Implied Volatility: What Option Prices Say About Expected Moves
Implied volatility (IV) is a number hidden inside every option price: how big a move the market thinks might come. It never tells you up or down — only how large the market expects the move to be. The bigger the expected move, the more expensive the option.
What implied volatility is
IV is the market's expectation of future volatility: take an option's current market price, feed it into a pricing model, and solve backwards for the volatility that makes the model's price match the market's price. That number, expressed as an annualized percentage, is the IV.
IV is not observed directly — it is calculated: with the current price, the strike, the time to expiry, interest rates, and the option's actual traded price known, the model solves for the volatility figure that would produce that price.
IV speaks to the size of the move, never its direction: high IV only means the market expects a big move. The move could go up, down, or both over time. High IV is not a bullish signal, and it is not a bearish one either.
IV is not historical volatility: historical volatility measures how much the price actually moved in the past — it looks backwards. IV looks forwards. The two often disagree, and high IV does not mean the past was volatile.
How IV moves option prices
The examples below all use the same numbers: suppose the SPX is around 7,400 (these numbers are examples, not live quotes).
An option's price = intrinsic value + time value, and IV only moves time value. When IV changes, intrinsic value stays put; the time-value part is what moves.
All else equal, higher IV makes both calls and puts more expensive; lower IV makes both cheaper. The bigger the expected move, the more the "chance it could pay off" is worth.
IV often climbs before big events and collapses right after. Before earnings or a central-bank meeting, IV often rises; once the event is out and the uncertainty is gone, IV often falls sharply. That sudden drop is called IV crush (volatility crush).
You can get the direction right and still lose money. Buy an option, get the move right — but if the time value destroyed by IV crush is larger than the intrinsic value the move created, the option is still worth less than you paid for it.
Example: with the index at 7,400, the 7,400 call and the 7,400 put each sell for $50. Added together, $100 is roughly what the market is pricing in for a move of about 100 points in either direction before expiry. That is the implied move — a market expectation, not a promise that the index will actually move that far.
Simulate first, then talk about anything else
This simulator uses CBOE delayed quotes (about 15 minutes delayed), starts with $10,000 virtual cash, charges $0.65 per contract per side, and shows P&L net of fees. Its purpose is to practice order entry, discipline, and review. It is not investment advice and promises no returns.