Diagonal Spread
A diagonal spread combines a calendar and a vertical, using different strikes and different expirations. Learn how it blends time decay with a directional lean.
A diagonal spread sells one option and buys another at a different strike and a different expiration. It is a hybrid: part calendar spread, part vertical spread, blending time decay with a directional lean.
The name comes from the option grid. A vertical moves down a column of strikes, a calendar moves across a row of dates, and a diagonal cuts across both at once. Let me show you what that buys you.
Time Decay Plus a Direction
A plain calendar spread uses the same strike on both legs, so it is purely a bet on time and stillness. A diagonal tilts that bet by moving the two legs to different strikes, which adds a directional opinion on top of the time-decay engine.
You still sell a near-term option to harvest fast decay and buy a longer-term option to hold value. But by choosing different strikes, you lean the position bullish or bearish. It is a calendar that also wants the stock to drift a certain way, giving you two ways to profit instead of one.
Watch It Work
Apple is at $200 and you are mildly bullish, expecting a slow drift upward over the next couple of months. You build a bullish call diagonal:
- Sell the 30-day $210 call for $3 a share
- Buy the 90-day $200 call for $8 a share
- Net cost: $5 a share, or $500
Apple drifts up toward $210 as the near-term expires. The $210 call you sold decays and expires near worthless, so you keep that $3. Your longer-dated $200 call has gained value from the move up. You profit from both the decay and the drift, and you can sell another near-term call to keep the income going.
Apple stalls or falls. The short call still decays in your favor, cushioning the trade, but your long call loses value. A diagonal softens a wrong direction better than a plain vertical, because the sold option keeps paying you time decay.
Why Traders Like It
A diagonal is popular because it is flexible and efficient.
It lowers cost. The premium from the short option offsets part of the cost of the long option, so you control a longer-dated position for less.
It pays you to wait. Each near-term option you sell drips income while you hold the longer-dated leg, much like a covered call does against stock.
That second idea is exactly the engine behind a poor man's covered call, which is just a deep-in-the-money call diagonal used to mimic owning shares. The diagonal's blend of income and direction makes it one of the more versatile two-leg structures.
- A diagonal spread uses different strikes and different expirations.
- It blends a calendar's time decay with a vertical's directional lean.
- The short option's premium lowers the cost of the long option.
- It pays you income while you wait for the drift.
Pop Quiz
Three quick questions to see what stuck. Pick an answer and the explanation shows up right away.
What makes a spread "diagonal"?
A diagonal cuts across both strike and expiration, unlike a vertical (one date) or calendar (one strike).
What two engines does a diagonal combine?
It blends the calendar's time decay with the vertical's directional tilt, giving two ways to profit.
Which well-known trade is essentially a deep-in-the-money call diagonal?
A poor man's covered call is a call diagonal that uses a deep ITM long call in place of 100 shares.
Bottom Line
A diagonal spread is a calendar with an opinion. By choosing different strikes as well as different dates, you keep the time-decay engine of a calendar and bolt on the directional lean of a vertical. You harvest decay while betting on a gentle drift.
That combination makes it flexible and cost-efficient: the short leg funds part of the long leg and pays you to wait. It is the backbone of trades like the poor man's covered call, and a favorite for expressing a patient, mildly directional view.
Keep going: the same-strike version is the calendar spread, the same-date version is the vertical spread, and the popular application is the poor man's covered call.