The Earnings Implied Move and the Size of the Reaction

Open the option chain for a stock that reports tonight. Scroll to the first expiration after the report date and find the strike closest to the current price, the at-the-money strike, then read the call’s price and the put’s price at that strike and add the two together, which gives you a single number you can work out in seconds: the market’s estimate of how far the stock will move by that expiration, in either direction.

What the straddle prices

Owning the call and the put at one strike is a straddle. It pays if the stock moves far enough either way. It loses if the stock sits still.

So its price is roughly what option traders will pay for movement. In the expiration that spans a report, most of that movement is the report.

A few habits make the reading cleaner. Use the midpoint of the bid and the ask if the spreads are wide. Pick the nearest expiration after the report. Later ones fold in ordinary trading days and blur the event, and if the stock sits between two strikes, average the straddles at both.

The number has no direction in it. An 8% implied move means option traders are paying for an 8% swing and hold no view on which way it goes, so reading it as a forecast of a rise or a fall misreads what the market is selling you.

Where it shows on the chain

The event also shows up as implied volatility. The expiration that spans the report usually carries a higher implied volatility than the ones on either side of it, a bump in the volatility term structure that marks the date. Once the numbers are out, the bump goes. The extra value drains from the options, often within the first session, and traders call that fall volatility crush.

Comparing the reaction with the priced move

After the report, set the actual move against the priced one. That’s your measure of surprise.

Suppose the stock gaps 5%, to $157.50. The headline says big move. Against a priced 8% it was small. The market had braced for more.

For the straddle buyer, it’s a loss.

Buying options into a report is harder than it looks. You need a move bigger than the straddle cost, and the straddle was priced by people who knew about the report as well as you did. Before expiration the options keep a little time value, so the loss on the morning after may be slightly smaller, although most of the event premium has already gone the moment the numbers print and the uncertainty it was paying for disappears.

A move far past the priced one tells you something too. A 15% gap on an 8% implied move means the report changed the story, and analysts are likely to rewrite their models over the weeks that follow.

Turning it into money at risk

For a stock holder the implied move is a sizing tool. Multiply it by the position. The result is a rough loss from a move of the priced size going against you.

Too much to lose overnight? Then the position is too big for the report. The earnings gap loss calculator runs the same sum at different gap sizes, and the case for sizing a position held through earnings by the gap argues that this sum, and no hunch about direction, should set the share count you carry into the release.

The priced move gives you a yardstick for the morning after, and the last lesson deals with that morning: post-earnings drift, gaps and rechecking a position once the new price is on the screen.