the current price and a sell stop below it. A stop-loss is a stop order attached to an open position. Because it turns into a market order, it is filled at the next price available, which may be worse than the level chosen.
A stop-limit order becomes a limit order when it is triggered. The price is then protected, but the fill is not: in a fast fall a sell stop-limit can be triggered and left behind unfilled, with the position still open and the loss still growing.
It matters which price does the triggering. On many retail platforms a sell order is triggered by the bid and a buy order by the ask. A stop that protects a short position is a buy order, so it can be set off when the spread widens, although a chart drawn from bid prices never shows the level being touched.
Trailing stops and one-cancels-the-other
A trailing stop is a stop whose level follows the price at a fixed distance when the price moves in the position’s favour, and stays where it is when the price moves back. It never loosens.
Where the trailing is done is a practical point. On some platforms the server does it. On others the trader’s own terminal does it, by sending a changed stop each time the price advances, and it ceases when that terminal is closed or loses its connection. MetaTrader 5 works in the second way.
One-cancels-the-other, or OCO, links two orders so that when one is filled the other is cancelled. A stop-loss and a take-profit attached to the same position behave like this. As a free-standing pair, for example a buy stop above a range and a sell stop below it, OCO is offered on some platforms and not on others.
Partial fills and fill policies
An order may meet less quantity at its price than it asks for. What happens to the remainder is set by the fill policy, which goes by standard names. Which of them applies, and whether a trader may choose, depends on the instrument and on how the broker has set it up.
- Fill or kill: the whole quantity at once, or nothing.
- Immediate or cancel: fill what is available now and cancel the rest.
- Return: fill what is available and leave the rest working as an order.
Slippage and gaps
Slippage is the difference between the price expected when an order was sent and the price at which it was filled. It arises because prices move in the time an order takes to arrive, and because the quantity available at each price is limited. It can go either way. It is greatest when markets are fast or thin: at a scheduled release, at the open of a session, around the daily rollover.
A gap is a jump from one price to another with no dealing in between, most often over a weekend or at a piece of news. A stop order whose level lies inside the gap is triggered at the first price beyond it and filled there, not at its own level. A limit order whose level lies inside a gap is usually filled at the better price on the far side.
Some firms offer a guaranteed stop, which is filled at its level whatever happens, in return for a charge. Whether one is offered is a matter of each firm’s terms.
Whether an order is filled, requoted or rejected when the price has moved away while it was on its way is likewise a matter of each firm’s terms.
Time in force
Time in force says how long an order remains alive if it is not filled.
- Good till cancelled: it stays until it is filled or withdrawn.
- Day: it lapses at the end of the trading day.
- Good till date: it lapses at a stated date and time.
- Immediate or cancel, and fill or kill, are also instructions about time: the order lives for an instant.
- A pending order left working over a weekend or through a release is exposed to whatever gap occurs. An order forgotten is still an order.
A worked example: a stop, a gap and a stop-limit
Illustration · invented round figures, not market prices and not GIO4X fees
A position is long from 100, with a sell stop at 95. The planned loss is 5 for each unit held. The market closes on Friday at 97.
- Over the weekend there is news. On Monday the first price is 91.
- The stop’s level, 95, lies inside the gap. The stop is triggered at the first price and filled at about 91.
- The loss is 9 for each unit, not 5. No price between 97 and 91 ever existed to sell at.
- Had the order been a stop-limit with a limit of 94, it would have been triggered and not filled, because the market was already below 94. The position would still be open at 91, with nothing now protecting it.
A stop sets the price at which an order is sent, not the price at which the position is closed. The number of units is the one thing in the example that was fully in the trader’s hands. The example leaves out the spread.
What this page does not tell you
- Which order types, fill policies and expiry settings are available on a particular platform, instrument or account. That is read from the platform itself and the broker’s terms.
- How any broker fills stops in a gap, whether it requotes, and whether it offers a guaranteed stop. Those are in its order execution policy.
- Where to place a stop or a target. This page explains what the instructions do, not how to choose their levels.
- How an order behaves on an exchange with auctions, price limits or halts, each of which has rules of its own.
At GIO4X
GIO4X’s order execution policy is not yet published, so this page says nothing about how GIO4X fills, requotes or rejects an order, which fill policies apply to its instruments, or whether any stop is guaranteed. Those points can be asked for in writing. The Order anatomy tool shows the parts of a single order.
Questions people ask
- Does a stop-loss guarantee my maximum loss?
- No. An ordinary stop-loss guarantees that an order is sent when its level is reached. It is filled at the next price available, which in a fast market or after a gap can be some way beyond the level.
- Why was my stop triggered when the chart never reached it?
- Often because the chart is drawn from one side of the quote and the order is triggered by the other. A stop on a short position is a buy order and is commonly triggered by the ask, which rises when the spread widens even if the bid does not move.
- Is slippage always against the trader?
- No. Prices can move in the order’s favour between sending and filling, and a limit order by its nature can only be filled at its price or better. Whether favourable moves are passed on is one of the things an execution policy states.
Related pages on this site
- Order anatomyToolThe parts of one order, drawn.
- Order types, side by sideComparisonFive order types in one table, with an animated example.
- When the price gapsPlaybookThe situation, and what to check.
- Slippage on an orderPlaybookWhy the fill differed from the price on screen.
- A stop hit by a wickPlaybookBid, ask and the price that triggers.
- Market microstructurePrimerWho fills an order, and why spreads widen.
- Trade AnatomyLabsOne order followed from the click to the balance.
Tools that work the idea
The words on this page
A general explanation for study, with an invented example. Rules, costs and terms differ by country, market, provider and product, and the documents of the thing itself are what count. Educational information, not investment advice or a recommendation to trade.
GIO4X Academy · Market primers · Written 5 October 2026
https://www.gio4x.com/primers/order-types-in-depth
Printed from gio4x.com.