Calendars & diagonals
Trade time itself: sell near, buy far
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Every spread so far ran across price. This one runs sideways through time — sell the near date, buy the far one, and pocket the difference in decay.
Welcome to the summit. Every spread you’ve built so far used two different strikes at the same expiry — a bet spread across price. A calendar spread flips that idea on its side: same strike, two different expiries. It’s a spread across time.
You sell a short-dated option and buy a longer-dated one at the same strike. The whole trade lives on a quiet truth about options: near-term contracts lose their time value faster than far-term ones. You’re here to harvest that gap.
That’s the entire defining feature: one shared strike, one near expiry you sell, one far expiry you buy. Different strikes make it a vertical; different dates make it a calendar.
Fast decay versus slow decay
Time decay isn’t linear. An option with a week left melts far faster than one with three months left — the closer expiry gets, the more violently that time value drains away. A calendar puts that imbalance to work.
You sell the fast-melting near option and buy the slow-melting far one. Ideally the near leg you sold decays to almost nothing while the far leg you own hangs on to most of its value. You pocket the difference between fast and slow.
You’re not betting on price. You’re pocketing the difference between fast time decay and slow time decay.
The sweet spot: calm near the strike
A calendar wants the stock to hover close to the shared strike as the near option expires. That keeps the sold leg decaying beautifully while your longer leg holds its value. Calm, near the strike, is the calendar’s happy place.
The tent-shaped payoff below tells the story at a glance: profit peaks right at the strike and slopes away on either side. There’s even a bonus — a rise in volatility tends to lift your longer-dated leg more than the near one, adding a little tailwind.
A wild, fast move in either direction hurts a calendar. Push the stock far from the strike and both legs shift together, the sweet spot vanishes, and your carefully built time-edge evaporates. This is a trade for quiet, not chaos.
The diagonal: tilt the calendar
A diagonal spread is a calendar with a twist: the two options use different strikes and different expiries. It blends the time-decay edge of a calendar with the directional lean of a vertical — a calendar leaning gently in the direction you favour.
Traders reach for diagonals when they want to earn from decay while still betting the stock drifts softly one way. It’s the most flexible shape on the mountain, borrowing a little from every spread you’ve learned.
Vertical = same date, different strikes. Calendar = same strike, different dates. Diagonal = different strikes AND different dates. Once you see the pattern, every advanced strategy is just a remix of these three.
You’ve reached the summit
Look how far you’ve climbed. You started with a single pair of legs and a capped bet. Now you can build income machines, defined-risk ranges, volatility plays, and spreads that trade time itself. Every peak up here was assembled from the same handful of ideas.
Same strike, two dates: sell the fast-decaying near option, own the slow far one, and root for calm. You’ve climbed every peak on the mountain. 🏔️🎓