A stock clears your target and keeps climbing. At 40% above the planned sale price, the old target no longer tells you what to do with the open position.
Selling everything ends your exposure. Holding everything keeps all the upside and all the give-back risk. A written partial-exit and trailing rule gives you a third choice: realise some profit and let the remaining shares respond to price.
Define parabolic before you own one
"It looks vertical" is not an exit rule. Define the condition in terms your journal can check. Examples include:
- price closes a set percentage above a moving average;
- the current range exceeds a multiple of recent ATR;
- price reaches a chosen multiple of initial risk; or
- the stock rises a specified percentage above the original target within a short period.
These are hypothetical rule types, not universal settings. Test one against your own holding period and market. The definition must exist before excitement changes it.
Use a partial exit and a trailing rule together
The partial exit converts some open profit into realised profit. The trailing rule gives the remainder a conditional exit as price rises.
Write down four details:
- What condition triggers the first sale?
- What fraction will you sell?
- Where will the initial trail sit?
- How and when will the trail move?
Avoid a trail that you widen after price falls. That turns a predefined exit into a new decision made under pressure.
Worked example with practical rules
Consider a hypothetical 100-share position bought at $40 with an initial stop at $36. Initial risk is $4 per share, so one R equals $400.
The original target is $52. Price reaches it, then closes at $58. The trader's written parabolic rule triggers when price closes more than 10% above the target.
- Sell 50 shares at the next available price, assumed here to be $58.
- Trail the remaining 50 shares below the prior two-day low.
- Raise the trail only after a new daily close creates a higher two-day low.
- Do not add new shares while the parabolic rule is active.
The first sale realises $900 before costs: 50 x ($58 - $40). Suppose the trailing level later rises to $55. The stock gaps down and the remaining shares fill at $52, not $55. That second parcel realises $600: 50 x ($52 - $40). Total realised profit is $1,500, or 3.75R before costs.
The example does not prove those percentages are optimal. It shows how to make the decisions auditable and how a gap changes the result.
A trailing stop does not lock in its trigger price
A stop is an instruction that activates an order. If a fast reversal crosses the trigger, the fill can be lower. An overnight gap can open below the entire trailing range.
Liquidity also matters. A thin stock may show a quoted price without enough buyers for your full order. Slippage can increase with position size, volatility and the speed of the reversal. Treat the trailing level as a decision point, not a guaranteed sale price.
This is why the partial exit has a job. It reduces the number of shares exposed to a poor fill while leaving a smaller parcel in the move.
Choose the trail that matches the trade
A tight percentage trail responds quickly but can exit during an ordinary pullback. A wider ATR trail gives price more room but returns more open profit. A prior-low rule follows visible structure but can sit far away after a steep run.
Compare methods on completed trades. Record the actual partial fill, stop trigger, final fill and highest price reached after entry. Then compare the realised outcome with the original fixed target. One dramatic winner cannot tell you which rule fits your strategy.
The position's original size also shapes the choice. Review position sizing in volatile markets before treating the exit rule as a substitute for entry risk.
Frequently asked questions
What percentage should I sell when a stock goes parabolic?
There is no universal fraction. Choose a repeatable percentage that reduces exposure while leaving a meaningful remainder, then test it on your own completed trades.
How tight should a trailing stop be?
Match it to the strategy's timeframe and the stock's recent movement. A trail inside normal daily noise can close the trade before the trend changes.
Can a trailing stop fill below its stop price?
Yes. Gaps, fast markets and limited liquidity can produce a lower fill than the trigger price.
Should I move my target higher after every strong day?
Use the rule you wrote before the move. Repeatedly raising a target without a trailing or partial-exit rule leaves no defined point for realising profit.
Start the 30-day trial to record partial fills and the final trailing exit for your next fast winner in Swingfolio.
General information only. Not financial advice. Trading involves significant risk of loss. Past performance is not indicative of future results. Always do your own research and consider seeking advice from a licensed financial advisor.