Order Types and Trading Basics
About This Lesson
Every trade you place starts with an instruction: buy or sell, at what price, and under what conditions. The order type is that instruction. Pick the wrong one and you either pay more than you meant to or watch a trade you wanted slip away. This is a high-yield topic, and the patterns here repeat in trading scenarios throughout the rest of the course, so it is worth knowing cold.
What you'll cover
- Market orders, which guarantee execution but not price
- Limit orders, which guarantee price but not execution, and where they rest on the book
- Stop and stop-limit orders, and the situations each is built for
- Buy stop versus sell stop placement, above or below the current price
- Day orders, GTC orders, and the qualifiers AON, FOK, and IOC
- Bid, ask, and spread, and how a firm gets paid for filling your order
The single highest-yield rep is stop placement: a buy stop sits above the market, a sell stop sits below it. Lock that in and you will pick up several points on test day.
Market and Limit Orders
Before you can place a single trade, you have to answer two questions: how fast do you need it done, and how much do you care about the price? Those two priorities pull against each other, and the two most basic order types sit at opposite ends of that tension.
A market order says fill me right now, at whatever the market is offering. It guarantees execution but not price. In a liquid stock the fill will be close to what you saw on the screen, but in a thin or fast-moving market it can drift. The bargain is simple: you give up control over price in exchange for certainty that the order gets done.
A limit order flips that bargain. It says fill me only at my price or better, which guarantees the price but not the execution. A buy limit sets the most you are willing to pay; a sell limit sets the least you are willing to accept. If the market never reaches your number, the order simply waits, and it may never fill at all.
Where you set that number matters, and it is a favorite exam point. A buy limit is placed at or below the current price, because you are trying to pay no more than your limit. A sell limit is placed at or above the current price, because you want at least your limit. So a buy limit at $48 while the stock trades at $52 does not execute right away. It rests on the order book and fills only if the price falls to $48 or lower. A limit priced away from the market is perfectly valid; it is just a standing instruction waiting for the market to come to it.
How long the order lives
Every order also carries a duration. A day order expires at the close if it has not filled, and unless you say otherwise, that is the default. A good-til-canceled (GTC) order stays working across sessions until it executes or you cancel it.
Long and short
Two words describe which direction you are betting. You are long when you own a security and want the price to rise, the ordinary bullish position. You are short when you have sold borrowed shares hoping to buy them back cheaper later, a bearish position that profits when the price falls. Keep these straight, because the next section on stop orders leans on knowing whether a position is long or short.
Stop and stop-limit orders build directly on the market and limit orders you just met. They are conditional: nothing happens until a trigger price is reached. We take those up next.
A market order guarantees execution but not price. A limit order guarantees price but not execution. If you need to get in or out immediately, use a market order. If price matters more than speed, use a limit order.
Which type of order guarantees execution but does NOT guarantee a specific price?
An investor enters a buy limit order at $48. The stock is currently trading at $52. Which of the following is true?
Stop and Stop-Limit Orders
A stop order is a trade that waits in the wings. You name a trigger price, and nothing happens until the market touches it. The moment it does, the stop elects and turns into a live market order, which means execution is guaranteed but the fill price is not. That last detail is where most people lose the point, so hold onto it.
Sell stop orders
A sell stop is placed below the current price and triggers when the stock falls to or through that level. Picture a stock you bought at $50 that has climbed to $60. You place a sell stop at $55 to lock in most of the gain. If the stock slides back to $55, the stop becomes a market order and sells you out near there, protecting your profit on the way down. The same tool caps a loss: a sell stop set below your purchase price gets you out before a decline runs away from you.
Buy stop orders
A buy stop is the mirror image. It sits above the current price and triggers when the stock rises to or through that level. Its classic use is protecting a short position: if you sold borrowed shares at $50 and the price starts climbing against you, a buy stop at $55 caps the damage by buying the shares back before the loss grows. Traders also use buy stops to enter on an upside breakout, stepping in only once the stock proves it can push past a certain price.
Stop-limit orders
A stop-limit changes one thing: when the trigger is hit, the order becomes a limit order instead of a market order. That hands you back control over price, but it brings back the limit-order weakness. If the market gaps straight through your limit in a fast decline, the order may never fill, and you can be left holding the very position you were trying to exit. You trade the certainty of getting out for the certainty of a price.
When a sell stop order triggers, it becomes a market order, not a guaranteed sale at the stop price. In a fast-declining market the execution could be significantly below the stop price.
A stop-limit solves this by converting to a limit order at the stop, but introduces a new risk: if the price gaps past the limit, the order never fills.
SIE question pattern: "Which order guarantees execution but not price?" → Stop order.
"Which order guarantees price but not execution?" → Limit order or stop-limit order.
An investor places a sell stop order at $45 on a stock currently trading at $50. The stock drops rapidly to $43. At what price will the order most likely execute?
Bid, Ask, and the Spread
At any moment, a security has two prices, not one. The bid is the highest price a buyer is currently willing to pay, and the ask, also called the offer, is the lowest price a seller is willing to accept. From your seat as a customer, the rule is short: you sell at the bid and buy at the ask. The market always quotes you the price that is worse for you, which is exactly how the dealer in the middle gets paid.
The gap between the two is the spread, and it is the market maker's compensation for standing ready to trade. Say XYZ is quoted 25.10 bid / 25.25 ask. A market order to buy fills at the $25.25 ask; a market order to sell fills at the $25.10 bid. That $0.15 difference is what the dealer earns for providing liquidity, taking the other side of your trade whether or not another customer happens to be ready at that instant.
Who maintains the quotes
On Nasdaq, that role belongs to market makers: dealers who post firm bid and ask quotes in specific securities and trade out of their own inventory. Several market makers can compete in the same stock, and that competition tends to tighten the spread. On the NYSE, the job falls to a Designated Market Maker (DMM), the role formerly called the specialist, who is assigned to specific securities and charged with keeping the market in them fair and orderly.
Whatever the venue, a quote is a promise. A dealer who refuses to trade at a price it has publicly quoted is backing away, and that is a violation. The quote you see is the quote you can hit.
Practice order types, bid-ask spreads, and markup/markdown calculations.
Order Qualifiers and Trade Capacity
Beyond the basic order types, a customer can attach instructions that control exactly how an order is allowed to fill. These qualifiers show up as a cluster on the exam, and the cleanest way to keep them straight is by what they demand: all of it, all of it right now, or as much as possible right now.
- All-or-None (AON): fill the entire order or none of it. It does not have to fill immediately, so an AON order can sit and wait until the full size is available. It is not displayed on the order book.
- Immediate-or-Cancel (IOC): fill as much as you can this instant and cancel whatever is left. Partial fills are fine.
- Fill-or-Kill (FOK): the strictest of the three. Fill the entire order immediately or cancel all of it. Think of it as IOC and AON combined: everything, right now, or nothing.
- Not Held: hands the floor broker discretion over the timing and price of the fill. The customer agrees not to hold the broker responsible if the execution price moves.
Acting as agent or as principal
How a firm earns money on a trade depends on the capacity it takes. When a broker-dealer acts as an agent (broker), it stands between buyer and seller, arranges the trade, and charges a commission for the service. When it acts as a principal (dealer), it trades from its own inventory: it adds a markup when it sells a security to a customer and takes a markdown when it buys a security from a customer. The direction is easy to remember once you see that the firm always comes out ahead by that amount, so the customer pays a little more when buying and receives a little less when selling.
Two rules ride along with this. A firm cannot charge both a commission and a markup or markdown on the same transaction; it is one or the other, set by the capacity it took. And a riskless (or simultaneous) principal trade is the in-between case: the firm buys a security only after it already holds the customer's order, so it technically acts as principal but carries almost no inventory risk.
A broker-dealer acts as principal in a transaction with a customer. The broker-dealer's compensation is called:
A broker-dealer buys shares from a customer at $24.50 and had previously quoted $25.00 on the bid. The firm earned:
Chapter Essentials
Two priorities drive every order. A market order guarantees execution but not price; a limit order guarantees price but not execution, and it rests on the book until the market reaches it. Placement is directional: a buy limit sits at or below the current price and a sell limit at or above it. Stop orders are conditional. A sell stop sits below the market to protect a long position, a buy stop sits above it to protect a short or catch a breakout, and a triggered stop becomes a market order (execution, not price). A stop-limit instead becomes a limit order, trading the certainty of getting out for the certainty of a price.
On pricing and pay, you buy at the ask and sell at the bid, and the spread between them is the market maker's compensation for providing liquidity. How a firm earns on a trade follows its capacity: as agent it charges a commission, and as principal it adds a markup when selling to a customer or takes a markdown when buying from one, never both on the same trade. Mind the duration and fill rules too: a day order dies at the close while a GTC order works until filled or canceled, and FOK means the whole order fills immediately or none of it does.
Pacing, elimination, flagging, and the test-taking tactics that move your score.
The reliable gotchas in this chapter:
• Stop placement is reversed from intuition. A buy stop goes above the market and a sell stop goes below it. Questions love to flip this and wait for you to agree.
• Limit placement is the opposite of stops. A buy limit sits at or below the market and a sell limit at or above it. A buy limit below the current price is valid and simply rests on the book.
• Know which side you trade on. Customers buy at the ask and sell at the bid, never the reverse.
• A triggered stop is a market order. It guarantees execution, not price, so in a fast move the fill can land well past the stop. A stop-limit fixes the price but may never fill.
• Commission or markup, not both. A firm charges a commission as agent or a markup or markdown as principal on a given trade, but never both at once. A markdown is what the firm keeps when it buys from a customer below the market.
Test yourself with exam-style questions on this topic.