Implied move vs. realized move: how to compare an option market's range

The common event convention uses the at-the-money straddle: add the call and put mid prices at the same strike and expiration. If each is quoted at $3.10, the straddle is $6.20, so a simple one-standard-deviation-style range around a $100 underlying is approximately $93.80 to $106.20. The calculation is a market convention, not a universal probability statement.

Options expected move covers alternative conventions, including volatility-based estimates and the difference between a range and a probability. Confirm the strike, expiration, quote time, and whether the values are mid, bid, or ask.

Choose the same start and end timestamps used for the implied estimate. For an absolute move, calculate:

`abs(end price - start price)`

For a percentage move, divide that result by the start price. If an event begins with the underlying at $100 and it closes at $104, the absolute move is $4 and the percentage move is 4%. A high intraday excursion that closes near $100 is a different result from a sustained $4 move, so decide whether the review uses close-to-close, high-low, or path-aware data.

Realized volatility calculation is useful when the question is not one event's endpoint but the dispersion of returns over many observations.

Suppose an earnings straddle costs $6.20 with the stock at $100. The simple implied range is $93.80–$106.20. After earnings, the stock trades at $103.50:

1. The close-to-close realized move is $3.50, or 3.5% 2. It is inside the $6.20 implied range, but the straddle buyer can still lose money because premium also paid for volatility and time 3. If the stock touched $108 intraday and closed at $103.50, a close-only comparison hides the path and the hedge opportunities

Earnings option volatility explains why the implied range can shrink after the event even when the underlying moves.

For a long straddle, the rough expiration break-even prices are strike plus and minus the premium, before fees and execution effects. An underlying ending inside that interval may leave the position unprofitable even if it moved meaningfully. For a short straddle, an inside-range result can help the seller, but gap, margin, assignment, and tail risk remain.

The implied move also uses option prices that embed skew, supply and demand, interest rates, dividends, and liquidity. It is not a pure forecast of the median outcome. Implied volatility provides the broader context.

Use a repeatable record:

Compare a sample, not one headline event. A realized move below the implied move is evidence about that observation, not proof of a permanent volatility risk premium. A move above it is not proof that buying options is always superior.

• underlying price, strike, expiration, and timestamp of the implied quote
• call, put, and straddle bid/mid/ask values
• event window and the exact realized-price convention
• fees, spread, hedge trades, and any position adjustment
• whether the question concerns one event or a sample of events

The same endpoint can have very different risk. A fast gap followed by a reversal stresses a short-gamma position differently from a slow drift. An IV change can make an option lose value after a move, while a volatility rise can cushion a smaller price move. IV crush vs. theta decay helps separate post-event effects.

This guide explains an options-market comparison for education. It is not a forecast or a recommendation. Market conventions, contract specifications, and executable quotes vary by venue.