Net Greeks — Reading the Risk of Multi-Leg Positions
How to compute net Delta, Gamma, Theta, and Vega for any combination of options. The skill that separates serious traders from premium guessers.
Every multi-leg option position has net Greeks that are just the sum of the individual leg Greeks, weighted by contracts per leg. Net Delta tells you your directional exposure. Net Gamma tells you how that exposure shifts as the market moves. Net Theta tells you your daily decay. Net Vega tells you your IV exposure.
Reading net Greeks is the difference between trading multi-leg positions blind and trading them with full risk awareness. Every position type has a recognisable Greeks signature — once you can read it, the strategy stops being a name and becomes a risk profile.
Long straddle — the volatility bet
Buy ATM call + buy ATM put. Net Delta ≈ 0 (calls +0.50 + puts -0.50). Net Gamma is high and positive (both legs are long Gamma). Net Theta is very negative (paying two premiums). Net Vega is high and positive (both legs are long Vega).
Reading the profile: directional-neutral at entry, profits if the underlying moves in EITHER direction enough to overcome combined premium, bleeds Theta every day, benefits from IV expansion. Classic pre-event trade.
Short strangle — the income trade
Sell OTM call (say 1% above spot) + sell OTM put (say 1% below spot). Net Delta ≈ 0. Net Gamma is negative (you're short two long-Gamma options). Net Theta is high and positive (you're collecting two premiums of decay). Net Vega is negative (IV expansion hurts you).
Reading the profile: directional-neutral if the underlying stays in range, profits from time decay and IV crush, but unlimited loss if either side breaks out. Most popular Indian income strategy on weekly options.
Iron condor — defined-risk income
Sell OTM call + buy further-OTM call (call credit spread) + sell OTM put + buy further-OTM put (put credit spread). Like a short strangle but with the tails protected by longer-strike longs.
Net Delta ≈ 0. Net Gamma is slightly negative. Net Theta is positive (smaller than short strangle because you're paying for the wing protection). Net Vega is slightly negative.
Reading the profile: same upside as short strangle but with defined max loss = spread width minus credit collected. Lower reward, much lower risk. Most disciplined version of income selling.
Calendar spread — Vega and Theta differential
Sell near-dated option + buy same-strike longer-dated option. Net Theta is positive (near-dated decays faster than longer-dated). Net Vega is positive (longer-dated has more Vega than near-dated). Net Delta is slightly positive or negative depending on strike vs spot.
Reading the profile: profits when the underlying stays near the strike (Theta differential maximised at ATM) AND when IV rises (Vega positive). Best in sideways, low-IV markets ahead of a known catalyst.
Common misreads
- Treating multi-leg positions as 'safer' because there are more legs. Net Greeks determine risk, not leg count. A 4-leg iron butterfly can have more concentrated risk than a simple long call.
- Forgetting that Greeks change as the market moves. Net Delta is zero at entry on a straddle, but after a 1% underlying move, Delta becomes meaningfully positive or negative.
- Sizing multi-leg positions by premium collected. Better metric: net Vega and net Theta — they tell you your IV exposure and daily income directly.
Key takeaways
- Net Greeks = sum of each leg's Greeks × contracts per leg.
- Long straddle: zero Delta, long Gamma, short Theta, long Vega (volatility bet).
- Short strangle: zero Delta, short Gamma, long Theta, short Vega (income trade).
- Iron condor: same shape as short strangle but defined risk.
- Calendar spread: long Vega + long Theta — best in sideways pre-event markets.
Multi-leg risk reading
I have 2 lots of a 0.40 Delta call and 1 lot of a 0.30 Delta put. What's my net Delta?
Net Delta = 2 × (+0.40) + 1 × (-0.30) = 0.80 - 0.30 = 0.50. The position is moderately bullish — every 100-point NIFTY rise produces +0.50 × 25 × 100 = ₹1,250 of P&L change (before Gamma adjusts the Delta).
What's the difference between an iron condor and a strangle?
Strangle = sell OTM call + sell OTM put (2 legs). Iron condor = same but ADD long calls and long puts even further OTM as wings (4 legs). The wings cap max loss but reduce premium collected. Iron condor is 'strangle with seatbelts'.
When is a calendar spread better than buying a straight option?
When you expect IV to rise AND the underlying to stay near a specific strike. The calendar harvests Theta differential and benefits from Vega expansion. Straight long options bleed Theta on quiet days; calendars don't.
Why do my position Greeks change minute-to-minute even when I haven't traded?
Three reasons: (1) spot moves change Delta via Gamma, (2) IV moves change Vega via Vomma, (3) time passing changes everything via Theta. Greeks are dynamic — they're snapshots of current risk, not fixed properties of your position.
Should I use net Greeks to set stops?
Better: use net P&L at adverse-scenario prices. Set the stop on dollar loss, not Greek values. Greeks predict P&L change but the actual loss includes path-dependent effects too.