Bull Call Spread

A bull call spread, or call debit spread, buys a call and sells another at a higher strike. Both calls use the same underlying and expiration, equal quantities and matching contract multipliers. The short call helps pay for the long call, but caps the upside: unlike a standalone long call, the spread earns no additional expiration profit above the higher strike.

A $750/$775 SPY spread

With SPY at $750 and 45 days until expiration, suppose you buy one $750 call for $18.50 per share and sell one $775 call for $8.50. Each contract covers 100 shares. You pay $1,850 for the long call and receive $850 for the short call, leaving a $10 per-share net debit, or $1,000 for the spread.

The graph uses these hypothetical premiums. Opening the scenario in the calculator instead prices the legs from its inputs and date, with no actual-fill input. A real trade’s execution prices determine the debit and break-even, and costs reduce its net result.

Expiration payoff

At $750 or below, both calls have zero intrinsic value at expiration, so the spread loses the $1,000 debit. Between $750 and $775, only the long call has intrinsic value; each $1 rise adds $100 to the spread’s payoff. It breaks even at $760, where that payoff reaches $1,000.

At $775, the long call has $25 per share of intrinsic value and the short call has none. The spread’s $2,500 payoff, less its $1,000 cost, gives a $1,500 maximum expiration profit, before costs. Above $775, both call payoffs rise at the same rate. Their difference stays at $25 per share, leaving the same $15 per-share profit, or $1,500.

Moving the short strike higher widens the spread but usually brings in less premium to offset the long call. It changes both the potential payoff and what you pay for it; a wider spread is not simply extra upside at the same cost.

Closing before expiration

To close, sell the lower-strike call and buy back the higher-strike call. If you can do that for a $12 per-share net receipt, you receive $1,200 and make $200 on the original $1,000 debit, before costs.

Even with SPY above $775, the short call can have more time value than the long call. Buying it back then leaves a net receipt below the $25 strike width. The worked example in debit spread value before expiration explains that difference using both option prices.

If SPY stays above both strikes as expiration approaches, the spread’s value converges toward $25 per share. If it stays below $750, value converges toward zero. Waiting therefore does not help every bull call spread.

A common rise in implied volatility generally increases both call values, but it need not increase their difference. The effect depends on each leg’s sensitivity at the current underlying price, and actual implied volatilities at the two strikes need not change together. The early result depends on both available prices.

What happens if the short call is assigned?

SPY calls are American-style and may be exercised before expiration. Assignment of the short $775 call requires you to sell 100 shares at $775. The $750 long call remains a separate contract; assignment does not automatically exercise it.

Exercising the long call buys 100 shares at $750 for delivery, realizing the $25 strike difference before the opening debit and costs. Selling the long call and buying shares in the market may instead preserve its remaining time value, depending on available prices. Assignment can create interim funding or delivery requirements even while the long call remains available.

The legs can also end differently at expiration. If SPY finishes between the strikes, the long call may be exercised while the short call expires unused, leaving 100 shares in the account. A later decline in those shares is outside the spread’s $1,000 expiration-loss limit.

A complex closing order specifies a net price and one-to-one ratio. Each filled package preserves that ratio, although part or all of the order may remain unfilled. The calls still retain separate exercise and assignment treatment.

Payoff formulas

Let $K_L$ be the lower purchased strike, $K_H$ the higher short strike, $d$ the net debit per share and $S_T$ the underlying price at expiration. For $q$ complete one-to-one spreads with multiplier $M$ , add the long call’s payoff, subtract the short call’s payoff, then deduct the debit:

\text{P/L}=qM\bigl[\max(S_T-K_L,0)-\max(S_T-K_H,0)-d\bigr]

The following expiration limits assume $0<d<K_H-K_L$ and exclude costs:

\text{Maximum loss}=qMd

\text{Maximum profit}=qM(K_H-K_L-d)

\text{Break-even}=K_L+d

Increasing the number of complete spreads scales dollar gains and losses, not the break-even price or the one-to-one offset.