Debit Spreads
ES: Spreads de Débito PT: Spreads de Débito
Structures paid for upfront to bet on direction with defined risk: when they pay off, how right you have to be, and why time works against you.
What a debit spread is
A debit spread is any structure in which the premium paid for the long legs exceeds the premium collected on the short legs, so money leaves your account at entry. The two canonical cases are the bull call spread — buy the lower-strike call, sell the higher one — and the bear put spread — buy the higher-strike put, sell the lower one. In both, the purchased option expresses the directional thesis and the sold one cheapens entry in exchange for giving up upside beyond its strike. The debit paid is, from the first second, your maximum possible loss: no scenario can cost you more.
The mathematics of the trade
The whole structure is determined by two numbers: strike width and debit. Maximum gain is width minus debit, achieved if the underlying finishes beyond the sold strike. Maximum loss is the debit, realised if it finishes below the purchased strike in a bull call spread. The breakeven is the purchased strike plus the debit in a bullish structure, or the purchased strike minus the debit in a bearish one. A concrete example: with the stock at 100, you buy the 100 call for 4.20 and sell the 110 for 1.70, paying a 2.50 debit on a 10-wide spread. Risk $250, maximum gain $750, breakeven 102.50. The risk-reward is 1-to-3, but collecting it in full requires the stock to rise 10%.
Time works against you
A debit spread carries negative theta: every day that passes without the underlying moving subtracts value from the position. This is the opposite of credit structures and has a practical consequence that is consistently underestimated: being right about direction is not enough, you have to be right on schedule. An 8% move that arrives the week after expiration is identical, in outcome, to never having been right at all. Negative theta is also larger the closer to the money the purchased leg sits, so the structures that look most attractive on probability are the ones that bleed most when the market stands still. The offset is that the spread is also vega positive: if implied volatility expands, the position gains even if price does not move.
When it makes sense and when it does not
A debit spread pays off when three conditions hold at once. First, low IV Rank — below 25–30 — because you are buying premium and want it cheap; buying debit with inflated volatility is the recipe for the classic "I was right and lost" after IV collapses. Second, a thesis with a calendar: it is not enough to believe it will rise, you need a reason for it to rise before a date. Third, an identifiable catalyst or an established trend that gives that calendar meaning. Conversely it makes no sense when volatility is expensive, when the thesis has an open-ended horizon — a credit structure or simply stock is better there — or when the move required to reach breakeven exceeds the expected move the market itself is pricing.
Management: when to exit
Managing debits is less automatic than managing credits because the profit accrues at the end. Three common guidelines. First, take profits around 50–75% of maximum gain rather than waiting for expiration: the final stretch requires the underlying to sit still above the sold strike for days, and that time carries an opportunity cost and reversal risk. Second, set a management stop — many use 50% of the debit — rather than letting it run to zero: even with capped loss, recovering capital before it reaches zero improves compounding. Third, monitor breakeven against the expected move: if halfway through the life the underlying needs more than one standard deviation to reach it in the time remaining, the trade no longer has the probability you entered with.