Vol Crush - Why Options Lose Value After Earnings

By EC Assets Research Team, Volatility Research · Published 12 August 2026 · Updated 12 August 2026

Vol Crush: A vol crush is the abrupt collapse in implied volatility that follows a scheduled event once its outcome is known. Event variance drops out of the option price, the front expiry reverts to its diffusive baseline, and a long option can be right about direction, wrong about magnitude, and still lose.

What a Vol Crush Is

A vol crush is the abrupt collapse in implied volatility that follows a scheduled event once the outcome is known. Earnings are the common case; drug trial results, court rulings, elections and central bank decisions behave the same way. The move is not a reaction to the news. It is the removal of a risk premium the option no longer needs to carry, and it happens on a timetable that everyone can see in advance.

Why Implied Volatility Rises First

Variance is additive over time. The variance an option must price is the ordinary day-to-day diffusion plus, when an event falls inside its life, the variance of the event jump itself:

σ²_total × T = σ²_diffusive × T + σ²_event

For a short-dated option T is small while the event jump is not, so the event term dominates and the quoted implied volatility is pushed sharply higher. This is why the term structure inverts into earnings: the front expiry, which must carry the entire jump, prints a higher implied volatility than expiries months out that spread the same jump across far more time.

The inversion builds gradually. Weeks out, the event sits inside several expiries and its contribution to each is modest. As the front expiry shortens, the same fixed jump variance is divided by an ever smaller T, and the quoted number climbs even though nothing new has been learned about the company.

The Collapse

The moment the announcement lands, σ²_event goes to zero. The front expiry no longer prices any jump and reverts to its diffusive baseline, often falling by a third or more on the opening print. The term structure flips back to its usual upward slope within minutes.

A long option holder therefore faces a race between two effects: the position gains from whatever the stock actually did and loses, through vega, from the implied volatility that just vanished. Whether the trade wins depends entirely on whether the stock moved further than the market had already charged for.

The Implied Move

The market's own estimate of the jump can be read directly off the at-the-money straddle:

Implied move ≈ ATM straddle premium / S

A stock at 100 with a 6.00 straddle into earnings carries an implied move of roughly 6 percent. A trader who buys that straddle and watches the stock gap 4 percent was directionally right that the stock would move, and still loses. The realised move fell short of the price paid, and the crush takes the remainder.

The same arithmetic can be run in reverse across two expiries to isolate the event itself. Comparing the total variance priced in an expiry that contains the announcement with one that does not leaves the jump variance as the difference, which is what desks mean when they speak of the event volatility as distinct from the headline implied volatility. It is the cleaner number, because it is not contaminated by how many ordinary trading days happen to sit in the contract.

Who Is on Each Side

Selling into the crush, through short straddles and strangles, iron condors, or calendar spreads that are long the back month against the inflated front, is the standard way to harvest event premium. It is the volatility risk premium in concentrated form, and it carries the same shape of risk: many small gains and an occasional loss that dwarfs them. A single earnings miss can move a stock three or four times its implied move, and a naked short-premium position has no cap on that outcome.

The calendar spread deserves separate mention because it isolates the effect rather than betting against the move. It sells the expiry carrying the jump and buys a later one that barely moves, so the position profits from the difference in how the two expiries reprice rather than from the stock staying still. It is a narrower bet with a correspondingly narrower payoff, and it still loses if the stock gaps far enough to overwhelm both legs.

Buying into the crush pays only when there is a genuine reason to believe the distribution is wider than the one priced. That is a high bar against a market that has watched the same company report for years and priced the event calendar accordingly.

Beyond Earnings

The pattern is general to any scheduled resolution of uncertainty. Regulatory decisions, litigation verdicts, index inclusion announcements, referendum and election dates, and scheduled central bank meetings all produce the same shape: a build in implied volatility into a known date, then an immediate collapse regardless of the outcome.

What differs is the size and the shape of the jump. A binary regulatory outcome produces a genuinely bimodal distribution, where the stock is worth either far more or far less and rarely anything in between. Standard option pricing assumes a continuous distribution instead, which is why implied volatility around true binary events tends to look extreme and why the straddle, built for a symmetric world, is a blunt instrument for trading them.

What It Is Not

A vol crush is not evidence that options were mispriced beforehand. Elevated pre-event implied volatility is the correct price for an option that must survive a jump of unknown size. The crush is the scheduled, entirely expected disappearance of a risk that has resolved, and it happens whether the news is good, bad or dull.

The systematic error is to read the pre-event level as a forecast of turbulence and the post-event collapse as the market having been wrong. Both readings are the same number doing its job: pricing a risk while it exists and dropping it the moment it does not.

[!key] Implied volatility rises into a scheduled event because the option must carry the event's jump variance, and collapses the moment that variance resolves. A long option therefore needs the underlying to move further than the implied move, not merely in the right direction.

[!warning] Selling event premium is not a reliable income strategy despite its high win rate. Most events resolve inside the implied move and the seller keeps the premium; occasionally a stock gaps several times that distance, and an uncovered short-premium position has no cap on that loss. The premium is compensation for that tail, not a free return.

Why It Matters for Institutional Investors

• Timing the cost of protection. A hedge bought immediately before a scheduled event pays for jump variance that will disappear on a known date. Where the protection is meant to cover a longer horizon, buying it after the event or in a later expiry avoids that premium entirely.
• Reading the surface correctly. An inverted term structure ahead of earnings is a normal mechanical feature, not a distress signal. Mistaking one for the other leads to badly timed risk reduction.
• Manager due diligence. Strategies that harvest event premium produce smooth returns and high win rates for long stretches. Their real risk is visible in the shape of the exposure rather than in the track record, which is why the tail has to be examined directly.

References

1. Patell, J. M., & Wolfson, M. A. (1979). Anticipated information releases reflected in call option prices. Journal of Accounting and Economics, 1(2).
2. Dubinsky, A., Johannes, M., Kaeck, A., & Seeger, N. J. (2019). Option pricing of earnings announcement risks. Review of Financial Studies, 32(2).
3. Natenberg, S. (2015). Option Volatility and Pricing (2nd ed.). McGraw-Hill.
4. Sinclair, E. (2013). Volatility Trading (2nd ed.). Wiley.
5. Bennett, C. (2014). Trading Volatility, Correlation, Term Structure and Skew.