Order types, and what each one costs you
Every order type trades one certainty for another. A market order guarantees you get in but not at what price. A limit order guarantees the price but not that you get in at all. Everything else is a combination of those two ideas.
Market order
“Fill me now, at whatever is available.” You are certain to be in the trade; you are not certain what you paid. In liquid conditions the difference is the spread. Around a data release, in a thin market or on a gap, it can be much worse — this is slippage, and it is the price of urgency.
Use it when being in the trade matters more than the exact entry, and when you are exiting a position that has gone wrong. Getting out is one of the few moments where paying for certainty is usually correct.
Limit order
“Fill me at this price or better, otherwise do not fill me.” You control the price and give up control of participation. If the market never trades back to your level, you simply miss the move — and the trades you miss are systematically the ones that ran hardest in your direction.
That asymmetry is worth remembering: a limit-only approach quietly selects for the weakest version of every idea.
Stop order
“Do nothing until price trades at this level, then send a market order.” It is used two ways. As an exit it is the stop loss — the automated version of admitting the idea failed. As an entry it buys strength: you only participate once price has proven it can reach the level.
Because it becomes a market order when triggered, it inherits market-order behaviour: the fill can be worse than the trigger, sometimes much worse on a gap. A stop is an instruction to leave, not a promise about the price you leave at. Your protection against that gap is position size, not the stop itself.
Stop-limit order
“At this trigger, place a limit order at that price.” It protects you from a terrible fill — and it can leave you in a losing position while price runs past your limit without filling. As an exit, this is the worst possible outcome: the protection you thought you had did nothing. Most traders should not use stop-limit orders for exits.
Time in force
- Day — expires at the end of the session. Sensible default for intraday work.
- GTC (good till cancelled) — lives until you remove it. Audit these; forgotten orders fire weeks later into a market you no longer understand.
- IOC / FOK — fill immediately (partially or entirely) or cancel. Relevant when size is large relative to available liquidity.
The practical rule
Choose the order type from what you are protecting. Protecting participation: market. Protecting price: limit. Protecting against your own hesitation: stop. And whatever you choose for the entry, keep the exit simple — complexity at the exit is where losses turn into disasters.