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Vega Hedge with Calendar Spreads: A Term-Structure Plan

For educational purposes only; not investment advice.

Direct answer

Section titled “Direct answer”

A calendar-spread Vega hedge uses options with different expirations to change a portfolio’s sensitivity to implied volatility by maturity. A common long calendar sells a nearer option and buys a farther option of the same type and strike. Because the farther option often has greater Vega, the spread is frequently net long Vega at entry.

That net number is only a parallel-shift estimate. The near and far IVs are separate surface points and can move by different amounts. A calendar can reduce aggregate Vega while adding term-structure basis risk, front-expiry Gamma, Theta, Delta, liquidity, and assignment exposure. A hedge plan therefore needs expiry buckets and full scenarios, not just “net Vega near zero.”

Hedge construction

Section titled “Hedge construction”

First normalize every leg to dollars per one volatility-point move:

position Vega = displayed per-share Vega × signed contracts × multiplier

Then group Vega by expiration and, where material, by strike or Delta. Report both gross and net values. For a proposed calendar:

calendar Vega = far-leg Vega − near-leg Vega

For a simple parallel-shift target, an initial integer hedge count is:

calendar count ≈ (target net Vega − current net Vega) ÷ Vega per calendar

Round toward the risk limit, not mechanically to the nearest contract, and recalculate Delta, Gamma, Theta, margin, and liquidation value after adding the spread. A ratio that neutralizes today’s Vega becomes stale when spot, IV, time, or either leg’s moneyness changes.

Next replace the parallel assumption with a scenario matrix. Shock near IV and far IV independently, move spot toward and away from the strike, advance the clock, widen Bid/Ask spreads, and reprice both legs. Include the short option’s expiration and the decision to close, roll, accept settlement, or retain the far option. A roll closes one hedge and opens another; it is not a continuation at unchanged risk.

Parallel and nonparallel IV examples

Section titled “Parallel and nonparallel IV examples”

Suppose one long calendar has far-leg Vega +$0.145 and short near-leg Vega −$0.082 per share per volatility point. With a 100-share multiplier:

net Vega per calendar = ($0.145 − $0.082) × 100 = +$6.30 per point

A portfolio has net Vega −$126 per point under a parallel-shift summary. Ignoring integer and other risks for the first pass, 20 calendars add 20×$6.30=+$126, producing approximately zero aggregate Vega.

But the hedge contains gross far Vega of +$290 and gross near Vega of −$164 per point. If both expirations rise 4 points, the calendar package’s Vega-only estimate is:

20 × 100 × [($0.145×4) − ($0.082×4)] = +$504

If near IV rises 7 points while far IV rises only 2, the same package estimate is:

20 × 100 × [($0.145×2) − ($0.082×7)] = −$568

The package labeled “long Vega” loses in the second scenario because the short bucket moves more. These are local estimates; changing Vega, spot, skew, time, and execution require full repricing. The original portfolio’s bucket exposures must be shocked alongside the hedge before judging effectiveness.

Operational hedge plan

Section titled “Operational hedge plan”
  • Inventory every option, stock position, multiplier, expiry, strike, exercise style, and signed quantity from broker records.
  • Normalize Vega to one volatility point and dollars, then split it into near, event, medium, and long-dated buckets.
  • Identify the actual risk to reduce: a parallel shift, one event expiry, a term-slope move, or a specific strike region.
  • Select liquid calendar legs that overlap that risk. Similar net Vega in unrelated expirations may be a poor hedge.
  • Calculate an initial ratio, round to tradable contracts, and report remaining net and gross Vega.
  • Fully reprice spot gaps plus near/far IV shocks; do not add Greek estimates across large moves as if they were constant.
  • Check Delta, Gamma, Theta, Vomma, skew, margin, debit, maximum stress loss, and executable Bid/Ask after the hedge.
  • Set review triggers based on bucket Vega, spot distance from strike, days to front expiry, event dates, spread width, and stress loss.
  • Before front expiry, decide whether to close both legs, close or roll the short leg, or retain the far option. Re-underwrite every roll.
  • For American equity options, monitor early assignment, especially deep-in-the-money short Calls near an ex-dividend date.
  • Do not assume the far option automatically covers assignment. Exercise, assignment, stock delivery, and broker cutoffs are separate processes.
  • Record hedge slippage and realized P&L by Delta, time, surface, and execution so an ineffective basis hedge is not repeatedly renewed.

Common misconceptions

Section titled “Common misconceptions”
  • “Net Vega zero means volatility-neutral.” Separate expirations and strikes can move differently while gross exposure remains large.
  • “A calendar is always long Vega.” Its sign and magnitude change with spot, time, moneyness, and model inputs.
  • “Longer-dated IV rising helps regardless of spot.” Delta, Gamma, skew, and moneyness changes can outweigh the Vega estimate.
  • “The short leg provides free Theta.” Front Gamma, event jumps, assignment, and liquidity are the price of that decay exposure.
  • “One hedge ratio works until expiration.” All Greeks and the surface change continuously.
  • “Rolling preserves the hedge.” A roll realizes one position and creates a new contract with new risk and cost.
  • “Midpoint Greeks describe executable protection.” Wide or asynchronous quotes can make the hedge expensive or unavailable when needed.
Section titled “Related topics”

Authoritative sources

Section titled “Authoritative sources”