Guide détaillé à venir
Nous préparons un guide éducatif complet pour le Option Greeks Calculator. Revenez bientôt pour des explications étape par étape, des formules, des exemples concrets et des conseils d'experts.
Option Greeks are numerical measures that describe how sensitive an option's price is to changes in different market conditions — the underlying stock price, time passing, volatility, and interest rates. Think of them as the speedometer, fuel gauge, and weather readings of an options position all in one dashboard. Without Greeks, trading options is like driving without instruments. A trader who only knows the option price has no idea whether a $1 stock move will make or break their position, how much they lose each day simply from the clock ticking, or how a surge in market fear will affect their holdings. The five primary Greeks are Delta, Gamma, Theta, Vega, and Rho. Delta tells you the immediate directional exposure. Gamma tells you how rapidly that exposure is changing. Theta quantifies the daily cost of holding an option (time decay). Vega measures sensitivity to changes in implied volatility — critical before earnings, Fed announcements, and any major risk event. Rho, the least watched, measures interest rate sensitivity. Together the Greeks allow traders to construct precisely risk-managed positions, hedge books of options down to controlled exposure, and understand exactly what they are paying for when they buy an option. Market makers at major banks and exchanges use Greeks to hedge thousands of positions simultaneously and quote bid-ask spreads confidently. Individual traders use them to select which strikes and maturities offer the risk profile they want.
Delta (Δ) = ∂V/∂S ≈ N(d₁) for calls, N(d₁)−1 for puts Gamma (Γ) = ∂²V/∂S² = N'(d₁) / (S·σ·√T) Theta (Θ) = ∂V/∂t (negative for long options — daily time decay) Vega (ν) = ∂V/∂σ = S·N'(d₁)·√T (per 1-point σ change) Rho (ρ) = ∂V/∂r = K·T·e^(−rT)·N(d₂) for calls
- 1Calculate all Greeks analytically using Black-Scholes partial derivatives, or read them directly from your broker's options chain — most platforms display them for every listed option.
- 2Use Delta to estimate your P&L for a stock price move: ΔP&L ≈ Delta × ΔS. A delta of 0.55 means you gain approximately $0.55 per $1 the stock rises.
- 3Add Gamma for accuracy on larger moves: ΔP&L ≈ Delta × ΔS + ½ × Gamma × ΔS². Gamma is especially important for short-dated options where delta changes rapidly.
- 4Monitor Theta daily: if you hold long options worth $10,000 and your portfolio Theta is −$150/day, you lose $150 of time value each day regardless of stock price movement.
- 5Watch Vega before binary events: if you hold a long call with Vega = $0.12 and implied volatility collapses from 35% to 25% (−10%), you lose $1.20 per option from vol crush alone — even if the stock moves in your favour.
- 6Hedge using Greeks: a delta-neutral position (net delta ≈ 0) profits from large moves regardless of direction. A vega-neutral position is unaffected by volatility changes.
This is a first-order approximation; add ½ × Gamma × 9 × 1,000 for precision.
Delta is essentially a first-order hedge ratio. If you had sold 600 shares (delta × shares = 0.60 × 1,000) against this option position, your net delta would be zero and the $3 stock move would produce approximately zero net P&L — a delta hedge.
This loss occurs purely from time passing — even if the stock price doesn't move at all.
At-the-money options have the highest absolute theta. This is the fundamental tension in option buying: you need the stock to move enough to offset the daily erosion. A $200 weekly time decay means the stock must move far enough to generate at least $200 in delta P&L just to break even on the week.
Even if the stock moves significantly, vol crush can wipe out the gain from delta — a classic 'buy the rumour, sell the news' trap.
This is one of the most painful experiences for new options traders: buying options before an expected event, being right about the direction, but still losing money because implied volatility collapses after the uncertainty resolves. The stock might move $5 (generating $2,500 in delta P&L) but $4,500 is lost to vol crush — net loss of $2,000.
Market makers with long gamma profit from stock price oscillation by continuously re-hedging — 'scalping' the gamma.
Long gamma positions gain from large stock moves in either direction. A market maker who is long gamma will buy stock when it falls (delta becomes more negative) and sell when it rises (delta becomes more positive), locking in small profits on each oscillation. This is gamma scalping — the premium paid for the option is funded by these realised profits if actual volatility exceeds implied volatility.
Delta hedging by market makers to maintain market-neutral books, where accurate option greeks analysis through the Option Greeks supports evidence-based decision-making and quantitative rigor in professional workflows across diverse organizational contexts and analytical requirements
Selecting option strikes and expiries based on desired risk profile, where accurate option greeks analysis through the Option Greeks supports evidence-based decision-making and quantitative rigor in professional workflows across diverse organizational contexts and analytical requirements
Managing portfolio-level Greeks for risk limits at banks and hedge funds, where accurate option greeks analysis through the Option Greeks supports evidence-based decision-making and quantitative rigor in professional workflows across diverse organizational contexts and analytical requirements
Structuring protection strategies (collars, protective puts) using delta as the hedge ratio, where accurate option greeks analysis through the Option Greeks supports evidence-based decision-making and quantitative rigor in professional workflows
Pin risk near expiry
When a stock closes exactly at the strike price on expiration day ('pinning the strike'), options are nearly impossible to hedge because delta flips between 0 and 1 with tiny price moves. Market makers face enormous gamma risk and often widen spreads significantly. Traders short options near expiry with the stock pinned at the strike face the risk of being randomly assigned — a common source of unwanted overnight stock positions.
Greeks for portfolio-level risk
Portfolio Greeks aggregate individual position Greeks: sum all deltas for total directional exposure (dollar delta = Δ × position size × stock price), sum gammas for total convexity, sum thetas for daily time decay. This portfolio-level view allows risk managers to see the net effect of all positions at once and identify concentrated exposures that need hedging.
Charm and speed: higher-order Greeks
Charm (∂Delta/∂t) measures how delta changes with time — important for delta hedgers who need to adjust their hedge as time passes even with no price move. Speed (∂Gamma/∂S) measures how gamma changes with price. These are used by sophisticated traders managing large option portfolios who rebalance frequently.
| Strike | Moneyness | Delta | Gamma | Theta ($/day) | Vega (per 1%) |
|---|---|---|---|---|---|
| $80 | Deep ITM | 0.97 | 0.003 | −$0.01 | $0.04 |
| $95 | Slight ITM | 0.72 | 0.032 | −$0.09 | $0.12 |
| $100 | ATM | 0.52 | 0.041 | −$0.12 | $0.14 |
| $105 | Slight OTM | 0.31 | 0.033 | −$0.09 | $0.12 |
| $120 | Deep OTM | 0.04 | 0.008 | −$0.02 | $0.03 |
What does it mean to be delta-neutral?
Delta-neutral means your total position has a net delta of approximately zero — you neither gain nor lose from small directional moves in the underlying stock. Options market makers strive to be delta-neutral at all times, hedging their options book with shares of the underlying. A delta-neutral position still has gamma, theta, and vega exposure — it profits or loses from large moves (gamma), time passing (theta), and volatility changes (vega).
Why does gamma peak for at-the-money options near expiry?
Gamma measures how rapidly delta changes. Near expiry, an at-the-money option's delta is highly uncertain — it could finish anywhere from 0 (out of money, worthless) to 1 (in the money, worth the full intrinsic value) with very little time for the situation to change. This uncertainty means even a tiny price move changes the probability dramatically, causing delta to shift rapidly. The result is extremely high gamma. This makes short-dated at-the-money options very risky to be short — a sudden move can create enormous delta exposure instantly.
What is vanna and volga and why do they matter?
Vanna (∂Delta/∂σ) measures how delta changes with volatility — important for hedging vol-correlated delta risk. Volga (∂Vega/∂σ) measures the convexity of option value to volatility — crucial for pricing and hedging exotic options and wings of the volatility surface. These 'second-order Greeks' matter for sophisticated option books but are rarely tracked by retail traders. They become important when managing large portfolios of options across different strikes and maturities.
How do I use Greeks to choose an options strategy?
Define what risk you want: directional (delta), event-driven (vega), or time-decay income (theta)? If you want to bet on a stock moving significantly in either direction, buy a straddle (long vega, long gamma). If you want income from a stable stock, sell covered calls or cash-secured puts (short theta, collecting premium). If you want leveraged directional exposure, buy in-the-money options (high delta). Greeks help you select the right instruments and strikes to express exactly the view you have.
What is the relationship between delta and the probability of profit?
Delta approximately equals the probability that the option expires in-the-money under the risk-neutral measure used by Black-Scholes. A call with delta 0.30 has roughly a 30% chance of expiring in-the-money at the current implied volatility. However, this is a risk-neutral probability, not a real-world probability — it does not account for any risk premium or directional bias. It is best used as a rough guideline for strike selection rather than a precise probability statement.
Why is theta negative for option buyers but positive for sellers?
When you buy an option, you pay a premium that includes time value — the possibility that the option could become more valuable with time remaining. As time passes, this possibility narrows, and the time value erodes. This erosion (negative theta) is a cost to buyers and a benefit to sellers. Covered call writers, put sellers, and credit spread traders deliberately harvest theta — they collect premium and profit as time value decays, as long as the stock doesn't move adversely.
How does rho affect LEAPS (long-dated options)?
For short-dated options (weeks to months), rho is negligible — interest rate changes have minimal impact. For LEAPS (options with 1–3 years to expiry), rho becomes significant. A 1% rise in interest rates can meaningfully increase call values and decrease put values because higher rates reduce the present value of the strike price. Calls benefit because you effectively defer paying the strike price; puts are hurt because the present value of what you'd receive by exercising is lower. With interest rates rising sharply in 2022–2023, rho gained renewed attention.
Conseil Pro
Before any options trade, write down your position's Delta, Theta, and Vega. Then ask: 'How much does the stock need to move to offset one week of theta?' This simple exercise prevents the most common options mistake: paying for volatility you don't get.
Le saviez-vous?
Goldman Sachs uses thousands of options Greeks across millions of positions simultaneously. Their entire options risk management system essentially reduces to monitoring and hedging aggregated Greeks in real-time across global markets — a mathematical framework that didn't exist before 1973.