Options Academy
Diagonal Bull Spreads 102: Payoff Map and Re-Write Edge
A diagonal bull spread can improve flat-to-mild outcomes and allow a second short-call sale, reducing effective basis over time.
Example Setup (30/35 Structure)
Assume XYZ is at 32. Prices: April 30 call = 3, April 35 call = 1.5, July 30 call = 4.
Vertical bull spread: buy Apr 30, sell Apr 35 -> 2-point debit.
Diagonal bull spread: buy Jul 30, sell Apr 35 -> 3-point debit.
Underlying
XYZ = 32
Vertical Cost
2.0 debit
Diagonal Cost
3.0 debit
Short Strike
35 (near-term)
Near-Term Expiry Comparison
If XYZ rallies well above 35 by April expiry, the vertical often has higher immediate profit.
If XYZ stays in a middle zone, the diagonal long July call can retain extra time value and reduce relative loss.
In the cited pricing table, diagonal outcomes were often better than vertical around roughly 27-32.
Vertical vs Diagonal Bull Spread at Near Expiry (Illustrative)
- diagonal
- vertical
The Re-Write Advantage
After April expiry, if stock is still below 35, you can sell the next call (for example Jul 35) against the long Jul 30.
That second sale can reduce your effective basis and convert the position toward a standard bull spread with improved entry economics.
This path-dependent edge is one of the main practical reasons to diagonalize.
Basis Math: Did the Re-Write Help?
Use this checkpoint formula: Effective Basis = Long Cost - Short Premium #1 - Short Premium #2.
With the example path: buy Jul 30 for 4.0, sell Apr 35 for 1.0, then sell Jul 35 for 1.0 -> effective basis = 4.0 - 1.0 - 1.0 = 2.0.
If direct July vertical entry would cost more (for example 2.5), diagonalizing plus rewrite has created a better basis.
Long Jul 30 Cost
4.0 debit
Apr 35 Premium Collected
-1.0
Jul 35 Premium Collected
-1.0
Effective Jul Bull Basis
2.0
Execution Rules of Thumb
Rule 1: if price is clearly above short strike near expiry, prefer taking profits rather than forcing a rewrite.
Rule 2: if price is between long and short strikes, evaluate rewrite to lower net cost.
Rule 3: if price is deeply below long strike, decide whether to close or hold long call as standalone exposure.
Key takeaways
- Diagonal bull spreads can outperform verticals in some flat-to-moderate paths.
- They often underperform verticals on sharp immediate upside.
- The second short-call sale is a key source of edge.
- Treat management decisions at near-term expiry as part of strategy design.
Series
Diagonal Spread Masterclass
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