Implied Volatility — Pricing the Unknown
IV is the market's estimate of how volatile the underlying will be from now to expiry. The single most important non-direction column.
IV = Implied Volatility. Derived from the option's market price, it tells you the market's expectation of how volatile the underlying will be over the option's remaining life.
Higher IV = more expensive options. Lower IV = cheaper options. IV regime determines whether to buy or sell premium.
Where IV comes from
Reverse-engineered from the option's market price using Black-Scholes. Given the price, spot, strike, time, and risk-free rate, you solve for the volatility that makes the formula match the market price.
Strota's chain shows IV per strike, calculated from the LTP.
Reading IV regime
NIFTY ATM IV typically: 12-18% calm, 18-25% volatile, 30%+ around major events.
Compare today's IV to its 90-day percentile distribution. Bottom 20% = buying premium edge. Top 20% = selling premium edge.
BANK NIFTY IV runs ~30-50% higher than NIFTY at any given time.
Common misreads
- Treating IV percentages across markets as comparable. NIFTY at 14% and BANK NIFTY at 22% may both be 'normal' for their markets.
- Buying premium just because IV looks 'low' in absolute terms. Check percentile distribution.
Key takeaways
- IV = market's expectation of underlying volatility.
- Higher IV = more expensive options.
- Compare IV to 90-day percentile, not absolute level.
- Bottom percentile favours buyers; top favours sellers.
IV reading
What's a 'high' NIFTY IV?
Above 25% is high in modern Indian markets. Anything above 30% is event-driven (catalysts approaching) — IV typically crushes back to 14-18% within days of the event.
Why is IV higher on stock options than index?
Single-stock realised volatility is higher than index (concentration risk). Stock IV typically runs 25-50% above index IV for most names.
Does IV predict future moves?
Indirectly. IV is forward-looking market expectation. Actual realised volatility often diverges. The divergence is the trade — buy IV when it's cheaper than realised, sell when it's pricier.