Bull Call Spread

A bull call spread purchases a call and sells another call at a higher strike on the same underlying. Equal quantities, matching contract sizes, and a common expiration create a vertical spread with a net debit, limited maximum loss, and limited maximum profit. The higher-strike sale reduces the cost of the purchased call in exchange for offsetting further expiration gains above the short strike.

The position provides bullish exposure within a defined price range. It differs from a standalone long call because a sufficiently large rise no longer increases its expiration profit.

Construction and example

A hypothetical example uses SPY at $750 and calls with 45 days remaining. Purchasing one $750 call for $18.50 per share and selling one $775 call for $8.50 produces a $10 per-share net debit. With standard 100-share contracts, the spread costs $1,000.

The $850 received for the short call offsets part of the $1,850 purchase premium. The actual execution prices of the two calls determine the debit and resulting break-even.

Expiration payoff

At $750 or below at expiration, both calls have zero payoff and the $1,000 debit is lost. Between $750 and $775, only the lower-strike call has intrinsic value. Each additional $1 increase in SPY adds $100 to the spread’s payoff and reduces the initial loss.

The spread breaks even at $760, where the purchased call’s $10 per-share payoff recovers the debit. At $775, the lower call pays $25 per share and the higher call has zero payoff. The resulting $2,500 spread payoff, less the $1,000 cost, produces the maximum profit of $1,500.

Above $775, both call payoffs increase at the same rate. Their difference remains $25 per share, so profit remains $15 per share, or $1,500.

Moving the short strike further above the purchased strike permits a larger payoff difference, but usually reduces the premium received to offset the long call. Strike selection therefore changes the entry debit as well as the potential profit, and the two effects must be considered together.

Value before expiration

Closing the spread sells the lower-strike call and buys back the higher-strike call. A net closing receipt of $12 per share returns $1,200. Compared with the $1,000 entry debit, that realizes a $200 profit.

Both options can contain time value, so a closing price is not determined by current intrinsic value alone. With SPY above $775, remaining value in the short call can keep the spread’s sale value below its $25 expiration payoff. If SPY remains above both strikes as expiration approaches, the combined value converges toward that width. If SPY remains below $750, it converges toward zero instead.

The legs have different sensitivities to underlying price, time, and implied volatility. A common volatility increase raises both call values but does not necessarily raise their difference. The net effect changes as SPY moves through the strikes, and the IVs at the two strikes need not change equally. The spread’s early result consequently depends on both available option prices.

Exercise, assignment, and execution

SPY calls permit early exercise. Assignment of the short $775 call sells 100 shares at $775 while the $750 call remains a separate purchase right. Exercising the long call to obtain shares for delivery realizes the $25 strike difference before the opening debit. Selling the long call and purchasing shares in the market may recover remaining time value when suitable prices are available.

At expiration between the strikes, the lower call may be exercised while the short call expires unused. The account can then retain 100 shares after the spread has ended. A later decline in those shares is outside the spread’s expiration loss calculation. Early assignment can likewise create interim funding or delivery requirements even while the long call remains protective.

A complex closing order can trade the two option legs at a specified net price and ratio. It preserves the intended one-to-one quantities for each filled package but may leave part or all of the order unfilled. The options retain separate exercise and assignment treatment regardless of how the opening order was executed.

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 final underlying price. The long call payoff is added, the short call payoff subtracted, and the debit deducted. For $q$ complete spreads with multiplier $M$:

For a positive debit smaller than the strike width:

The break-even lies between the strikes, where the long call’s intrinsic value equals the debit. Above both strikes, the fixed payoff difference gives the profit cap; below both, the zero payoff gives the debit loss. Increasing the number of complete spreads scales these dollar amounts without changing the break-even or one-to-one offset.