The debit spread

Buy an option, sell a cheaper one further out, and pay the difference.
The only structure on this shelf where time is working against you.

What it is

Two legs, one expiry.
You buy the nearer option. That is the position and the cost.
You sell one further out. That pays for part of it, and caps what you can make.
You pay the difference on the day you open. That payment is the most you can lose.

What you are actually agreeing to

You have paid for a directional opinion with a deadline on it.
The most you can lose is what you paid — known before you enter.
The most you can make is the width less what you paid.
Nothing happens unless the stock moves your way. Sitting still is a slow loss.

The trade, written out

Everything above is the idea. This is the position — the lines you would actually send to a broker.

Order ticket

Leg	Action	Qty	Expiry	DTE	Strike	Delta	Price
1	Buy to open	+1	16 Oct 26	45	100 Call	+0.54 (54Δ)	$3.74
2	Sell to open	-1	16 Oct 26	45	105 Call	-0.32 (32Δ)	$1.77
Net	Debit	1 position	16 Oct 26	45	$5 wide	+0.22	$1.97

BUY +1 VERTICAL XYZ 16 OCT 26 100/105 CALL @ 1.97 DEBIT

Reading it back

Buy the 100 call — at the money, so it is all time value.
Sell the 105 call — it pays for part of the first one.
The net is a debit, and the ticket shows it.
That debit is your maximum loss, which is the one genuinely reassuring thing about this structure.

The argument

Bull

makes the claim

I know exactly what this costs me on the day I put it on, and the number is small. I am not selling anyone insurance, I am not short gamma, and no gap can hurt me more than the ticket price.

Bear

doubts it

You have bought a decaying asset and sold a bit of the decay back. Every quiet day costs you money. You need the move, you need it in the right direction, and you need it before the date — three things, all of which have to go right.

Ferret

settles it

The credit structures on this shelf win often and lose big. This one loses often and wins moderately. Those are not comparable on win rate, and anyone comparing them on win rate has already got the answer wrong. Give me expectancy and I will tell you which is better.

The shape of it

The debit spread on XYZ at $100 · 25% volatility · 4% rate · 45 days. Priced from the model, not written by hand.

	At expiry
Debit paid	$197
Maximum profit	$303
Maximum loss	$-197
Breakeven	$101.97

Flat and negative on the left, rising to a cap on the right. The mirror of a credit spread.
Maximum loss is the debit paid, and it is reached by doing nothing.
Maximum profit is the width less the debit.
The faint lines sit below the expiry line across most of the range — that gap is the time value you still have to lose.

Where you actually enter

The chart above is the shape at expiry. It puts the bend right next to the money, which makes the trade look like it is already on the edge. It is not — here is the day you open it.

The same structure set up at 50Δ · 45 days · credit $176. The shaded band is the room between the stock and the strike you sold.

The same price, two different days

	On day one	At expiry
Stock at $106 (the strike you sold)	$128	$324
Stock unchanged at $100	$0	$-176

You enter at the dot, already down by the cost of the spread on any honest mark.
The day-one line is well below the expiry line in the region that matters, which is the opposite of a credit trade.
Time is the enemy here. The position gets worse if nothing happens, and it does so every day.
Which is why the exit on a debit spread is usually a price, not a date.

Different ways to set it up

The same two dials, working in reverse. A debit spread bought closer to the money costs more and needs less to happen.

Same delta, four tenors

Days	Short strike	Away from spot	Credit	Max loss	Risk : reward
7	105	-5.0%	$129	$-129	—
21	105	-5.0%	$174	$-174	—
45	106	-6.0%	$176	$-176	—
90	107	-7.0%	$183	$-183	—

A short-dated debit spread is cheap and usually worthless. There is no time for the move to arrive.
A long-dated one costs more and gives the thesis room.
The panels show the gap between day one and expiry — on this structure that gap is what you are paying for, not what you are collecting.

Same tenor, three deltas

Delta	Short strike	Away from spot	Credit	Max loss	Risk : reward
40Δ	104	-4.0%	$218	$-218	—
25Δ	100	+0.0%	$307	$-307	—
15Δ	97	+3.0%	$369	$-369	—

Closer to the money costs more and is likelier to pay.
Further out is cheap for a reason.
Cheap debit spreads are the most common way retail accounts bleed — a low ticket price feels like low risk, and it is not, because the loss rate is so much higher.

A defined maximum loss you reach by doing nothing is still a loss you reach by doing nothing.

What the Greeks are doing

Four questions about the same position, and a fifth that barely applies here.
Every structure answers them differently, which is why this site never writes a general page about the Greeks.

Days left	Delta	Gamma	Theta / day	Vega	Rho
45	+21.6	+0.43	$-0.58	$+1.31	$+2.41
21	+29.9	+1.60	$-1.68	$+2.30	$+1.62
7	+43.0	+7.00	$-6.45	$+3.36	$+0.80

The position at entry — stock $100 · 25% volatility. Per contract, from the model.

Delta — which way you need the stock to go

Positive on a call debit spread — you need it up.
It is a directional trade wearing a spread’s clothes.

Theta — what time does to you

Negative. The only structure on this shelf where it is.
Every day that passes costs you, and the table above says how much.

Vega — what a change in fear does to you

Long volatility, mildly. A jump in implied volatility helps you here.
The short leg takes back part of that, which is what makes it a spread rather than a bought option.

Gamma — how fast your delta turns against you

Positive. Movement helps rather than hurts.
That is the trade you have made: you pay theta to own gamma.

Rho — what a change in interest rates does to you

Small at this tenor.
One row, as always.

Theta and gamma are one thing

This is the part that decides whether the strategy works, and it is almost never put plainly.

You cannot be paid theta without being short gamma. They are not two features of the trade. They are the rent and the risk on one lease.

The same position, three points in its life

Nothing about the position changes.
The stock sits still at $100 throughout.
Only the days left move.

Days left	Delta	Gamma	Theta / day	Vega	Rho
45	+21.6	+0.43	$-0.58	$+1.31	$+2.41
21	+29.9	+1.60	$-1.68	$+2.30	$+1.62
7	+43.0	+7.00	$-6.45	$+3.36	$+0.80

Now move the stock to $104.50

Same three dates, same spread.
Now with the stock at the strike you bought — where a debit spread is decided.

Days left	Delta	Gamma	Theta / day	Vega	Rho
45	+20.8	-0.72	$+0.46	$-2.41	$+2.32
21	+29.3	-1.75	$+1.34	$-2.75	$+1.58
7	+44.4	-6.30	$+5.42	$-3.30	$+0.82

Gamma goes from -0.72 to -6.30.
Theta goes from $+0.46 a day to $+5.42.
Both climb, and neither is available without the other.
Delta now moves roughly 9 times as far for every dollar the stock travels.

Which is what DTE actually sets

Read this section backwards from every other page on the shelf.
You are paying theta and owning gamma, not the other way round.
Shorten the tenor and the daily cost rises with the sensitivity — the same lease, taken from the other side.

The trap

The trap on a debit spread is how comfortable the defined risk feels.

The most you can lose is the price of the ticket. You reach it by doing nothing at all.

A credit spread makes money when nothing happens.
A debit spread loses the whole ticket when nothing happens.
Nothing happening is the single most likely outcome for any stock over a few weeks.
So the structure that feels safest is the one whose most likely outcome is a total loss of what you put in.

Why it matters

It changes what a good win rate looks like. A debit spread strategy can be sound at a 35% win rate and a credit spread strategy unsound at 85%.
The two cannot be compared on the same scale, and almost every published comparison does exactly that.

How this shows up in our tests — pending. No result has been published on this structure yet.