Home › Guides › Options: strategies & spreads

Diagonal spread explained, outcome by outcome

A diagonal spread buys a later option at one strike and sells a nearer one at another. It is a calendar that has been tilted, so it makes money from time and from a slow drift in one direction.

Options guide · 9-minute read · Updated 2026-10-29

What a diagonal spread is

Two options on the same stock. Different strikes and different expiry dates. That is the whole definition.

The version almost everyone means:

• Buy a later option, closer to the money.
• Sell a nearer option, further out of the money.

The one you buy has more time and a better strike, so it always costs more than the one you sell. A long diagonal is always a Net debit, and that debit is the most you can lose.

Why bother? Because you get two engines instead of one. The nearer option you sold drains its time value fast, which pays you for waiting. And because the strikes are different, you also get paid if the stock drifts your way. A plain calendar gives you only the first of those.

The full map of what else lives out here is in option strategies beyond the wheel.

Where it sits between a calendar and a vertical

Three spreads, three combinations of the same two dials.

So a diagonal is the middle setting. Narrow the strikes until they match and you have a calendar spread. Pull the expiries together until they match and you have a vertical spread.

That middle setting is why it suits a view most strategies cannot express: mildly bullish, over weeks, without wanting to pay for 100 shares.

A worked example (an illustration, not a trade idea)

Granite Peak Tools, a made-up company, trades at $50. You think it grinds higher over the next couple of months. Nothing dramatic.

• Buy the 90-day $50 call for $3.50 → pay $350
• Sell the 30-day $55 call for $0.50 → collect $50
• Net debit: $300. That is the most you can lose.

Compare that with buying 100 shares at $50, which costs $5,000 and risks all of it.

Thirty days pass and the stock drifts to $54. Now:

• The $55 call you sold expires worthless. You keep the $50 — it is already in the debit above.
• The $50 call you own has 60 days left and the stock is $4 above the strike. It is worth $535.
• Result: $535 − $300 = +$235.

You can now sell another call against the long leg and start the cycle again, which is where the comparison with the wheel strategy comes in: same rhythm of selling a call every month, a fifteenth of the cash tied up, and no shares and no dividends.

Every outcome at the short expiry

Same trade, same $300 debit. The long $50 call always has 60 days left when the short one expires.

Three things are worth staring at.

The best outcome is the stock finishing right at the short strike. At $55 the call you sold dies worthless and the call you own still carries real value plus two months of time. That is the sweet spot of every diagonal.

Above the short strike the gain flattens out. At $60 and $70 the short call is costing you dollar for dollar what the long call is gaining. The trade stops caring about the rally. This is Capped upside, same as a covered call.

A flat stock is a small loss here, not a win. The $50 row loses $15. The long call lost $65 of time value over those 30 days and the short call only brought in $50. A diagonal needs some drift. A calendar does not — it needs the opposite.

The one rule that keeps a rally from hurting you

There is a hard check to run before you open any diagonal, and it is arithmetic, not judgement.

Your net debit must be smaller than the gap between the two strikes.

In the example: the gap is $55 − $50 = $5, which is $500 per contract. The debit was $300. So $300 < $500, and the rule passes.

Why it matters: if the stock rockets and your short call is assigned, the worst you can do is buy at $50 through your long call and deliver at $55. That is the $500 gap, minus the $300 you paid, which is +$200. A rally cannot turn into a loss.

Flip it. Pay a $600 debit on the same $500 gap and a big rally locks in −$100 no matter what. You would have built a trade that loses when you are right.

The poor man's covered call is a diagonal

A Poor man's covered call is this same structure with the dials turned to one extreme: the long leg is a deep in-the-money LEAPS call, a year or more out, standing in for 100 shares, and you sell a short-dated call against it month after month.

Everything on this page still applies to it, the strike-gap rule included. What changes is that a deep long leg moves more like the stock, so the position is more directional and less about time.

What it needs from you and your broker

Two legs with two different expiries sits above covered calls on most brokers' Options approval level ladder, and usually needs a margin account. Many Canadian brokers do not allow multi-leg spreads inside a TFSA or RRSP at all, so check your broker's current options agreement before building a plan around one.

Before you open one, write down the debit, the strike gap, and the price where the whole debit is gone. The options payoff calculator gives you all three in a minute.

Questions