Trading Strategies
Trading Earnings Season: Gaps, IV Crush and the Drift
An earnings date turns an ordinary position into a binary event that your stop order cannot sit inside. Here is what the market charges for it.
The report lands at 4:05pm. You are not at your desk, and it would not help if you were. Between the close and the next open the stock reprices in a single auction print, and the stop order sitting in your account has no way to work inside a jump that carries the price from the last trade of one session to the first of the next. Every decision that mattered was made before the close.
Check the date first, every time
Earnings cluster in the weeks after each quarter ends. Most large companies report before the open or after the close. Confirmed dates come from the company. Everything else on a calendar is an estimate. That includes the one your platform shows you.
The routine takes seconds. Before opening a position, check the report date. Before carrying anything into a weekend, check it again. A position you sized as a swing trade turns into an earnings bet the instant a report lands inside the holding period, which is the same hazard described from the other side in swing trading explained.
What is actually in the release, and why a beat can still be sold hard, is in how to read an earnings report. Guidance moves stocks more often than the quarter being reported does.
The option market has already priced the move
You do not have to guess how big the move will be. The number is on the screen.
Take the at the money call and the at the money put. Both expire just after the event. Add the premiums. A $100 stock with a $4.20 call and a $3.80 put gives $4.20 + $3.80 = $8.00, which is $8.00 / $100 = 8%. That is the price of a roughly 8 percent move in either direction.
That figure is the hurdle for anyone buying options into the print: the stock has to travel more than 8 percent for a long straddle to pay, and a 5 percent move, which would be a very large day for most stocks, still loses.
| Actual move | Straddle value at expiry | Paid | Result |
|---|---|---|---|
| Unchanged at $100 | $0 | $8.00 | minus $8.00 |
| $105, a 5% move | $5.00 | $8.00 | minus $3.00 |
| $108, an 8% move | $8.00 | $8.00 | $0 |
| $115, a 15% move | $15.00 | $8.00 | plus $7.00 |
Why the premium collapses the next morning
Implied volatility rises into a report because a large move is possible. The morning after, the uncertainty is resolved. Implied volatility falls sharply, deflating every option on the name at once.
A call bought at 70 percent implied volatility the afternoon before and marked at 35 percent the next morning has lost a large part of its extrinsic value on the volatility change alone. A trader who called the direction correctly, on a stock that moved less than implied, closes for a loss. He cannot work out why. The mechanics are in implied volatility explained, the terminology in options trading for beginners.
What a gap does to a correctly sized position
You hold 100 shares bought at $50 on a $20,000 account, stop at $48, and the planned loss is 100 x $2 = $200, which is your 1 percent. The company guides lower after the close. The stock opens at $41, your stop triggers into the opening print and fills near $41, and the loss is 100 x $9 = $900. That is 4.5 times the intended risk and 4.5 percent of the account. The position obeyed every rule you have except the one about events.
The fixes are arithmetic. Close before the print, which costs you the move and removes the exposure. Or size to the implied move, so the number the option market is quoting becomes the loss you are willing to take. With an 8 percent implied move on a $50 stock, that is $4 a share against you. A $200 budget then supports $200 / $4 = 50 shares, half the position.
| Approach | Position through the event | Loss if the implied move goes against you |
|---|---|---|
| Full size, normal stop | 100 shares | Uncapped, $900 in the example above |
| Sized to the implied move | 50 shares | About $200 |
| Flat into the print | 0 shares | None, and no participation |
The morning after gives you a level
Once the numbers are public you get something no pre announcement trade ever offers: a reference price with real order flow around it, so the opening range, the gap edge and the previous close all become levels other people are trading against.
Two trades dominate the session. Gap and go buys a stock that opened above the prior range, held its opening range and is extending on heavy volume, with the stop back inside the gap, on the reasoning that the repricing was not enough and buyers are still working. The fade sells into a gap that failed to hold its opening range and has started filling toward the previous close, on the reasoning that the first reaction overshot.
Both are day trades. Four or more of them inside five business days in a margin account puts you under FINRA’s pattern day trader rule and its $25,000 equity requirement, and the intraday costs are laid out in day trading explained.
The drift
Post earnings announcement drift is the tendency for a stock that surprised strongly to keep moving that way over the following weeks. Academic research has documented it for decades. It remains one of the more persistent anomalies in the literature.
Handle it carefully for three reasons. It is an average across many events. Your particular case can reverse on day two. It is well known now, which historically shrinks an effect. And capturing it means weeks of exposure to everything else that can happen to a stock, including the next report.
If you trade it, the rule follows the size of the surprise. The direction of the day is noise. Rank the largest surprises and the largest gaps in the stock screener, then apply a normal entry and a normal stop.
Where earnings trading goes wrong
Sizing that ignores the event, which is the $900 above.
Stacking reports. Three positions each risking 1 percent, all reporting inside four sessions, is a single 3 percent bet that the season treats you kindly, and the losses land together. A few weeks like that build a drawdown quickly, and recovering from 30 percent down costs 42.9 percent on the way up, since 0.70 x 1.429 = 1.00. The drawdown recovery calculator shows how fast the requirement accelerates.
And trading the headline number in the first seconds after the release, when the spread is at its widest of the day and the guidance that actually matters is three paragraphs further down the page. Whoever filled you there knew both of those things.
The sizing framework, including heat across correlated positions, is in risk management for traders. The groundwork sits in how to start trading stocks.
Frequently asked questions
What is IV crush?
Implied volatility is the volatility the option market has priced into premiums. It runs high before a report because a large move is possible, and the moment the numbers are public that uncertainty is gone, so implied volatility drops sharply. Option buyers can be right about the direction and still lose, because they paid for uncertainty that has just been removed.
How do you work out the market's expected earnings move?
Take the at the money call and put expiring just after the event and add their prices. A $100 stock with a $4.20 call and a $3.80 put gives a straddle of $8.00, implying a move of roughly 8 percent in either direction by expiry. It estimates size and says nothing about direction, and a smaller move than that is what hurts option buyers.
Should you hold a stock through earnings?
Only if the trade is specifically about the event and sized for it. A stop does not protect you across an earnings gap, because the price jumps in the opening auction and your stop becomes a market order at whatever is available. A position sized to risk 1 percent can lose four or five times that overnight.
What is post earnings announcement drift?
The documented tendency for a stock that surprised strongly in one direction to keep drifting that way for weeks afterwards. Academic research has recorded the effect for decades. It is better known now and harder to capture, it is an average across many events, and transaction costs consume a meaningful share of what is left.
Is it better to trade before or after the announcement?
Before the print you are exposed to an outcome nobody can know, so size has to reflect that. After the print the uncertainty is resolved, the premium has deflated and the stock is repricing on information anyone can read. Most traders with a defined process find the following session gives them a level to work with and a stop that means something.
How do you find which companies report this week?
Every broker publishes an earnings calendar and screeners let you filter by report date. The habit that matters is checking the date on every open position before the close, because the expensive version of this mistake is finding out about a report after it has already moved your stock.