Volatility term structure
Volatility term structure describes how implied volatility changes across different expiration dates for the same underlying asset. An ATM option expiring in 7 days and an ATM option expiring in 6 months on the same stock will almost never carry the same IV. The pattern of those differences, plotted across time, is the term structure of volatility, and reading it correctly changes how you select expirations, structure spreads, and time your entries.
What normal term structure looks like
In a calm market, the volatility term structure is upward sloping: longer-dated options carry higher IV than shorter-dated ones. This is intuitive. More time means more uncertainty, and the market prices that by charging more for options that expire further out.
A typical normal term structure for SPY might look like:
| Expiration | Approx. IV |
|---|---|
| 7 days | 13% |
| 30 days | 15% |
| 60 days | 16% |
| 90 days | 17% |
| 180 days | 18% |
Each additional month of time adds a small, diminishing amount of implied volatility.
Inverted term structure, when short-term IV spikes
When markets are stressed (a sharp selloff, a geopolitical shock, an earnings event in the near term) the term structure flips. Short-dated options suddenly carry higher IV than longer-dated ones. This is called an inverted or backwardated term structure.
Why it happens: Demand for immediate protection spikes. Traders rush to buy near-term puts, bidding up short-dated IV dramatically. Longer-dated options don't reprice as aggressively because the fear is about the near-term event, not indefinite future uncertainty.
What it looks like:
| Expiration | Approx. IV (stressed market) |
|---|---|
| 7 days | 42% |
| 30 days | 35% |
| 60 days | 28% |
| 90 days | 24% |
| 180 days | 21% |
The front month is now far more expensive than longer expirations, a clear inversion.
Why term structure matters for traders
1. Expiration selection for premium sellers
In a normal (upward sloping) term structure, selling 30 to 45 DTE options gives you the best balance of premium and time. The front week is too cheap relative to the gamma risk. Going out 6 months collects more premium but ties up capital and has lower theta per day.
In an inverted term structure, short-dated options are disproportionately expensive. This is one of the best environments for selling near-term premium, you're collecting elevated IV that almost certainly reverts once the near-term catalyst passes.
2. Calendar spreads live and die by term structure
A calendar spread sells a near-term option and buys a longer-dated option at the same strike. The entire premise is that near-term IV is elevated relative to longer-dated IV. You sell the expensive front month, own the cheaper back month.
- Normal term structure: Calendar spreads work but the edge is modest, near-term and back-month IV aren't far apart.
- Inverted term structure: Calendar spreads are at their best, you're selling highly elevated near-term IV against much cheaper longer-dated IV. The differential is wide and likely to compress as the catalyst passes.
This is why many experienced traders specifically look for inverted term structure as their signal to enter calendar spreads, particularly before earnings, where front-month IV is dramatically elevated relative to the next expiration.
3. Rolling decisions
When you hold a short options position and consider rolling it forward, term structure tells you whether you'll collect a meaningful credit for the extra time. In a normal structure, rolling out 30 days typically generates a worthwhile credit. In a flat or inverted structure, the roll may generate little or no additional premium, sometimes not worth the transaction cost.
Reading the VIX term structure
The most widely tracked volatility term structure is the VIX futures curve, the spread between near-term VIX futures and longer-dated ones. It's a real-time indicator of market stress and sentiment.
- Contango (normal): Longer-dated VIX futures are priced higher than near-term ones. The market is calm. This is the default state roughly 70 to 80% of the time.
- Backwardation (inverted): Near-term VIX futures are priced higher than longer-dated ones. The market is under stress. Near-term fear is elevated relative to the longer-term outlook.
The VIX term structure is why products like VXX (which hold front-month VIX futures) suffer from persistent decay in contango environments. They're constantly rolling from cheaper near-term contracts into more expensive ones, creating a structural headwind.
Term structure and earnings
Earnings create the most dramatic and predictable term structure distortions in individual stocks. The expiration immediately after the announcement carries far higher IV than subsequent expirations, sometimes 2 to 3 times the IV of the next month out.
This steep local inversion is the opportunity for earnings calendar spreads: sell the overpriced front-expiry, buy the much cheaper back-expiry at the same strike. If the stock stays near the strike after earnings and IV crushes back to the back-month level, the trade profits from the differential collapsing.
Example: NFLX has earnings in 4 days. The weekly expiry capturing earnings has IV of 85%. The following monthly expiry has IV of 32%. The term structure is severely inverted at the front. A calendar spread here sells expensive near-term IV (85%) and owns cheap longer-term IV (32%), a 53-point differential that almost certainly compresses to near zero after the announcement.
Practical checklist for using term structure
- Before selling premium: Is near-term IV elevated relative to back months? If yes, selling the front expiry is more attractive than usual.
- Before buying a calendar: Is the term structure inverted or steeply normal? Inverted equals best setup for calendars.
- Before rolling: Is there meaningful premium to collect by rolling forward? Flat structure means rolling may not be worth it.
- After a VIX spike: Check whether the term structure has inverted, near-term options may be significantly overpriced relative to their normal relationship with longer-dated ones.
Related terms: Implied volatility, IV rank, calendar spread, VIX, IV crush, vega, contango
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