What is implied volatility?

Unlike historical volatility, which looks at how much price has moved, implied volatility looks forward: it captures how much movement the market is currently pricing in for the future. It is a single number that summarises collective expectations of uncertainty over an option’s remaining life.

IV is expressed as an annualised percentage, but it directly affects the cost of options on Nifty, Bank Nifty, and individual NSE stocks. Because IV reflects expected movement in either direction, it is symmetric — it does not say whether the market expects a rise or a fall, only that it expects a move of a certain size.

Option prices depend on several inputs: the underlying price, the strike, time to expiry, interest rates, and volatility. Of these, every input except volatility can be observed directly. So traders run the logic in reverse: given the option’s actual market premium and all the known inputs, what volatility figure does the model require to produce that price? That figure is the implied volatility.

This is why IV is described as implied — it is implied by the premium that buyers and sellers have agreed on. When demand for options rises, premiums rise, and the IV needed to justify them rises with them. When option demand cools, premiums and IV fall. IV therefore behaves like a market-set price for uncertainty.

Because IV moves up and down over time, traders usually judge it relative to its own recent range rather than against an absolute threshold. IV tends to climb ahead of known uncertain events — company results, major policy announcements, or scheduled data — as participants pay up for protection, and it often falls sharply once the event passes and uncertainty resolves, a pattern frequently described as a volatility “crush”.

The key relationship to internalise is between IV and premium: when IV is high, option premiums are richer for the same strike and expiry; when IV is low, premiums are cheaper. Understanding this helps explain why an option can lose value even when the underlying moves in the buyer’s favour — a drop in IV can offset the gain from price.

IV does not predict the direction of the underlying. A high IV says the market expects a large move, not whether that move will be up or down. It is fundamentally a measure of expected magnitude.

IV is also not a forecast that has to come true; it is an expectation embedded in current prices, and realised movement can be larger or smaller. It does not tell you a stock’s fair value, and a high IV does not by itself make an option a good or bad purchase — that depends on whether the eventual move matches what was priced in.

A common error is buying options purely because the underlying is expected to move, without checking IV. If IV is already very high — for example just before results — a large part of the expected move may already be paid for, and the post-event IV drop can erode the option’s value even if price moves favourably.

Another mistake is treating high IV as a directional signal or as a guarantee of a big move; it is neither. A third is comparing raw IV across instruments without context, since each underlying has its own typical IV range. Reading IV relative to its own history, and remembering it is an expectation rather than a promise, keeps its meaning intact. None of this is a recommendation to trade options.