Diagonal Call Spread Strategy
A diagonal spread using calls with different strikes and expirations. Buy a deep ITM call with longer expiration and sell an OTM call with shorter expiration. The deep ITM call mimics stock ownership while the short call generates income.
Overview
The diagonal call spread combines elements of both vertical and calendar spreads. You buy a deep in-the-money (ITM) call with a longer expiration (T') and sell an out-of-the-money (OTM) call with a shorter expiration (T).
The deep ITM long call has a high delta (close to 1.0), so it closely mimics owning the underlying stock. This provides protection against sharp rallies that would hurt a pure calendar spread.
Like a calendar spread, the strategy profits from time decay of the short call. However, the diagonal structure allows for more upside participation. If the stock rises past K₂, you benefit from intrinsic value gains in the long call.
Key Insight
Position Structure
Formulas
Key Insight
Deep ITM long call mimics stock ownership (high delta). More bullish than calendar spread. Can roll short calls monthly for income. Also called "poor man's covered call."
Research
Research on diagonal spreads, LEAPS strategies, and options-based equity exposure.
The Mathematics
In Plain English
The math behind this strategy is straightforward. Here's what you're actually doing:
- 1At entry: Pay a net debit (D). The deep ITM call is expensive but has high intrinsic value. The OTM short call partially offsets the cost.
- 2Key difference from calendar: The deep ITM long call (delta ≈ 1) moves almost dollar-for-dollar with the stock, providing upside protection.
- 3At short call expiration (t = T): Best case is S_T near K₂. Short call expires worthless, long call retains value (V).
- 4If stock rallies past K₂: You still profit because the long call gains intrinsic value faster than the short call liability.
That's it. The formulas below just express this process precisely.
1Maximum Profit (at short expiration)
V = value of long call when short call expires. Best when S_T = K₂ (short call expires worthless ATM).
2Maximum Loss
Occurs if stock drops significantly, making both calls worthless. Limited to the net debit paid.
3Net Debit
Cost of deep ITM long call minus premium from OTM short call. K₁ < K₂ (long is lower strike).
4Position Delta
Net delta is positive (bullish). Deep ITM call has delta near 1.0, OTM short call has lower delta.
LEAPS Strategy
A common implementation uses LEAPS (long-term options) for the long call, providing 1-2 years of exposure. Short calls are sold monthly against this position, similar to a "poor man's covered call."
Strike Selection
The long call should be deep ITM (delta > 0.80) to minimize extrinsic value and closely track the stock. The short call is typically 1-2 strikes OTM for optimal theta decay.
Strategy Rules
Position Setup
- 1Buy 1 deep ITM call with longer expiration (T', typically 6-12 months or LEAPS)
- 2Sell 1 OTM call with shorter expiration (T, typically 30-45 days)
- 3Long call strike K₁ should have delta > 0.80
- 4Short call strike K₂ typically 1-2 strikes above current price
- 5Verify net debit provides acceptable risk/reward
Entry Conditions
- 1Bullish outlook on the underlying
- 2Expect moderate upside through short expiration
- 3IV term structure favorable (not inverted)
- 4Sufficient liquidity in LEAPS if using long-dated options
- 5Stock ideally near support or consolidation zone
Risk Management
- 1Close if stock drops below long call breakeven
- 2Roll short call if it goes ITM before expiration
- 3Monitor delta exposure and adjust if needed
- 4Set stop-loss based on debit paid
- 5Watch for assignment risk on short call near ex-dividend
Exit Strategies
- 1Let short call expire worthless, then sell another
- 2Close entire position if thesis changes
- 3Roll short call to next month if still bullish
- 4Take profit if short call captures 50-75% of premium
- 5Close before earnings if position sizing is too large
Implementation Guide
The diagonal call spread is often called a "poor man's covered call" because it uses a deep ITM call instead of stock to generate covered call income with less capital.
Select the Underlying
Choose a stock or ETF with a bullish outlook. Ideal candidates are stable, liquid names where you'd be comfortable owning shares. Avoid high-volatility names where the long call could lose value quickly.
- Large-cap stocks and ETFs work best
- Look for names with consistent uptrends
- Ensure good options liquidity in LEAPS
Buy the Long Call (LEAPS)
Select a deep ITM call with at least 6-12 months until expiration. The strike should give delta > 0.80 so the option tracks the stock closely. LEAPS minimize theta decay on your long position.
- Delta > 0.80 ensures stock-like behavior
- Longer expiration = less time decay on long call
- Strike typically 10-20% below current price
Deep ITM calls have high intrinsic value but also require more capital. Ensure position sizing is appropriate.
Sell the Short Call
Sell an OTM call expiring in 30-45 days. Choose a strike 1-2 points above current price. This generates premium while allowing some upside participation.
- OTM strike gives room for stock to rise
- Monthly options have good liquidity
- Aim for 30-50% of long call cost from repeated sales
Manage and Roll
As short calls expire or are bought back, sell new short calls against the long position. Continue until the long call approaches expiration, then close or exercise.
- Roll when short call has lost 50-75% of value
- Adjust strike based on stock movement
- Track cumulative premium collected
Margin and Capital
Diagonal spreads require the net debit as capital. Since the long call covers the short call, margin requirements are minimal. This makes diagonals capital-efficient compared to covered calls on stock.
Helpful Tools & Resources
Strategy Variations
Explore different ways to implement this strategy, each with its own trade-offs and benefits.
Diagonal Put Spread
Bearish version using puts. Buy deep ITM put (long expiration), sell OTM put (short expiration). Profits from declining stock.
Calendar Call Spread
Same strike, different expirations. Less bullish exposure but simpler structure. ATM strikes maximize theta income.
Double Diagonal
Combine diagonal call and put spreads. Creates a wider profit zone but higher cost. Best for range-bound expectations with volatility.
Skip-Strike Diagonal
Wider gap between long and short strikes. More upside participation but less premium collected.
Risks & Limitations
If the stock drops significantly, the deep ITM call loses value. While limited to the debit paid, this can be substantial for LEAPS positions.
If the short call goes ITM, it may be assigned early (especially near ex-dividend). You would need to exercise the long call or close the position.
The long call (with more time) has higher vega. A drop in implied volatility hurts the position even if the stock stays flat.
LEAPS can have wider bid-ask spreads. This increases transaction costs and can make adjustments expensive.
Capital tied up in the long call could be deployed elsewhere. If stock stays flat for extended periods, returns may be suboptimal.
References
- Chaput, J. S., & Ederington, L. H. (2003). Option Spread and Combination Trading. Journal of Derivatives, 10(4), 70-88 [Link]
- Israelov, R., & Nielsen, L. N. (2015). Covered Calls Uncovered. Financial Analysts Journal, 71(6) [Link]
- Mixon, S. (2007). The Implied Volatility Term Structure of Stock Index Options. Journal of Empirical Finance, 14(3) [Link]
- Van Tassel, P. (2018). Equity Volatility Term Premia. Staff Reports, Federal Reserve Bank of New York [Link]
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