Stop-Loss Order
A stop order buys or sells a stock once the stop price is reached; it then becomes a market order. The fill may differ from the stop, especially in a fast market.
A stop order is an order to buy or sell a stock once the price of the stock reaches a specified price, known as the stop price. When the specified price is reached, your stop order becomes a market order. The executed price may differ from the stop, especially in a fast market. The trigger is not a fill.
Investor.gov lock: Stop Order, then a market order
The investor.gov glossary titles the page Stop Order, not stop-loss. The lock is one sentence: when the specified price is reached, the stop becomes a market order. A market order is an order to buy or sell at the current market price. The fill may not be the price you expected. That is the same disadvantage restated at the stop: a short-term fluctuation can activate the stop, and in a fast-moving market the print can differ from the stop price.
Until the stop price is reached, nothing has been sold or bought. After it is reached, you have a market order in the live book. The stop price was the trigger, not the fill. Through a gap, a trading halt resume, or a thin Early book, those available prices can be through the stop. This page does not invent typical gap percents.
Some brokers also offer a stop-limit ticket, a different instruction that, after a trigger, becomes a limit order rather than a market order. That is not the investor.gov definition, and this page does not claim investor.gov defines a stop-limit fill. TODO:VERIFY that ticket’s fill, trigger convention, and default with your firm. Do not read this glossary row as a stop-limit encyclopedia.
Gaps can print through the stop
A gap is a print away from the prior print, often at a session boundary, an auction, or a halt resume. Early 4:00 a.m. ET versus Early 7:00 a.m. ET is an exchange split (NYSE Arca Early 4:00 a.m.; NYSE / NYSE American Early 7:00 a.m.), not a broker clock. Overnight 9:00 p.m.–4:00 a.m. ET is planned for December 6, 2026, not live as of 2026-08-25. Cite U.S. session hours 2026. Broker windows are not venue clocks. Broker overnight is ATS access, not exchange overnight.
If the last Core print was $53.00 and the next print is $50.80, a sell stop at $51.50 has already been passed. Because the stop became a market order, it takes available size near $50.80. That is the fill. It is not a promised print at $51.50. Cboe C1 equity-options Global Trading Hours is TBA. Do not say single-stock GTH stops work. A stock stop is an equity-session instruction, not an options GTH working order.
Size the stop. Do not treat it as insurance.
Dollar risk per share is |entry − stop|. Shares = dollar risk divided by that amount, then round down. Work the formula on dollar risk per share. Run the arithmetic on the risk calculator (crypto UI; treat the unit as shares, round down). There is no stock-native calculator on denntech.io. Risk Management 101 for Stocks is the course spine. A wide bid-ask spread at the trigger can also move the child market order. The stop does not collapse the spread. It releases a market order into it.
EXAMPLE: $10,000, 66 shares, stop $51.50
EXAMPLE only — not a tape print, not a recommendation, not a fill guarantee. 1% is EXAMPLE, not a required rate and not a FINRA figure. The stop in this table is the investor.gov stop: trigger, then market order.
| Input | EXAMPLE |
|---|---|
| Account | $10,000 |
| Risk % | 1% (EXAMPLE) |
| Dollar risk | $100 |
| Entry (long) | $53.00 |
| Stop trigger | $51.50 |
| Dollar risk per share | $1.50 |
| Shares (round down) | floor(100 ÷ 1.50) = 66 |
| Planned $ risk if fill = $51.50 | 66 × $1.50 = $99 |
| Notional at entry | 66 × $53.00 = $3,498 |
| Market fill through a gap to $50.80 | 66 × ($53.00 − $50.80) = $145.20 if filled there — over the $100 budget |
| Broker stop-limit ticket (not the definition) | Different ticket. Fill TODO:VERIFY with the firm. May not fill through the gap. |
The $145.20 row is the point: a stop that has become a market order is not a fill guarantee at the stop price. Do not round up to 67 shares. 67 × $1.50 = $100.50, already over the $100 EXAMPLE budget even if the stop fills at $51.50. If floor(dollar risk ÷ risk per share) is 0, you skip. You do not widen the budget.
What this page is not
Not a fill guarantee through a gap, a halt resume, or a thin Early/Late book. Not a claim that investor.gov defines a stop-limit fill. Not Cboe C1 single-stock options GTH as live (equity-options GTH is TBA). Not overnight as live (December 6, 2026 planned). Not a live scanner.
FAQ
What is a stop-loss order?
On investor.gov the page is titled Stop Order. It is an order to buy or sell a stock once the stop price is reached. When that price is reached, the stop becomes a market order. The trigger is not a fill.
Can the fill differ from the stop price?
Yes. Investor.gov: the price at which your trade is executed may differ from the stop price, especially in a fast-moving market. A short-term fluctuation can also activate the stop.
Is a stop-limit the same as a stop order?
No. A stop-limit is a different broker ticket type. This page does not treat it as the investor.gov definition and does not invent its fill. TODO:VERIFY that ticket with your firm.
Can I use a stop in Cboe GTH for single-stock options?
Do not say single-stock GTH stops work. Cboe C1 equity-options Global Trading Hours is TBA. Index-options GTH on named products is a different clock. A stock stop is not an options GTH working order.
How do I size shares to a stop?
Shares = floor(dollar risk ÷ |entry − stop|). EXAMPLE: $10,000, 1%, $53.00 / $51.50 → 66 shares, round down. Use the risk calculator; treat the unit as shares. 1% is EXAMPLE only.
Educational only. Not financial, tax, or legal advice. Not a recommendation to buy or sell any security. Order handling is broker- and venue-dependent. Session clocks can change. Trading stocks can result in loss of capital, including loss of principal. Stops are not a fill guarantee through a gap. Definition follows investor.gov Stop Order.