Lesson 15 of 20 · 7 min
Spreads as a structure, not a strategy
Combining options changes the shape of the payoff; the shape is a fact, the choice is not this curriculum's business.
When two or more options on the same underlying are held together, the combined position has a payoff shape that is simply the sum of the individual ones. That summation is arithmetic, and understanding it means you can read any structure you encounter rather than memorising names.
The general mechanism: each option contributes a kink at its strike and a slope beyond it. Long positions contribute upward slope in their favourable direction; short positions contribute downward slope. Adding a short option at a further strike truncates the slope that a long option would otherwise continue, which is what turns an unbounded shape into a bounded one.
Reading any multi-leg structure comes down to four questions:
- How many strikes are involved? That is how many kinks the diagram has.
- Is the net premium paid or received? That sets the vertical position of the whole shape.
- Is either end of the shape unbounded? Check whether the outermost leg is long or short.
- Where does the shape cross zero? Those are the breakevens.
Two properties of spreads are worth stating plainly because they are frequently oversold. The bounded shape is bought by giving up the unbounded part — there is no configuration that keeps the tail and removes the risk. And each additional leg is another spread crossed and another contract that must be closed, so a structure that looks efficient on a diagram can be materially less so after transaction costs, particularly in thinly traded strikes.
This lesson describes how shapes combine. It does not suggest constructing any of them.
Key terms
- Spread (structure)
- A position combining two or more options on the same underlying, whose payoff is the sum of the legs.
- Leg
- One option within a multi-option position. Each leg has its own strike, premium and spread cost.
- Net debit and net credit
- Whether the combination costs premium overall or collects it. It sets where the whole payoff shape sits vertically.
Worked example
Summing two legs into one shape
Long one $50 call at $2.00, short one $55 call at $0.80. Same expiry.
- Net premium
- $1.20 paid
- Kinks
- Two — at $50 and $55
- Below $50
- −$120
- Breakeven
- $51.20
- At and above $55
- +$380
- At $80
- +$380
$120 per contract.
Both legs lapse.
Lower strike plus net premium.
($55 − $50 − $1.20) × 100, and no more.
Unchanged — the short leg truncated the slope.
The short leg cut the premium by $80 and capped the outcome at $380. That is the entire trade being made, stated in two numbers.
Check yourself
You hold a long $50 call and a short $55 call for a net $1.20. What happens to the position's value if the underlying finishes at $80 rather than $55?
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Educational only. Nothing in this lesson is investment, legal or tax advice, or a recommendation to enter into any transaction. Figures are illustrative and computed from the inputs stated in the lesson.