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AcadiFi
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StrikePriceSam2026-05-20
cfaLevel IIDerivativesOption Strategies

What changes in my calculations when one leg of a bull spread is short?

I understand the intuition of a bull spread, but I still make sign mistakes once the higher-strike call is written instead of purchased.

41 upvotes
Verified ExpertVerified Expert
AcadiFi Certified Professional

The short leg turns part of the upside into a negative payoff for your strategy once that option finishes in the money.

Example with Harbor Vision Media:

  • Long call, strike 65, premium 5
  • Short call, strike 75, premium 2

If the stock ends at 82:

  • Long 65 call value = 17
  • Short 75 call value = -7
  • Net expiration value = 10

Then include premiums:

  • Net premium paid = -5 + 2 = -3
  • Profit = 10 - 3 = 7

The short higher-strike call does two things:

  • It lowers the upfront cost.
  • It caps the payoff beyond the higher strike.

That is why the bull spread is cheaper than a naked long call, but it also gives up unlimited upside.

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