Academy/Advanced Quant/Options Pricing & The Greeks
Advanced QuantLesson 1

Options Pricing & The Greeks

Understand how options are priced and the five Greeks that measure different dimensions of risk.

14 minute read
5 key takeaways

Options Pricing: The Foundation

Options are priced according to the Black-Scholes model, which uses five inputs to determine fair value. Understanding these is essential for algorithmic options trading.

Black-Scholes Formula

C = S×N(d₁) - K×e^(-rT)×N(d₂)

Where d₁ and d₂ are complex functions of S, K, r, T, and σ

The five inputs:

  • S = Current stock price
  • K = Strike price
  • T = Time to expiration (in years)
  • r = Risk-free rate
  • σ = Implied volatility (the market's guess of future volatility)

The Five Greeks

GreekMeasuresRangeTrading Use
Delta (Δ)Price change per $1 move in stockCall: 0-1, Put: -1-0Directional exposure
Gamma (Γ)Rate of delta change0 to Max at ATMOptions: gamma risk
Theta (Θ)Daily time decayNegative for buyersExpect daily loss for long options
Vega (ν)Sensitivity to implied volatilityPositive for longBet on volatility changes
Rho (ρ)Sensitivity to interest ratesUsually smallLess important for trading
python
from scipy.stats import norm
import numpy as np

def black_scholes(S, K, T, r, sigma):
    d1 = (np.log(S/K) + (r + 0.5*sigma**2)*T) / (sigma * np.sqrt(T))
    d2 = d1 - sigma * np.sqrt(T)

    call_price = S * norm.cdf(d1) - K * np.exp(-r*T) * norm.cdf(d2)
    delta = norm.cdf(d1)
    gamma = norm.pdf(d1) / (S * sigma * np.sqrt(T))
    vega = S * norm.pdf(d1) * np.sqrt(T) / 100  # Per 1% change in vol
    theta = (-S * norm.pdf(d1) * sigma / (2*np.sqrt(T)) - r*K*np.exp(-r*T)*norm.cdf(d2)) / 365

    return call_price, delta, gamma, vega, theta

# Example: AAPL $150 call, stock at $148
S, K, T, r, sigma = 148, 150, 30/365, 0.05, 0.25
price, delta, gamma, vega, theta = black_scholes(S, K, T, r, sigma)

print(f"Call price: ${price:.2f}")
print(f"Delta: {delta:.3f}  (price moves $0.72 if stock moves $1)")
print(f"Gamma: {gamma:.4f}  (delta changes by this much if stock moves $1)")
print(f"Vega: {vega:.2f}   (price changes $0.23 if IV changes 1%)")
print(f"Theta: ${theta:.3f}  (loses $0.02 per day from time decay)")

IV Rank & IV Percentile

Implied Volatility (IV) at this very moment—where does it sit in its 52-week range?

  • IV Rank > 50: Options are expensive relative to history
  • IV Rank < 50: Options are cheap relative to history
  • Buy options when IV Rank < 30 (cheap)
  • Sell options when IV Rank > 70 (expensive)

Portfolio Greeks

Your portfolio delta, gamma, theta, vega are the sums of your positions. Manage them as a portfolio, not individual options.

Practical Tip: Watch Theta Daily

For short options strategies (covered calls, sells), theta is your profit engine. Each day, time decay puts money in your pocket. Watch it daily to ensure decay is on your side.

Key Takeaways
  • Black-Scholes model prices options based on 5 inputs
  • Delta measures price sensitivity
  • Gamma measures delta sensitivity
  • Theta is time decay (friend to sellers, enemy to buyers)
  • Vega measures volatility sensitivity