The short answer
Your stop loss did not fail the way you think. There are only four stories. It triggered and filled far from your price. It triggered and never filled. It never triggered. Or it was never there in the first place. A stop is a tripwire that sends an order. It is not a promise about the price, and every broker says so in its own small print. Below are the seven reasons behind those four stories, each with the sentence from the broker's own page, and how to tell from your order history which one happened to you.
What does a stop loss actually do?
Less than its name suggests. FINRA's definition is the cleanest: a stop order is "an order to buy or sell a security once the price of the security reaches a specified price," and when it does, "the order automatically turns into a market order and is executed as soon as possible at the current market price."
Read that twice. The stop does one thing: at your price, it sends a market order. A market order means "sell now, to whoever is there, at whatever they pay." So a stop at $2.00 is not "sell at $2.00." It is "when it gets to $2.00, start selling."
Think of a smoke alarm. It tells you there is a fire. It does not carry you out of the building.
| The story | What you see in your history | Which reason |
|---|---|---|
| It triggered, and filled far away | A fill, at a worse price than your stop | 1 |
| It triggered, and never filled | A triggered order still open, or canceled unfilled | 2 |
| It never triggered | The order still working, untouched | 3, 4, 5 |
| It was never there | Rejected, expired or canceled before the drop | 6, 7 |
Why did my stop fill so far from my price?
Reason 1: it worked, and the market had moved. This is the story people least expect, because it feels like a broken stop when it is a working one.
Say you hold an option at $3.00 with a stop at $2.00. Bad news lands. The next price anybody will pay is $1.40. Your stop sees $2.00 has been passed, sends its market order, and you are filled at $1.40. Nothing skipped your stop. There was simply nobody standing at $2.00.
Four brokers, one message:
| Broker | In its own words |
|---|---|
| Interactive Brokers | "A Stop order is not guaranteed a specific execution price and may execute significantly away from its stop price." |
| Robinhood | "the trade may execute at a price far away from the stop price." |
| thinkorswim | "There is no guarantee that the execution price will be equal to or near the activation price." |
| Webull | "The execution price of a stop order is not guaranteed due to its market order nature." |
Robinhood adds when to expect it: "at market open or during periods of market volatility." The open is the classic one. A stock closes at $50, your stop is at $48, it opens at $44. You are sold near $44.
Why did my stop-limit never fill?
Reason 2: you asked for a price, and nobody paid it. A stop-limit has two prices. The stop wakes it up. The limit is the worst price you will accept. If the market falls through both before anyone trades with you, the order sits there, awake and useless.
Same option, stop at $2.00, limit at $1.90. It drops straight to $1.40. Your order is now an offer to sell at $1.90 in a market paying $1.40. You still own the option. You also still own the loss.
thinkorswim's page is the most honest about it: "With a stop limit order, you risk missing the market altogether. In a fast-moving market, it might be impossible to execute an order at the stop-limit price or better, so you might not have the protection you sought." Robinhood says the same thing more politely: "there is the possibility that the order will not be executed at all."
So the choice is between two bad afternoons. A stop can give you a bad price. A stop-limit can give you no exit. Know which one you placed.
One Webull detail worth knowing before you need it: its help page lists the order types for options as Market, Stop Limit, Take-Profit/Stop-Loss, Trailing Stop and Limit. A plain "Sell Stop" is on its list for stocks and for futures, and not on the options list.
Why didn't my stop trigger when the price hit it?
Three reasons, and the first one is sneaky.
Reason 3: the price you saw is not the price your broker watches. A chart draws one number. A market has at least three: the last trade, the bid (what buyers will pay) and the ask (what sellers want). On a thin option those can be far apart, so a spike on your chart may not be the thing your stop is looking at.
Interactive Brokers says this openly: "IBKR's default trigger method for stop orders can differ depending on the type of product (e.g., stocks, options, futures, etc.)," and customers "may use IBKR's default trigger methodology or configure their own." It also says it "may simulate certain order types on its books," which means the stop may be watched by IBKR and not resting at the exchange. This guide does not say which price each broker uses for options, because the pages that would settle it for IBKR could not be opened, and the pages read for the other three do not say. Ask your broker one question: what does my option stop trigger on.
Robinhood warns about the same gap from the other side: the price displayed is "the last trade price," and "not the price at which shares are currently available."
Reason 4: the market was closed. Robinhood: a stop is "executed at the best price currently available during market hours only." Webull says its conditional orders "work only during regular trading hours." A stock can fall all evening while your stop sleeps. It wakes at the open, and then it is reason 1.
Reason 5: trading was halted. During a halt nothing trades, so nothing triggers. Robinhood: "new or existing orders will not be processed until the market reopens or the trading halt is removed," and "This also applies to options orders." When trading resumes it can be at a very different price. Reason 1 again.
Why did my stop loss disappear?
Reason 6: it expired. FINRA: day orders "expire at the end of the trading day if they aren't executed." If you set a stop as a day order on Monday, on Tuesday you have no stop. Good-til-canceled is the setting that survives the night, and even that has an end: Robinhood's page gives 90 days for options orders.
Reason 7: it was rejected or canceled, and you did not notice.
- Rejected at the door. A sell stop goes below the price. Put it above and Robinhood rejects it, along with any stop "that would execute immediately." The Robinhood guide has the table, and the IBKR one has the messages.
- Canceled with its group. thinkorswim describes an OCO like this: "Two orders are placed simultaneously; if one order is executed, the other is canceled." Take profit on part of the position and, depending on the settings, the stop can go with it. How that happens in TWS is its own guide.
- Not an order your broker takes. thinkorswim says trailing stops "are accepted only for stocks that trade on NASDAQ, NYSE, and AMEX." If the trailing stop you thought you had on an option is not in your orders list, that is why. What thinkorswim does offer for a stop on an option is its own guide.
- It was in your head. A mental stop triggers when you do. No broker page covers this one, and no broker page needs to.
Every way out of a position in Trader Workstation, with what each does to the stop under it, is on one page, each marked documented, reported or untested.
How do I find out which one happened?
Open your order history, not your chart, and find the stop.
- Is it there at all? No: reasons 6 and 7. It expired, was rejected, or was canceled with its group.
- Does it say filled? Yes: reason 1. Compare the fill price with your stop price. That gap has a name, slippage, and it is what a stop costs in a fast market.
- Does it say triggered, with no fill? Reason 2. It was a stop-limit.
- Is it still working, untouched? Reasons 3, 4 and 5. Check the time (was the market open), the symbol (was it halted), and then ask your broker what the stop watches.
Where Degen Pro fits
Only for part of this, and only on one broker. Degen Pro is a Mac app for Interactive Brokers. The stop is a real order at the broker and the app will not loosen it; if you cancel it by hand it puts it back and counts the attempt, on the settings where it holds the stop. That covers the stop that quietly went missing. It does not cover reason 1: a real order at the broker still fills at whatever the market pays. It gives no signals, opens nothing you did not choose, and needs Trader Workstation on a Mac. What makes a stop hold at IBKR is in setting a stop loss on IBKR that actually fires. What it does and costs is on the front page.
Before your next trade
- Know whether your stop is a stop or a stop-limit. One can fill badly. The other can not fill.
- Size the trade for a fill worse than your stop, because one day it will be.
- Check the time in force. A day order is gone tomorrow.
- After you place it, look for it in the orders list. Rejections are quiet.
- After any partial exit, look again. The stop may have left with its group.
- Ask your broker what an option stop triggers on. It is one message, and it is worth it.
None of this is investment advice. Trading involves risk of loss, and a stop reduces that risk only when it is there, awake, and somebody is on the other side.