Market vs. Limit vs. the Other Order TypesStart here
The order type is a decision about which risk you accept: paying too much, or not trading at all. Everything else in execution follows from that one trade-off.
The single trade-off
- A market order accepts price risk to eliminate execution risk. You will trade; you do not know exactly at what.
- A limit order accepts execution risk to eliminate price risk. You know the worst price you will pay; you do not know whether you will trade at all.
- There is no third option. Every other order type is a rule for switching between these two, and each of them inherits the weakness of whichever it turns into.
- Which risk is worse depends on the position, not on preference. That is the whole decision.
The main types, and what each actually risks
| Type | What it does | What can go wrong |
|---|---|---|
| Market | Trades now at the best available price | Thin book, wide spread, a bad print in a fast market |
| Limit | Trades only at your price or better | Never fills; or fills only when someone informed wants the other side |
| Stop (market) | Becomes a market order once a level trades | Gaps straight through — you get the price after the move |
| Stop-limit | Becomes a limit order at a level | Fails to fill in exactly the crash it was meant for |
| Auction / at-close | Trades in a scheduled auction | Concentrated price, but no control over the level |
Why a limit order has a hidden cost
- A resting limit order is a free option you wrote. You have given the market the right, not the obligation, to trade with you at your price for as long as it sits there.
- It gets exercised adversely. Your buy limit fills when someone is keen to sell — which correlates with them knowing something. This is adverse selection, and it is the mechanism behind the bid–offer spread existing at all: see market microstructure.
- The consolation is that you are also being paid: you are supplying liquidity rather than buying it, which is the good side of the trade in what liquidity costs.
- The net: limit orders are usually cheaper than market orders and not free, and the difference is smaller than the spread suggests.
Why stops fail exactly when they matter
- A stop is not a floor. It is an instruction to sell after a level trades, and in a gap there is no trade at your level — the next print is well below it.
- Overnight and weekend gaps skip the level entirely. Earnings, policy decisions and geopolitical events routinely open several percent away.
- Stop-limit is worse in the case you built it for. Adding a limit prevents a terrible fill and also prevents any fill, leaving you fully exposed in the crash.
- Stops cluster at round numbers, and a cluster of stops is a pool of forced sellers that other participants can see — one reason sharp moves accelerate through obvious levels.
- The correct conclusion is not to abandon stops but to size as though the stop might not work, which is the point the sizing playbook makes at length.
Choosing from the position rather than from habit
- Small order, liquid instrument, tight spread → market. The spread is trivial and certainty is worth more.
- Large order relative to volume → work it, or use an auction. A market order here pays impact on top of spread, and impact grows roughly with the square root of relative size.
- Illiquid instrument, wide spread → limit, patiently, inside the spread. A market order in a wide book is the most expensive routine mistake available.
- Around a scheduled event → wait. Spreads widen before announcements and normalise afterwards, and paying the widened spread is optional.
- At the open → wait a few minutes. Opening prints are frequently unrepresentative, and the first minutes carry the widest spreads of the day.
- An exit you genuinely need → market, and accept the cost. A limit order that does not fill has not protected you from anything.
The costs, quantified
- The spread calculator converts a bid–offer into basis points of notional and into an annual cost at your turnover. The annual figure is usually the surprising one.
- Compare it against your expected edge. A round trip costing 60 basis points against a position expected to earn 200 over a year spends most of the first quarter on entry and exit.
- Turnover is the multiplier. Halving the number of trades halves this cost with certainty, which is a rare thing in markets.
The checklist
- Which risk am I less able to carry — a worse price, or no trade?
- How wide is the spread right now, in basis points of my position?
- How large is my order relative to typical volume?
- Is there a scheduled event in the next few minutes or hours?
- If I am using a stop, have I sized as if it will not work?
- Do I need to trade at all today? The cheapest execution is the one not required.
Information and education only. Order types, their names and their behaviour differ between venues and brokers. This page describes general market mechanics for teaching purposes; it is not advice, not a trading strategy, and your platform's own documentation governs how its orders behave.