Implied Volatility (IV)

What is Implied Volatility (IV)?

Implied Volatility (IV) Implied volatility (IV) is the market's forecast of how volatile a stock will be over the life of an option, expressed as an annualized standard deviation. If a stock has 25% IV on a 30-day option, the market expects the stock's annualized volatility to be 25% over the next 30 days — which translates to a one-standard-deviation move of approximately 7.2% (25% / sqrt(12)) over the option's life. IV is derived from the market price of the option, not from historical data. Given the option's market price, strike, time to expiration, stock price, and risk-free rate, you can solve the Black-Scholes (or other pricing model) equation backward to find the implied volatility — the volatility input that would produce the observed market price. Hence "implied" volatility: it's implied by the price the market is paying. IV differs from realized volatility (RV), which is the actual historical price movement of the stock. The difference between IV and RV is the volatility risk premium (VRP) — typically positive on equity indices, meaning option sellers earn a structural premium over time as IV consistently overshoots actual realized vol. IV is not constant across strikes or expirations. The variation across strikes is the volatility skew (typically with OTM puts more expensive than OTM calls on equity indices, reflecting crash-risk premium). The variation across expirations is the term structure (typically upward-sloping in calm markets, inverting during stress). Levels of IV vary widely by underlying: - SPY typically trades 12-25% IV in normal regimes - Single mega-caps (AAPL, MSFT) typically 18-35% - High-volatility names (TSLA, NVDA) typically 35-70% - Speculative biotech or meme stocks can run 100%+ - VIX is the most-quoted IV measure; tracks 30-day ATM SPX IV IV moves with market regime. It expands sharply during sell-offs and contracts during quiet uptrends. Earnings announcements cause IV to spike days before, then crash immediately after (the IV crush). Macro events (FOMC, CPI releases, geopolitical shocks) drive temporary IV expansions. For traders, IV rank or IV percentile is more useful than the absolute IV level. IV rank of 75 means the current IV is in the top quarter of its 52-week range — signaling rich premium to sell. IV rank of 15 signals cheap premium to buy. These normalized metrics are far more actionable than raw IV numbers, which vary enormously by underlying.