An order type is an instruction to the matching engine, not a promise about the fill. The same contract can be entered or exited with a market order, a limit order, a stop, or a stop-limit — and the result can differ, especially when the market is moving quickly, is closed for a maintenance break, or gaps around a news release. This article explains those mechanics. It is not a recommendation of which type to use, and it is not a claim that a stop will cap your loss at a chosen price.
Platform menus use slightly different labels. Confirm what your platform will send before you rely on a setting.
Market orders
A market order is an instruction to buy or sell now at the best available price. In a liquid, two-sided book, the fill is usually close to the last price you saw. In a thin book, or when the quote is moving, the fill can be worse than that last price. That difference is slippage. A market order does not guarantee a price. It seeks a fill.
Market orders are often used when getting filled matters more than a specific tick. They are a poor fit if the market is halted, if the contract is in a daily limit, or if you are sending the order when the book is empty or clearly one-sided. In those cases there may be no fill, or a fill far from the price you had in mind.
Limit orders
A limit order is an instruction to buy at a specified price or better, or to sell at a specified price or better. “Or better” means a buy limit can fill at the limit or lower, and a sell limit can fill at the limit or higher. A limit order is not guaranteed to fill. If the market never trades at your price, the order can sit unfilled while the contract moves away from you.
A buy limit placed above the current market, or a sell limit placed below it, can behave like a marketable order and fill immediately, possibly at a better price than the limit. A limit placed away from the market waits. If you wanted a stop and you placed a standing limit instead, you may not be in or out when you expected.
Stop orders
A stop order (sometimes labeled a stop-market) becomes a market order when the contract trades at, or in some systems is bid or offered through, the stop price. The trigger is not the fill. After the stop is elected, the order seeks a fill at the then-available market. In a quiet tape, that fill may be close to the stop. In a gap — overnight, over the daily maintenance break, at the Sunday evening reopen, or around a scheduled release — the next available price can be well beyond the stop.
That is the main misunderstanding. A sell stop at 5,000.00 on a long E-mini S&P 500 position does not guarantee an exit at 5,000.00. If the contract reopens at 4,980.00, the stop can be elected and filled near 4,980.00, or worse, before costs. The same is true in metals and crude, which also trade nearly around the clock with a daily break. A stop is a plan, not a cap.
Exchange price limits and trading halts can also prevent a fill when you want one. If trading is halted or the contract is locked at a limit, a marketable order may not be executable until the market reopens or the limit is expanded, under the rules then in effect.
Stop-limit orders
A stop-limit becomes a limit order when the stop is triggered, not a market order. You specify a stop (the trigger) and a limit (the worst price you will accept). If the market gaps through both prices, the order may be elected and then not fill, because there is no trade at or better than your limit. You can be left with the original position in a market that has already moved through your planned exit.
Traders sometimes prefer a stop-limit to avoid a distant market fill. The trade-off is the risk of no fill at all. Neither type is “safer” in every case. They fail in different ways.
Other instructions you will see
Platforms may also offer:
- Stop with protection or similar exchange or platform features that add a limit cap to a stop. The exact behavior is product- and venue-specific. Read the description; do not assume it is a guaranteed price.
- Trailing stops, which move the stop as the market moves in your favor, under rules the platform defines. The trail does not remove gap risk.
- Good-till-canceled (GTC) or day time-in-force. A day order typically expires at the end of the session the platform uses; a GTC order can remain until you cancel it, it fills, or the contract expires. Confirm whether “day” means the cash-session close or the Globex day. An order left working over a weekend or a maintenance break can be elected at the reopen.
- One-cancels-the-other (OCO) brackets that link a profit-taking limit and a stop, so a fill on one cancels the other. If the stop fills beyond the stop price, or if one leg is rejected, check that the other leg was actually canceled.
None of these features change the underlying point: instructions can fail when the book is empty, the market is halted, or the next print is far from the last one.
Position size still comes first
A worse-than-expected fill hurts more when the position is large. Work backward from a loss you can tolerate, in dollars, and from the contract’s tick value, as described in Margin and Leverage in Futures and in the contract guides for E-mini S&P 500, micro metals, and crude oil. Adding contracts because a stop “would” keep the dollar loss small is circular, because the stop may not be filled at that price.
Hypothetical example (for illustration only — not a recommendation of an order type, a stop distance, or a size): Suppose you are long one Micro Gold contract and you place a sell stop $10.00 an ounce below your entry. A $10.00 decline is $100 on one MGC contract (10 ounces × $10), before costs. If the market gaps $20.00 through the stop over the maintenance break, the market order that the stop becomes could be filled around a $200 loss instead, before costs — or, with a stop-limit that is also $10.00 below the entry, you might not be filled at all. This is a teaching sketch of gap risk, not a typical result.
Scheduled economic releases, described in Reading the Economic Calendar, are a common setting for that kind of gap. So is expiration, when volume is migrating and you still have a working order in the old month. See Contract Rollover.
How to practice order types
A simulated account will not reproduce every live fill, but it is a reasonable place to send a limit, a stop, and a stop-limit in a quiet session and again around a scheduled number, and then read the resulting ticket.
ProFuturesTrader offers a 28-day no-cost demo in a simulated environment, with charts and real-time market data, on desktop or iOS: profuturestrader.com/demo. Featured platforms include ProFuturesTrader by CQG, TradingView, and MetaTrader 5, among others: profuturestrader.com/platforms. Features and fees can change. Demo accounts use simulated funds. Demo results do not reflect real trading and are not indicative of future results.
CQG Desktop walk-throughs are at profuturestrader.com/platform-education.