How the Implied Earnings Move Is Calculated

The question the number answers

Before a company reports, one investor is trying to guess whether the news will be good or bad. Another has accepted that they cannot know, and is instead trying to work out how violent the reaction is likely to be.

The options market answers the second question continuously, and with real money. Every contract traded between now and the report is in part a bet on the size of the coming reaction, and options expiring just after the announcement are especially pure expressions of that bet. The implied move extracts that consensus and restates it as a single percentage.

The property most often misread is that the percentage is symmetric. When we report a 9% implied move, the options market is pricing a move of about 9% in either direction. If you want a directional opinion, this number will not give you one.

Why the straddle price contains the answer

A straddle is a pair of options bought together: one call and one put, same underlying, same expiry, sharing a strike as close as possible to the current stock price. The two legs cancel out any view on direction. The call pays off if the stock rises well above the strike, the put if it falls well below. What the buyer is really buying is movement.

That is what makes the price informative. The buyer profits only if the stock travels far enough in either direction to cover the combined premium; the seller profits if it stays put. The price both sides settle on is therefore the market-clearing estimate of how far the stock will travel by expiry, quoted in dollars.

Converting dollars into a percentage is then trivial:

For the two input prices we use the mid of the bid and the ask whenever both quotes are present, and fall back to the last traded price when they are not. The underlying market data comes from Yahoo Finance.

A worked example

The numbers below are illustrative, chosen for clarity rather than drawn from any real security.

Suppose a stock trades at $100 and reports earnings next week. At the expiry falling just after the report, the nearest strike is $100, where the call is quoted at a mid price of $5.50 and the put at $4.50. The straddle costs $5.50 + $4.50 = $10.00, and as a percentage of the share price that is 10.00 ÷ 100 = 10%.

The interpretation: the options market is pricing a move of roughly $10 in either direction by that expiry, a range of about $90 to $110. That is not a prediction the stock will reach either edge, nor a hint about which edge is likelier. It describes the width of the distribution the market is paying for. The call and put are not priced identically here, which is normal and reflects skew and hedging demand rather than any directional view.

What the percentage actually represents

Precision matters here, because the straddle rule of thumb is often described with more confidence than it deserves.

Dividing the straddle price by the stock price is an approximation. Under the assumptions common to standard option-pricing models, the resulting percentage corresponds very roughly to a one-standard-deviation move over the remaining life of the option. Taken at face value, the stock would finish inside that range something like two times out of three, which also means finishing outside it roughly one time in three is ordinary rather than evidence the number was wrong.

There is a second imprecision. The implied move measures expected travel to expiry, not the overnight reaction to the release. When the expiry falls several days after the report, those options also cover the ordinary market noise of the extra days, so the figure tends to overstate the earnings-specific move, and overstates it more as the gap widens.

Implementation details and their consequences

Every choice below is defensible, and every one introduces some error. We would rather set them out than let the number look more exact than it is.

The expiry is the first one on or after earnings

Depending on when in the week the company reports and which expiries are listed, the chosen contract might expire the next day or nearly a week later. A longer gap means more non-earnings time priced into the straddle, and therefore a larger figure for reasons unrelated to the report. Two companies with identical expected reactions can show different implied moves purely because of the calendar.

Call and put strikes are chosen independently

For each leg we pick the strike with the smallest absolute difference from the current stock price, selected separately. When the share price sits near the midpoint between two listed strikes, the legs can land on different strikes, making the result a narrow strangle rather than a true straddle and slightly distorting the sum.

Falling back to the last traded price

When a bid or ask is missing, we use the contract's last traded price. On a thinly traded option that trade may have occurred hours earlier, when the stock was at a materially different level. This is the most significant accuracy risk in the calculation, and it concentrates where liquidity is thinnest.

Mid prices are estimates, not executable prices

Even when both quotes exist, the mid is a convention. Single-stock options routinely carry wide bid-ask spreads, and the price at which someone could actually buy the straddle sits closer to the ask.

The 21-day window

The figure is computed only when the next earnings date is between zero and twenty-one days away, which keeps the expiry close enough to the report to be meaningful. A company reporting in six weeks shows no implied move at all. Where it is computed, the percentage appears as an alert in the daily email digest and alongside each ticker in the weekly earnings calendar.

Volatility crush

This concept carries the most practical consequence of anything on the page, and it is the reason the implied move is so often misused.

Implied volatility rises into an earnings report because the outcome is genuinely uncertain, and sellers demand compensation for carrying that uncertainty. The moment the report lands, the uncertainty resolves and the elevated implied volatility collapses almost immediately across every option on the stock. Traders call this volatility crush.

The effect is counterintuitive: you can be right about the direction and still lose money. An option bought into earnings carries a premium inflated by pre-announcement uncertainty, and after the release that inflation is gone. To profit, the stock must move by more than the implied move, not merely in the anticipated direction, because it has to overcome both the premium paid and the post-event decline in implied volatility.

This is why we present the figure as a risk-framing tool rather than a signal. It tells you how much turbulence the market is already braced for. It does not tell you that turbulence is mispriced.

How to use it

Used within its limits, the implied move is genuinely useful context in the days before a report:

• Set expectations before the report, not after. Knowing a name carries a 12% implied move makes a 10% drop the next morning an ordinary outcome rather than a shock.
• Use it as an input to position sizing. A plausible short-term swing you have already considered is easier to sit through than one you have not.
• Compare it against the stock's own history. Some companies routinely move less than the options market prices, others more. The figure is most informative set against how that stock has reacted to past reports.
• Treat an unusually large implied move as a warning, not an opportunity. A number well above the ticker's normal range signals unusual uncertainty, already reflected in what the options cost.
• Remember it says nothing about direction. No amount of context turns a symmetric magnitude estimate into a view on whether the news will be good.

For the full inventory of where each figure on the site comes from, see our data and methodology page. Definitions of the terms above are in the glossary.

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