Credit Events Simultaneously Lift Skew and Term Structure

A credit event, such as a bankruptcy, credit downgrade, or default risk, injects sudden uncertainty into the market. In equities or indexes, this uncertainty manifests through increased demand for downside protection. Put options, especially far OTM puts, see a surge in buying interest. As a result:

  • Skew steepens: Out-of-the-money (OTM) puts increase in implied volatility faster than at-the-money (ATM) or call options, reflecting demand for downside protection.
  • Term structure steepens: Implied vol for longer-dated options rises as the perceived duration of risk increases.

The reason skew and term structure are jointly affected is due to the nature of credit events: they’re not seen as temporary disruptions, but systemic threats with longer-term implications. Markets price in a risk premium over extended timeframes, and the tail risk associated with severe downside events lifts the value of long-dated puts.

In short, a credit event alters the entire volatility surface, not just one dimension. Skew becomes more negative (steeper), and the term structure of implied volatility shifts upward as markets digest the full scope of long-term uncertainty.

Sticky Implied Volatility for Low Strikes and Long Maturities

Another reason skew and term structure are linked is implied volatility stickiness, especially in low-delta (OTM) strikes and long-dated expiries. Stickiness means that once high vol is priced into these parts of the surface, it tends to persist, even if near-term realized volatility falls.

Why is this important?

  • OTM puts (low strike options) are heavily used for tail-risk hedging and stress scenarios. Demand for these instruments tends to remain structurally elevated, especially in a post-GFC or pandemic world.
  • Long-dated options are commonly used by institutions to hedge portfolios or manage risk across multi-quarter timeframes. Their implied volatility reflects strategic hedging flows, not just tactical ones.

This persistent demand holds up both skew (through elevated vol on low strikes) and term structure (through high vol for long expiries). The sticky behavior ensures that even in calm markets, the back end of the volatility surface doesn’t collapse.

As such, the elevated implied volatility on both axes, strike and time, reinforces their correlation. A change in one dimension often leads to re-pricing in the other due to the interconnected nature of market expectations.

Sticky Implied Correlation for Low Strikes and Long Maturities (Index-Specific)

This third dynamic only applies to index options, not single names. It stems from the behavior of implied correlation at the index level, particularly for tail events and long-term risk.

Here’s how it works:

  • In times of market stress or long-term uncertainty, the correlation between constituents in an index tends to rise. That is, individual stocks move together.
  • This increased correlation pushes up index-level implied volatility more than it pushes up single-name implied vol. As a result, skew and term structure rise in index products like SPX or NDX.

This phenomenon is especially sticky for long-dated, deep OTM puts on index options. These puts are commonly used by institutional investors as systemic risk hedges. Since systemic risk (e.g., a global recession) causes stocks to move in tandem, implied correlation at low strikes and long expiries remains elevated.

From a modeling perspective, this behavior means that both skew and term structure must adjust to reflect the impact of rising correlation on downside scenarios. It’s another way the surface reconfigures itself due to macro stress, showing again why these two measures of implied volatility tend to move together.

Putting It Together: Skew, Term Structure, and the Volatility Surface

Ultimately, skew and term structure are just two slices of the same three-dimensional volatility surface. They move together because they are influenced by the same structural and behavioral forces:

  • Macro events inject stress across strikes and maturities simultaneously.
  • Investor demand for hedges concentrates in low strikes and long tenors.
  • Market structure and modeling assumptions, such as implied correlation and sticky vol surfaces, preserve these relationships.

For traders and risk managers, understanding this correlation helps in:

  • Pricing complex option structures (e.g., risk reversals, butterflies, calendars)
  • Hedging volatility exposures in both strike and time dimensions
  • Anticipating how vol surfaces might evolve in response to macro catalysts

For example, during periods of complacency, traders might notice skew flattening and term structure compressing, a sign that demand for downside protection is drying up. Conversely, in pre-FOMC or geopolitical uncertainty, a simultaneous steepening of skew and curve often points to heightened demand for protection.

Conclusion: A Unified View of Volatility Dynamics

Skew and term structure are not isolated features of the options market. They are interdependent expressions of how traders price risk across strike and time. Whether due to systemic events, persistent demand for tail protection, or sticky implied correlations in indices, the tendency for skew and term structure to rise or fall together reflects deeper truths about market psychology and structure.

Understanding these relationships allows traders to interpret volatility signals with more nuance, and to construct better strategies that account for how the entire vol surface might shift in response to events. In a world where options trading is increasingly quantitative and flow-driven, mastering these interactions is not just useful, it’s essential.