Options Skew

Learning objectives

• Understand implied-volatility skew and smile rather than comparing option prices directly.
• Calculate and interpret a 25-delta risk-reversal style measure while stating the sign convention.
• Separate skew from absolute volatility level and term structure.

Mechanics and institutional interpretation

Options with different strikes have different intrinsic value and delta, so raw premiums are poor tools for comparing tail pricing. Implied volatility converts price into a volatility parameter under an option-pricing model, allowing analysts to compare puts and calls on a more consistent basis.

One common crypto measure compares the implied volatility of a 25-delta put with a 25-delta call. Some dashboards define skew as put IV minus call IV; others use call IV minus put IV. Therefore a statement such as '25-delta skew is +8' is incomplete unless the convention is stated.

A stronger downside put volatility under the put-minus-call convention indicates more expensive downside protection relative to upside calls. But skew can move because puts are bid, calls are offered, spot moves through strikes, dealer inventory changes or the overall vol surface reprices.

Skew should be evaluated across expiry. One-week downside protection can become extremely expensive around an event while three-month skew remains stable. The smile shape can also be nonlinear, so one 25-delta statistic does not describe the entire surface.

Advanced implementation considerations

Institutional option analysis also needs liquidity checks. A quoted implied volatility at 25 delta can be unstable if the market is wide or the strike has little executable size. Surface construction methods interpolate between strikes, so apparent smoothness can exceed the quality of the raw market. Analysts should retain bid/ask implied volatilities and size, not only a single mid-derived skew statistic, and should compare the same delta convention across dates.

Measurement framework

Worked example

Common mistakes and practical workflow

• Quoting skew without specifying put-minus-call or call-minus-put.
• Comparing raw option premiums across strikes instead of implied volatility or another normalised metric.
• Treating skew as a pure forecast of direction.
• Ignoring expiry, spot movement and liquidity when comparing skew over time.

Practical workflow

1. Define the exact instrument, venue, benchmark and decision horizon.
2. Normalise units and document the calculation or execution convention.
3. Cross-check the result with independent market or infrastructure data.
4. Model fees, financing, liquidity, counterparty and operational constraints.
5. Record the conclusion, risk limit and invalidation condition for post-trade review.

Knowledge checkpoint

1. Define Options Skew in your own words and state the exact market or execution problem it addresses.
2. Which convention, venue rule or model assumption could reverse your interpretation?
3. What data would you cross-check before committing capital or changing execution?
4. How would the conclusion change under a realistic stress scenario?

FAQs

Summary

Options skew compares implied volatility across strikes or deltas. In crypto it is commonly used to examine how the market prices downside versus upside tail risk, but sign conventions vary across providers. The professional standard is to define the mechanism precisely, normalise the data, separate observation from inference and connect the result to an explicit execution or risk decision.