The equation looks intimidating, but it’s just a weighted average of past surprises:
The Black-Scholes model assumes constant volatility—which traders know is false. GARCH-based option pricing models (e.g., Heston-Nandi) better capture the volatility smile. arch models
Big moves tend to be followed by big moves (in either direction), and quiet periods tend to be followed by quiet periods. If you plot the S&P 500 or Bitcoin returns, you don’t see random scatter. You see pockets of chaos and pockets of calm. The equation looks intimidating, but it’s just a