Vertical Spreads Explained: Debit vs. Credit, Bull vs. Bear

Editorial responsibility: Oliver Sinz · Last verified: October 26, 2026

A vertical spread combines one long option and one short option of the same type, both calls or both puts, on the same underlying and with the same expiration, but at different strike prices. The four standard versions are the bull call spread and the bear put spread, which are opened for a net debit, and the bull put spread and the bear call spread, which are opened for a net credit. All four have a capped maximum profit and, at expiration, a capped maximum loss.

Vertical spreads are usually sorted by two labels: bullish or bearish, debit or credit. The second label matters much less than it seems. A debit spread and a credit spread with the same outlook on the same two strikes, such as a bull call spread and a bull put spread, have nearly the same payoff; they differ mainly in when the cash changes hands. What sets the chance of profit, the payoff ratio, and even whether time decay helps or hurts is where the strikes sit relative to the stock price. This guide works through all four spreads on one option chain.

All prices in this article are hypothetical, model-generated illustrations, not market quotes. Nothing here is a recommendation to trade.

How the four vertical spreads are built

In the table, W is the strike width (higher strike minus lower strike), D is the net debit paid, and C is the net credit received. Amounts are per share; a standard U.S. equity option contract covers 100 shares.

These formulas match the Options Industry Council’s pages for the bull call spread, bear put spread, bull put spread, and bear call spread. Two rules decode the whole table:

• Direction comes from which strike you buy. Buying the lower strike is bullish and buying the higher strike is bearish, whether the options are calls or puts.
• Debit or credit comes from the option type. A lower-strike call is worth more than a higher-strike call, so a bull call spread costs money. A higher-strike put is worth more than a lower-strike put, so a bull put spread brings money in.

The same positions go by other names. A bull call spread is also a call debit spread or long call vertical; a bear put spread is a put debit spread; a bull put spread is a put credit spread or short put vertical; a bear call spread is a call credit spread. In bond markets, “credit spread” means something unrelated: the yield gap between a riskier bond and a Treasury.

A worked example: four spreads on one option chain

Hypothetical assumptions:

• Stock XYZ at $100.00, 45 calendar days to expiration
• 25% implied volatility at every strike, 4.0% risk-free rate, no dividends
• Premiums are Black–Scholes–Merton theoretical values (Black and Scholes, 1973; Merton, 1973), rounded to the cent and treated as frictionless fills, with no bid-ask spread or commissions

The model prices European-style options. Because XYZ pays no dividend, early exercise of an American-style call is never optimal, so its value is the same (Merton, 1973). For the puts, a 2,000-step binomial tree puts the extra value of American-style exercise at about 1 cent or less for the 90 and 95 puts and about 3.5 cents for the 100 put.

The four spreads below use common placements: the debit spreads buy the at-the-money option, and the credit spreads sell an option $5 out of the money.

The probabilities are risk-neutral: they come from the same lognormal assumptions that produced the prices and are not forecasts of what XYZ will actually do. Expiration P&L per contract:

Plotted, each spread is a flat floor, a sloped section between the strikes, and a flat ceiling. The at-the-money debit spreads risk about $2 to make about $3 and finish profitable roughly 41% of the time under the model. The out-of-the-money credit spreads risk about $4 to make about $1 and finish profitable roughly 75% of the time. That contrast is usually credited to “debit versus credit.” The next two sections show that it comes from strike placement.

Credit spread vs. debit spread: same payoff, different cash flow

A bull call spread plus a bear put spread on the same two strikes pays exactly the strike width at expiration wherever the stock finishes. That combination is a box spread, so for European-style options its fair value is the present value of the width. Because the bull put spread is the other side of the bear put spread:

Bull call spread debit + bull put spread credit = PV(width), when both use the same strikes and expiration.

This follows from put-call parity (Stoll, 1969). The stock and any dividends drop out because they appear identically at both strikes. In the example, PV($5) = $4.975 for 45 days at 4%. The 100/105 call spread costs $1.97 and the 100/105 put spread brings in $3.01, which sum to $4.98 after rounding.

The two-cent gap (2.5 cents before rounding) is interest: $5 minus its present value is about 2.5 cents for 45 days at 4%. The debit buyer gives up interest on the $1.97 paid, and the credit seller can earn interest on the $3.01 received. Together those two amounts equal the gap, so after financing the positions are the same. The OIC strategy pages make the same point: the payoff profiles are the same once adjusted for the net cost to carry, and the chief difference is the timing of the cash flows (the bull put page adds the potential for early assignment).

The same identity applies to the “high-probability” credit spread above. The bull put 95/90 that collects $0.94 is economically the bull call 90/95 spread, bought for $4.05 with two in-the-money calls: risk $4.05 to make $0.95, breakeven $94.05.

The equivalence rests on three assumptions:

• European exercise. With American-style options it is only approximate. The binomial tree adds about 8.7 cents of early-exercise value to the in-the-money 105 put and 3.5 cents to the 100 put, so an American 100/105 put spread is worth about $3.06 instead of $3.01. The extra credit pays the seller for granting the right to exercise early.
• One interest rate. The rate embedded in option prices need not equal Treasury yields. van Binsbergen, Diamond, and Grotteria (2022) estimate that rates implied by index-option box spreads run roughly 0.4 percentage points above Treasury yields on average.
• Comparable fills. In-the-money and out-of-the-money legs can trade with different bid-ask spreads. The cheaper version to execute is the one with the better actual quotes, not the better label.

Strike placement sets probability, payoff, and time decay

The table holds the width at $5 and slides a bullish vertical from deep in the money to far out of the money. The first two price columns show both ways to build each position; the rest describe the call version. Put credits are European model values; with American-style puts, the credits would be higher by amounts ranging from under 1 cent (85/90) to about 15 cents (110/115).

1. Probability and payoff trade off. Moving the strikes below the stock price raises the chance of profit and shrinks the payoff relative to the risk; moving them above does the reverse.
2. No row is a bargain under the model. Each price is the present value of the spread’s expected payoff under the model’s risk-neutral probabilities. For the 100/105 spread, the expected payoff at expiration is $1.98, which discounts to $1.97.
3. Theta and vega change sign as the strikes pass the stock price. In this table, spreads centered below $100 gain from time decay and lose when implied volatility rises. Spreads centered above $100 do the opposite, whether they are built from calls or puts.

The price of a spread is a probability

The first two points come from an exact relationship. Breeden and Litzenberger (1978) showed that option prices across strikes encode the market’s risk-neutral distribution. For European options:

Call-spread debit ÷ width = the discounted risk-neutral probability that the stock finishes above each strike, averaged across the strike range.

For the 100/105 spread, $1.97 ÷ $5 = 39.4%, and the model’s chance that XYZ finishes above $102.50, the middle of the spread, is also about 39.4%. The same identity for puts gives the bull put 95/90 a credit ÷ width of $0.94 ÷ $5 ≈ 19%, close to the model’s 18% chance that XYZ finishes below $92.50. A put credit spread that collects one-third of its width is therefore priced as if there were roughly a one-in-three chance that the stock finishes below the middle of the spread. The identity uses actual spread prices, so it already reflects any volatility skew. It describes risk-neutral pricing, not real-world odds.

Spread width: how much of a single option you keep

Selling the higher-strike call gives up the upside above that strike, and with it much of the long call’s exposure to time and volatility. Cost and maximum profit are per share; delta and the Greeks are per contract.

The 100/105 spread costs 53% of the call and keeps 40% of its delta, but only 13% of its time decay and 9% of its vega. Narrow spreads behave like bets on where the stock finishes; wide spreads converge on the single option.

Before expiration: being right early pays only part of the width

Before expiration, a spread is worth its current market value, not its expiration payoff. The grid reprices the bull call 100/105 with the same model and 25% implied volatility. Each cell is the P&L per contract from closing at the unrounded model value, against the $197 debit; the 45-day row shows an immediate move.

• A fast, correct forecast is only partly rewarded. If XYZ jumps to $110 right after entry, the spread is worth $3.93, not $5.00: a $196 gain against the $303 maximum. The rest arrives only as time passes.
• Losses are muted early, too. An immediate drop to $90 costs $160, not $197.
• Near the middle of the strikes, time barely matters. At $102.50 the P&L stays near +$54 throughout. Below the middle, time works against the position; above it, time works for it.

The out-of-the-money credit spread behaves the same way. With XYZ unchanged at $100, the bull put 95/90 shows a model gain of $24 with 30 days left, $59 with 15 days left, and $90 with 5 days left, out of a $94 maximum. At $97.50, still above the short strike, it shows a $22 loss with 30 days left. Real closing trades also pay the bid-ask spread.

The Greeks follow the price, not the label

Greeks are model sensitivities: the approximate change in theoretical value for a small change in one input, with the others held constant. For the 100/105 spread with 30 days left, per contract:

Below roughly the middle of the strikes, the long option dominates: gamma and vega are positive and time decay is a cost. Above it, the short option dominates and the signs flip (here gamma and vega change sign near $101.90 and theta near $102.50). The 100/105 put spread has the same delta, gamma, and vega; its theta is lower by about 5.5 cents a day per contract, the interest accruing on the present value of the width.

So the rule that “credit spreads collect time decay and debit spreads pay it” describes the usual placement, not the label. The OIC pages describe time as helping both credit spreads and hurting both debit spreads, while noting that the two legs’ time-decay effects may largely offset. The in-the-money bull call 90/95 is a debit spread with positive theta.

Implied volatility works the same way. P&L per contract for the 100/105 spread with 30 days left, at unrounded model values, if implied volatility moves to each level at every strike:

At $95, rising implied volatility helps; at $110, it hurts. Advice to “sell credit spreads when implied volatility is high” is, in effect, advice about being short vega, and a bullish short-vega position can be built from a put credit spread or an in-the-money call debit spread alike. Whether it pays depends on the stock’s price path and on how the volatility it later realizes compares with the implied volatility paid. Real changes in implied volatility are also rarely uniform across strikes.

Early assignment and dividends

Options on individual U.S. stocks are American-style, so a short leg can be assigned on any business day, and a debit spread has a short leg too. The OIC pages note that early assignment generally occurs when a short call faces an ex-dividend date or a short put is deep in the money. Covering an assignment with the long option also means holding a stock position for one business day, because assignment notices arrive with a delay.

A short call before an ex-dividend date. Suppose that after entry XYZ declares a regular $1.00 dividend that goes ex 10 days before expiration, and XYZ trades at $112 the day before. After the expected drop to $111, the model values the 105 call at $6.29, only $0.29 of time value. Exercising the day before is worth $7.00 (the $112 stock, dividend included, minus the $105 strike), so a holder gains by exercising: a call holder who exercises before the ex-date is entitled to the dividend, and an assigned writer must deliver the shares plus the dividend (OIC).

A bull call spread owner who is assigned and does nothing starts the ex-date short 100 shares and owes the $100 dividend. The long 100 call still caps the upside, but the position is worth $4.12 per share instead of $4.83 for the intact spread: a cost of about $71 per spread, the dividend minus the short call’s remaining time value. The long 100 call has only about $0.12 of time value, so exercising it before the ex-date is also rational. If the short call is then assigned, the shares are delivered and the spread pays its full $5 width ten days early; if not, the account is left long stock against a short 105 call, with no floor below $100. Closing the spread before the ex-date avoids both outcomes.

A deep in-the-money short put. If XYZ falls to $85 with 10 days left, a European 95 put is worth $9.90, below its $10 intrinsic value, while the American version is worth exactly $10, so the holder loses nothing by exercising. A bull put 95/90 owner who is assigned buys 100 shares at $95 ($9,500), protected below $90 by the long put. The loss limit still holds if the long put is kept, but the shares need cash or margin to carry.

Most index options are European-style (OIC), which removes early assignment, and index options are traditionally cash-settled, so exercise produces a cash payment rather than shares (OIC). Options on stocks and ETFs settle in shares, so the expiration issues below apply to them.

Expiration: when the stock finishes between the strikes

The defined-risk label assumes both legs settle together. Under OCC’s exercise-by-exception procedure, expiring options at least $0.01 in the money are exercised unless contrary instructions are given, and a brokerage firm’s own threshold may differ (OIC). Holders of expiring equity options have until 5:30 p.m. ET on expiration day to make final exercise decisions, and firms may set earlier cut-offs (FINRA).

Suppose XYZ closes at $103 on expiration day. The bull call 100/105 expiration table shows +$103, but the long 100 call is $3 in the money and will be exercised by exception, while the short 105 call, $2 out of the money, is very likely to expire. The account now holds 100 shares bought at $100: $10,000 of stock for a position that cost $197. If XYZ opens the next trading day at $97, the P&L is ($97 − $100 − $1.97) × 100 = −$497, well beyond the $197 “maximum” loss. Selling the long call before the close keeps its value and avoids the stock; a do-not-exercise instruction avoids the stock but gives up the call’s $300 of intrinsic value.

A close near the short strike is harder, because the short leg is outside the owner’s control. The OIC pages note that the owner cannot know for sure until the Monday after expiration whether the short option was assigned. Because holders can decide until the 5:30 p.m. ET cut-off, an after-hours move can turn an expected expiration into an assignment, or the reverse. A wrong guess leaves an unintended stock position over the weekend.

Costs, capital, and margin

Transaction costs. Two legs mean two bid-ask spreads and two commissions to open, and again to close. Suppose each leg fills $0.05 worse than its theoretical value and the commission is $0.65 per contract (both hypothetical):

• Bull call 100/105: effective debit $2.07 plus $1.30. Max loss $208.30 instead of $197; max profit $291.70 instead of $303 (3.7% less); breakeven about $102.08.
• Bull put 95/90: effective credit $0.84 minus $1.30. Max profit $82.70 instead of $94 (12.0% less); max loss $417.30 instead of $406; breakeven about $94.17.

The same dollar friction takes a much larger share of a small credit. Because each spread is fairly priced under the model, these frictions become an expected cost of about $11 per spread before any closing trades. Entering both legs as one spread order avoids the risk of the price moving between separate fills.

Capital. Under Cboe’s strategy-based rules (Cboe Margin Manual), a debit spread’s long option must be paid for in full and the short option’s proceeds may be applied, so the requirement is the net debit. For a credit spread, the requirement is the spread’s maximum potential loss computed from the intrinsic values at each strike (or the short option’s own requirement, if lower), with the long option paid in full and the short option’s proceeds applied. For the bull put 95/90, that is $500 plus the $41 long put, minus $135 of proceeds: $406 net, equal to the maximum loss. Spread treatment requires, among other conditions, that the short option expire on or before the long option and that both legs share the same underlying and exercise style. Under these rules, only spreads of European-style, cash-settled index options that expire together may be carried in a cash account. These are exchange minimums; firms may require more, and an assignment changes the position being margined.

Key takeaways

• A vertical spread is one long and one short option of the same type and expiration at different strikes. Buying the lower strike is bullish; buying the higher strike is bearish. Debit spreads lose at most the debit, credit spreads earn at most the credit, and the width caps the other side.
• For European options, a call debit spread and a put credit spread on the same strikes match after financing: the debit plus the credit equals the present value of the width. A high-probability put credit spread is an in-the-money call debit spread financed differently. The choice between them comes down to cash timing, quotes, and which legs carry early-exercise and dividend risk.
• Strike placement, not the label, sets the chance of profit, the payoff ratio, and the sign of theta and vega. A spread’s price divided by its width approximates the discounted risk-neutral probability of finishing beyond the middle of its strike range, so a higher chance of profit is paid for with a worse payoff ratio. Width decides how much of a single option’s exposure the spread keeps.
• No placement or version is better in general. Under the model each is fairly priced; real results depend on the actual move, implied volatility, costs, and assignment.
• Before expiration, a spread’s value moves only gradually toward its expiration payoff; a correct move early captures only part of the width.
• “Defined risk” assumes both legs settle together. Dividend-driven assignment, a deep in-the-money short put, or an expiration between the strikes can leave a stock position the payoff diagram does not show.

Primary sources

• Options Industry Council: Bull Call Spread · Bear Put Spread · Bull Put Spread · Bear Call Spread · Options Exercise FAQ · Equity vs. Index Options
• Options Clearing Corporation: Characteristics and Risks of Standardized Options
• FINRA: Exercise Cut-Off Time for Expiring Options
• Cboe: Margin Manual · Strategy-Based Margin
• Stoll, H. R. (1969). The Relationship Between Put and Call Option Prices. Journal of Finance, 24(5), 801–824.
• Black, F., and Scholes, M. (1973). The Pricing of Options and Corporate Liabilities. Journal of Political Economy, 81(3), 637–654.
• Merton, R. C. (1973). Theory of Rational Option Pricing. Bell Journal of Economics and Management Science, 4(1), 141–183.
• Breeden, D. T., and Litzenberger, R. H. (1978). Prices of State-Contingent Claims Implicit in Option Prices. Journal of Business, 51(4), 621–651.
• van Binsbergen, J. H., Diamond, W. F., and Grotteria, M. (2022). Risk-Free Interest Rates. Journal of Financial Economics, 143(1), 1–29.