Buy one call, sell a higher one on the same expiry, and let the credit from the short leg pay down the debit on the long. Cost, breakeven and maximum loss all come down together; the profit stops dead at the upper strike. It suits a view that has a target attached to it — up, but to about here — and it is the usual answer when an outright call looks too expensive to justify. The mistake it invites is narrowness: a spread struck too close caps the gain before the expected move has finished running. Move the two strikes here and watch the debit and the ceiling trade against one another.
Two legs on one ticket, entered as a single 'vertical' order rather than as two separate trades — most platforms price and margin it that way, which avoids being filled on one leg and not the other in a moving market. The strike gap sets both the cost and the ceiling: a $5-wide spread behaves very differently from a $20-wide one at the same debit-to-width ratio. Compare the vertical's mid-price against the sum of the two legs' own mids; a wide bid/ask on the short leg alone can make the spread look cheaper than it fills.
The width is also a margin decision on some accounts: a cash-secured account needs the full debit and nothing more, since the risk is capped at what was paid, which is one reason this structure is often approved at a lower account tier than a naked short call would need. Scaling into the position by adding contracts as a thesis develops works less cleanly here than with a single option, because each new tranche has its own two fills and its own bid/ask cost. Held to expiry, both legs typically settle automatically if in the money; check the broker's auto-exercise threshold if the spread finishes only a few cents in the money.
Common mistake. The common mistake is setting the short strike at a round number that looks psychologically significant rather than at the level the underlying is actually likely to reach, capping the trade below its own thesis.
| # | Action | Instrument | Strike |
|---|---|---|---|
| 1 | Buy | Call | 580 |
| 2 | Sell | Call | 600 |
Computed from the same strikes and net premium as the worked example above — not a simulation, the closed-form payoff evaluated at each price.
| SPY at expiry | P&L |
|---|---|
| 560 | -$725.00 |
| 575 | -$725.00 |
| 590 | $275.00 |
| 600 | $1275.00 |
| 615 | $1275.00 |
| 630 | $1275.00 |
| Strategy | Market view | Opened for | Legs vs. this one |
|---|---|---|---|
| Long Call | Bullish — directional | Debit | -1 |
| Bull Put Spread | Bullish to neutral — income | Credit | same |
| Calendar Spread | Neutral — long volatility of time | Debit | same |
| Risk Reversal | Bullish — leveraged, undefined risk | Debit or credit | same |