Chapter 4 of 9

Implied volatility, skew and event risk

Distinguish realized variability from the volatility embedded in an option premium, including event-related repricing.

3 min read · Original educational chapter

In this chapter

Historical and implied volatility answer different questions
There is a surface, not one number
An event can be expensive before it happens
Decision lab: An event outcome and an option result can disagree
Worked example
Common mistakes
Check your understanding

Historical and implied volatility answer different questions #

Realized volatility summarizes past price variation under a chosen measurement method and window. Implied volatility is an input inferred from a pricing model and a market premium. It is model-dependent and need not equal the variability subsequently realized.

A higher implied-volatility figure generally corresponds to a higher option value when other model inputs are fixed. It does not provide the direction of the next underlying move. Two positions with similar directional exposure can differ greatly in their volatility exposure.

There is a surface, not one number #

Implied volatility can vary across strikes and expiries. A skew describes variation across strikes; a term structure describes variation across maturities. The surface can reflect asymmetric risk, supply–demand conditions, expected events and market frictions.

Comparisons should match instrument conventions, time to expiry and data quality. An illiquid last traded premium can imply a strange value that is not available at the bid or ask. Model inversion does not validate the quality of the underlying quote.

An event can be expensive before it happens #

Before a scheduled announcement, premiums may embed uncertainty about its outcome. Once the event passes, implied volatility can fall even if the underlying moves. An option buyer therefore needs more than a correct direction to cover the price paid for that uncertainty.

The expression volatility crush describes this repricing; it is not a guaranteed post-event trade. The realized move can be much larger than anticipated, particularly for an uncovered writer. Study both sides with stress cases rather than assuming events always resolve quietly.

Decision lab: An event outcome and an option result can disagree #

An option can lose after the predicted directional move if the paid premium required a larger movement or implied volatility falls. “The news was bullish” does not reconcile the actual debit, strike, time and execution price.

Write a pre-event scenario table with direction, magnitude, time and implied-volatility assumptions varied separately. Identify the observation that would invalidate the thesis. Compare price-only reasoning with the full option exposure rather than treating a correct headline call as evidence of a profitable trade.

Hypothetical worked example

A favorable move and an unfavorable volatility change

A fictional option premium is 10 before an announcement. A local illustration attributes +2 to the underlying move, −3.5 to lower implied volatility and −0.2 to elapsed time, producing an approximate new premium of 8.3.

The example does not claim that these components can always be measured independently or added exactly. It explains why showing only the underlying chart leaves an incomplete account of option P&L.

The option writer’s potential gain from that outcome does not make the position safe: an unexpectedly large move could instead create a substantial loss and higher funding needs.

Common mistakes

Treating implied volatility as a forecast of price direction.
Using a stale last trade to claim that an option is mispriced.

Check your understanding

Can implied volatility fall after an event while the underlying rises?

Make this chapter useful

Can you defend the reasoning?

Before moving on, answer the self-check in your own words and write why each alternative fails. Use the worked example to test that explanation. Then apply it in the module research task; keep the assumptions and the evidence that could change your answer.

Sources and further reading

Further-reading references from the curriculum source list. Contract sizes, expiry calendars, settlement references, margin parameters and tax treatment can change; verify the current operative documents for the actual product. Worked figures are illustrative, not current quotes.

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General financial education. No securities recommendation, assured outcome or personal advice. Read the risk disclosures.