TL;DRAn order that sits dormant until a specified trigger price is reached, then converts to a market order and fills immediately. Stop orders are the primary tool for both stop losses and breakout entries.
A stop order is an instruction that says: when price reaches this level, execute a market order. The order does nothing until the trigger price is touched. Once triggered, it becomes a market order and fills at the best available price.
Buy stop orders are placed above the current market price. Sell stop orders are placed below. This is the opposite of limit orders, which is a common source of confusion for beginners.
The most common use of a stop order is as a stop loss to limit risk on an open position. If you're long ES from 5,200, you might place a sell stop at 5,190 to cap your loss at 10 points ($500).
When ES trades down to 5,190, your sell stop triggers and becomes a market order. In normal conditions, you'll be filled at or very near 5,190. In fast-moving markets, slippage can result in a fill below 5,190.
The key benefit is that stop losses work automatically. You don't need to be watching the screen.
Stop orders are also used to enter trades on breakouts. If ES is consolidating between 5,190 and 5,210 and you want to buy if it breaks above 5,210, you place a buy stop at 5,210.50 (slightly above the level to confirm the break).
When price reaches 5,210.50, your buy stop triggers and you enter the trade. This technique ensures you only enter when the market confirms your thesis.
The biggest risk with stop orders is slippage. Because a triggered stop becomes a market order, you're at the mercy of whatever price is available when it fires. During news events, flash crashes, or gap openings, the fill can be significantly worse than the stop price.
Stop hunting is a real phenomenon where price briefly dips below an obvious stop level, triggers a wave of sell stops, and then reverses higher. This is why placing stops at exact round numbers or obvious chart levels is risky. Experienced traders offset their stops slightly beyond these obvious levels.
Stop loss on a long position
You buy 1 ES at 5,200 and place a sell stop at 5,190 to limit your loss to 10 points ($500).
If ES drops to 5,190, your stop triggers and becomes a sell market order. In normal market conditions, you'll be filled at 5,190 or 5,189.75 (one tick of slippage). Your loss is capped at roughly $500-$512.50.
Breakout entry with a buy stop
NQ is consolidating below resistance at 18,400. You place a buy stop at 18,405 with a sell stop (stop loss) at 18,380.
If NQ breaks above 18,400, your buy stop triggers at 18,405 and you enter long. Your risk is 25 points ($500 on NQ). If the breakout fails and NQ falls back to 18,380, your stop loss exits the position automatically.
Placing stop losses at exact round numbers or obvious chart levels
Everyone sees the same levels. Place your stop a few ticks beyond the obvious level to avoid getting stopped out by a brief wick before the real move.
Not having a stop loss because you're watching the screen
Manual exits are slower than you think, especially under stress. Always have a hard stop in the market.
Using a stop order when a stop-limit would be better (or vice versa)
Use stop (market) orders for stop losses where getting out matters most. Use stop-limit orders for entries where you want price control and missing the trade is acceptable.