What it means
Complex trades, such as spreads, straddles and arbitrage positions, are built from several legs designed to work together. If a trader closes only some of those legs, the position that remains is no longer the balanced strategy that was planned.
The leftover leg might carry the full risk of the market with nothing to offset it. Traders have reasons for legging out.
They might close the profitable leg to bank a gain and let the other leg run, or they may find it hard to close all the legs together at fair prices in a thinly traded market. Some do it deliberately to express a new view on market direction, accepting the extra risk.
The danger is timing risk. Between closing the first leg and the second, prices can move sharply against the position, turning a controlled strategy into a large loss.
In fast markets, the gap can be a matter of seconds, which is why professionals often prefer to trade all the legs as a single order, known as a package or spread order. Risk managers and finance teams watch for legging out because it changes the risk profile of a portfolio, sometimes without anyone formally approving the change.
Trading limits usually say whether a trader may close single legs, and whether the remaining exposure must be reported. A partly closed position may also face different margin requirements.
A related nuance is that legging out is not always a mistake. In an arbitrage trade, a trader may leg out when one side has moved far enough in their favour and the other side is stuck.
What matters is that the decision is deliberate, the new exposure is understood and the limits allow it.
In practice
Real-world examples.
Example
A trader holds a calendar spread and sells the near-dated option early to take a quick profit. The longer-dated option is left open and loses value as the market goes quiet. The overall result is worse than closing both together.
Example
An arbitrage desk has bought a share on one exchange and sold it on another. One exchange becomes illiquid, so the desk closes the liquid leg first. The remaining leg is exposed to price moves until it can be closed.
Example
A corporate treasurer holds a currency swap as part of a hedge and decides to close only one leg when the forecast cash flow disappears. The remaining leg is now an unhedged exposure. The treasurer has to explain the new risk to the audit committee.
Formula
Calculation
Net profit or loss = sum of profit or loss on each leg, where profit or loss on a leg = (exit price - entry price) for a bought leg, or (entry price - exit price) for a sold leg
A trader opens a bull call spread by buying a call with a $100 strike at $6 and selling a call with a $110 strike at $2.50, a net cost of $3.50 per share. She legs out by selling the long call at $9, a gain of $9 - $6 = $3 per share. The short call is left open, the share price rises to $118, and she buys it back at $8.50, a loss of $8.50 - $2.50 = $6 per share. The total is $3 - $6 = -$3 per share, a loss of $300 on a 100-share contract, whereas holding the whole spread above $110 would have earned $10 - $3.50 = $6.50 per share, or $650.Case study
Seen in the real world.
Zenith Commodity Partners is an illustrative, fictional trading firm that held a spread between two oil contracts, long one month and short another. When prices spiked, a junior trader sold the long leg to lock in a profit of $180,000, planning to close the short leg a moment later.
The market kept rising during the delay, and the short leg lost $260,000 before it could be closed, turning a combined gain into a net loss of $80,000. The risk manager reviewed the incident and changed the rules so that spreads must be closed as a single package order. The illustrative lesson is that the leg that is left open can be much riskier than the full position.
Watch out
Common mistakes.
- Closing the profitable leg and ignoring the remaining leg, which now carries the whole market risk.
- Assuming prices will stay still during the short gap between closing the legs.
- Overlooking higher margin or capital charges on the remaining leg once it stands alone.
Questions
People also ask.
What is the difference between legging in and legging out?
Legging in is building a multi-part position one leg at a time, while legging out is closing it one leg at a time.
Why do professionals prefer package orders?
A package order executes all the legs together at a net price, which removes the risk of the market moving between trades.
Is legging out always a bad idea?
No, it can be a deliberate decision, but it should be made knowingly with the new exposure measured and approved.
From the founder's library
Take it further with the book.
Build your financial confidence beyond this definition. Shihan's full-length guide, Accounting Fundamentals, takes the same plain-English approach and turns it into a complete, practical playbook for non-finance managers, business owners and students - with chapter-end quiz answers and presentation slides included.
25% off with code MMHQ25, applied at checkout. Priced in USD - checkout may show the equivalent in your local currency.
View the book and save 25%Related