IV Crush in Options: Why Premiums Fall the Morning After Results

IV crush in options is the reason so many traders get the results call right and still lose money. You buy a call the evening before a company reports, the numbers come in decent, the stock opens 2% higher, and your call is somehow worth less than what you paid. Nothing is broken. The option was priced for a big move, the big move didn’t come, and the extra premium that the market had built in for the uncertainty simply drained out overnight.

This piece walks through why that happens, how to spot it before you place the trade, and what the numbers look like on a hypothetical results-week setup. The stock, prices and volatility levels in our examples are made up. The ideas behind them come from Investopedia’s guide to implied volatility and Zerodha Varsity’s chapters on vega and volatility applications, and every premium in the tables was worked out with the standard Black-Scholes formula.

What IV crush in options actually means

Start with implied volatility, or IV. It’s the market’s estimate of how much a stock is likely to move over a period, written as an annualised percentage. Note what it doesn’t tell you: direction. Investopedia’s explanation is blunt on this. IV is about the size of the expected swing, up or down, not whether the price will rise or fall.

You can’t look up IV the way you look up a share price. It is backed out of the option’s own premium. Take the market price of the option, feed in the stock price, strike, time to expiry and interest rate into a pricing model such as Black-Scholes, and solve for the one volatility number that makes the model match the price. Investopedia describes it as the only input in the model that isn’t directly observable in the market.

So when traders rush to buy options ahead of an event, they push premiums up, and the IV you calculate from those premiums goes up with them. Investopedia notes that IV often climbs before events such as earnings announcements because traders expect a large move. Once the announcement is out, the uncertainty is gone. IV often falls sharply, even when the stock moves exactly as expected. That sudden drop is the IV crush, and it can pull an option’s value down despite a move in your favour.

Before results you aren’t just betting on direction. You’re paying for uncertainty, and uncertainty has a shelf life of one announcement.

Why option writers charge more before an event

Zerodha Varsity’s vega chapter gives a neat way to see this from the seller’s side. Picture an out-of-the-money call trading at Rs 20 with ten days left. Would you write it? Maybe. Now add that corporate results or election results fall inside those ten days. Most writers would want Rs 30 or Rs 40 to take the same risk, because a sharp move could push that option into the money. Fear can be overcome, but only for a price, and that price is a fatter premium on both calls and puts.

Varsity’s own author goes a step further in the volatility applications chapter. He writes that he avoids writing options around important events such as monetary policy and corporate announcements, since markets can react sharply and you can get caught on the wrong side. That’s an experienced seller telling you the pre-event premium isn’t free money either.

Buyers, meanwhile, are paying that inflated price. If the move turns out smaller than the premium assumed, the buyer is the one left holding an option that deflates the next morning.

Vega: the Greek that measures the damage

The Greek that links IV to premium is vega. Varsity defines it as the change in an option’s premium for every one percentage point change in volatility. Because options gain value as volatility rises, vega is positive for both calls and puts. Varsity’s example is simple: an option with a vega of 0.15 gains or loses 0.15 in theoretical value for each 1% change in volatility. If you want the full treatment, our explainer on vega in options goes deeper.

Here’s why that matters for results trades. If IV drops by 20 points overnight, a vega of 0.8 knocks roughly Rs 16 off the premium before the stock has moved at all. That’s an approximation, since vega itself changes as IV and time change, but it gives you the right order of magnitude.

Varsity also points out that a change in volatility moves premiums most when there are more days left to expiry. With only a few days to go, the same jump in volatility lifts premiums by much less. Keep that in mind; it comes back in our second example.

Reading the expected move before results

Since IV is annualised, you need to scale it down to the period you care about. Volatility scales with the square root of time. Investopedia’s example takes a 20% annual IV and divides it by the square root of 12 to get a one-month figure, which works out to about 5.77%. The same logic works for days: multiply annual IV by the square root of (days left divided by 365).

One standard deviation covers roughly 68% of outcomes, and two cover about 95%, as both Investopedia and Varsity explain. So a one-standard-deviation move is the range the market thinks the stock will stay inside about two-thirds of the time.

Let’s put numbers on it. Our hypothetical stock, call it ABC Ltd, trades at Rs 1,500. Results are due after the close, and it’s expiry week, so the near-month at-the-money options have 7 days left. IV on those options has run up to 48%.

A quicker shortcut traders use is the at-the-money straddle. Add the call and put premiums at the strike nearest the current price, and divide by the stock price. In our example, the 1,500 call is worth about Rs 40.69 and the 1,500 put about Rs 38.82 (Black-Scholes, 48% IV, 6.5% assumed interest rate). Together that’s Rs 79.51, or roughly 5.3% of the stock price. That’s the rough size of move the option market is paying for.

If you can’t make a case that the stock will move more than that, buying options into the event is a bet against the odds already priced in.

Worked example 1: right direction, wrong trade

You buy the 1,500 call at Rs 40.69, expecting good numbers. Results are fine, the stock opens 2% higher at Rs 1,530, and IV collapses from 48% to 26% because the uncertainty is gone. One day of time has also passed, so there are 6 days to expiry.

Look at the second row. You were right on direction, the stock went up 2%, and you’re still slightly down. In this setup the call only breaks even at about Rs 1,531.50, a 2.1% rise. A 3% move makes money, but less than half of what it would have made if IV had stayed put. The gap between the last two rows, about Rs 13.67 per share, is the crush.

And if the stock doesn’t move at all? The call loses roughly half its value overnight, from Rs 40.69 to Rs 20.75. Nothing about the company changed. Only the uncertainty did.

Worked example 2: the straddle buyer’s problem

A lot of traders think the fix is a straddle. Buy both the call and the put, and you win whichever way it moves, right? Not quite. You win only if the move beats what you paid for both. Our straddle costs Rs 79.51. Here’s how it looks the morning after, with IV at 26% and 6 days left:

The straddle needs something close to a 5.3% move just to get its money back, which is exactly the move the premium had priced in. Anything smaller and IV crush eats you. That’s not a flaw in the straddle. It’s what a fairly priced option looks like. Our guide to the long straddle strategy covers when it can still make sense.

A straddle doesn’t pay you for being right that something will happen. It pays you only if what happens is bigger than what everyone already expected.

Now flip it around. The trader who sold that straddle at Rs 79.51 and bought it back at Rs 39.89 on a flat open pockets Rs 39.62 per share. That’s the trade IV sellers are chasing. But look at the row where the stock goes to Rs 1,590. The seller is now losing, and on a bigger surprise the loss keeps growing with no ceiling on the call side. This is the risk Varsity’s author steps aside from by not writing options into events.

Worked example 3: longer expiry, slower crush

Varsity’s point about time to expiry shows up here. Suppose instead of the 7-day option you bought a 30-day at-the-money call at 40% IV. It costs about Rs 72.47. After results, the stock is flat, a day passes, and IV drops to 32%. The call is now worth about Rs 57.77, a fall of roughly 20%.

Compare that with the 7-day option in example 1, which lost about 49% in the same flat scenario. Part of that difference is the size of the IV drop we assumed, and part is the faster time decay of an option in its last week, which our piece on theta decay explains. Either way, the longer-dated option has more time for the stock to move after the event, so its value doesn’t rest entirely on the overnight reaction.

The catch is that longer-dated options have higher vega, so if you buy them when IV is already stretched, you are exposed to the crush for longer too. There’s no free lunch, just a different mix of risks.

How traders handle IV crush

None of this means you should never trade options around results. It means you should know which side of the volatility trade you’re on. A few habits help:

• Check IV before you check the chart. NSE publishes implied volatility for each strike in the option chain, as Varsity points out. If IV on the stock’s near-month options is far above its usual level going into results, you’re buying expensive insurance.
• Do the straddle maths. Add the at-the-money call and put, divide by the price, and ask yourself honestly whether the stock is likely to move more than that.
• Prefer spreads to naked buying. A call spread, where you buy one call and sell a higher strike, offsets part of the vega you’re exposed to. You give up some upside, but the crush hurts both legs and partly cancels out.
• If you sell premium, define your risk. Collecting inflated premium can work, but an uncapped short straddle into results is how small, steady gains get wiped out by one big gap. Iron condors or hedged structures limit the worst case.
• Exit plans matter more than entry. Decide before results what you’ll do at the open, whether that’s exiting at once or holding with a stop. Our risk management guide covers position sizing for exactly this kind of binary event.

One more thing: India VIX works on the same principle at the index level. As Varsity explains, drawing on NSE’s whitepaper, NSE computes India VIX from the order book of near-month and next-month Nifty options, and it reflects the market’s expectation of volatility over the next 30 calendar days, shown as an annualised percentage. Big scheduled events such as an RBI policy decision or a Budget can lift index option premiums in the same way, and the same crush can follow once the event is out.

Quick recap before your next results trade

IV crush in options is the hangover after an event. Premiums swell beforehand because nobody knows what’s coming. The announcement removes that uncertainty, IV drops, and vega converts the drop into a lower premium, often overnight. If you’re buying, you need a move bigger than the one already priced in. If you’re selling, you need protection against the day the move is much bigger than anyone priced in. Work out the expected move first, then decide whether the trade still makes sense.

Disclaimer: This article is for information and education only and is not investment advice or a recommendation to buy or sell any security or derivative. ABC Ltd, its prices, the implied volatility levels and the interest rate in the examples are hypothetical and are used only to show how option pricing behaves; premiums were calculated with the Black-Scholes model and real market prices will differ. Options trading carries a high risk of loss. Please consult a SEBI-registered investment adviser before trading.