XSP options analytics
XSP · Index
Data as of 6 November 2026 (end of day)
XSP options are pricing a 30-day at-the-money volatility of 18.5%, a move of about ±5.3% over the next month. That is higher than 85% of the 242 sessions in its trailing year.
Its 25-delta puts carry 8.50 volatility points more than the calls, which is further than on all but 5% of the past year.
The term structure is inverted: 90-day volatility is 5% below 30-day, which happens when the market prices something dated into the nearer expirations.
Current readings
- 30-day ATM implied volatilityⓘ
- 18.53%
- 25-delta risk reversalⓘ
- +8.50
- 25-delta butterflyⓘ
- +0.96
- Term structure slopeⓘ
- 0.946
Prices a move of about ±5.3% over 30 days, or ±1.2% on a typical day.
Higher than 85% of the past year.
Puts carry 8.50 volatility points more than calls the same distance from the money.
Higher than 95% of the past year.
The wings carry 0.96 volatility points more than at-the-money.
90-day volatility is 5% below 30-day.
Higher than 13% of the past year.
Where 30-day implied volatility sits
Against 242 prior sessions (one-year window)
- IV percentile, 1 year
- 85%
- IV rank, 1 year
- 29%
- IV percentile, 2 years
- 88%
- IV rank, 2 years
- 29%
Rank is the position between the lowest and highest readings in the window, so a single past extreme pins everything after it near one end. Percentile is the share of sessions below the current reading and is unaffected by how far that extreme reached. Both are withheld when the window holds fewer than 180 sessions.
Session detail
- Underlying close
- $737.69
- 30-day implied forward
- $741.18
- 60-day ATM IV
- 17.88%
- 90-day ATM IV
- 17.53%
- 180-day ATM IV
- 17.42%
- Expirations used
- 42
- Total open interest
- 850,043
- Put / call open interest
- 3.23
The forward is derived from put-call parity on the strikes nearest the money, not taken from the underlying close. It is what every moneyness and delta on this page is measured against.
30-day at-the-money implied volatility
Last 321 sessions
Show the underlying numbers (most recent 120)
| Session | 30-day ATM IV | 25-delta RR | Term slope | Close |
|---|---|---|---|---|
| 2026-11-06 | 18.53% | +8.50 | 0.946 | $737.69 |
| 2026-11-05 | 20.32% | +9.49 | 0.893 | $735.37 |
| 2026-11-04 | 13.10% | +4.42 | 1.054 | $768.86 |
| 2026-11-03 | 16.11% | +6.04 | 0.968 | $756.89 |
| 2026-11-02 | 16.44% | +6.56 | 0.964 | $754.14 |
| 2026-10-30 | 15.57% | +6.41 | 0.997 | $758.01 |
| 2026-10-29 | 12.71% | +4.65 | 1.093 | $772.04 |
| 2026-10-28 | 13.07% | +4.39 | 1.073 | $774.40 |
| 2026-10-27 | 13.55% | +4.61 | 1.052 | $772.26 |
| 2026-10-26 | 14.12% | +5.14 | 1.021 | $767.68 |
| 2026-10-23 | 14.92% | +5.94 | 1.001 | $762.37 |
| 2026-10-22 | 15.05% | +5.79 | 0.984 | $766.34 |
| 2026-10-21 | 13.08% | +4.05 | 1.042 | $775.72 |
| 2026-10-20 | 13.20% | +4.59 | 1.038 | $771.26 |
| 2026-10-19 | 13.37% | +5.26 | 1.036 | $769.07 |
| 2026-10-16 | 14.22% | +6.44 | 1.011 | $765.94 |
| 2026-10-15 | 12.45% | +4.23 | 1.072 | $774.41 |
| 2026-10-14 | 13.17% | +4.93 | 1.039 | $771.89 |
| 2026-10-13 | 12.07% | +3.72 | 1.094 | $780.55 |
| 2026-10-09 | 11.74% | +3.28 | 1.122 | $781.15 |
| 2026-10-08 | 12.47% | +3.84 | 1.079 | $776.54 |
| 2026-10-07 | 12.37% | +3.22 | 1.074 | $780.18 |
| 2026-10-06 | 12.22% | +2.82 | 1.087 | $781.89 |
| 2026-10-05 | 12.48% | +3.21 | 1.081 | $777.40 |
| 2026-10-02 | 12.20% | +3.49 | 1.108 | $772.27 |
| 2026-10-01 | 13.20% | +4.05 | 1.049 | $766.65 |
| 2026-09-30 | 13.18% | +3.88 | 1.041 | $765.15 |
| 2026-09-29 | 13.10% | +3.86 | 1.051 | $767.08 |
| 2026-09-28 | 12.68% | +3.76 | 1.079 | $768.37 |
| 2026-09-25 | 11.49% | +3.22 | 1.159 | $774.34 |
| 2026-09-24 | 12.20% | +3.60 | 1.123 | $770.41 |
| 2026-09-23 | 12.08% | +3.72 | 1.129 | $770.60 |
| 2026-09-22 | 11.33% | +2.71 | 1.179 | $776.46 |
| 2026-09-21 | 11.66% | +2.93 | 1.166 | $776.47 |
| 2026-09-18 | 11.58% | +3.92 | 1.173 | $765.05 |
| 2026-09-17 | 12.16% | +4.15 | 1.130 | $763.78 |
| 2026-09-16 | 14.08% | +5.49 | 1.040 | $755.18 |
| 2026-09-15 | 13.37% | +5.16 | 1.066 | $758.57 |
| 2026-09-14 | 13.03% | +5.05 | 1.081 | $762.00 |
| 2026-09-11 | 11.29% | +5.01 | 1.214 | $765.70 |
| 2026-09-10 | 14.00% | +5.46 | 1.048 | $759.17 |
| 2026-09-09 | 13.03% | +4.60 | 1.079 | $763.64 |
| 2026-09-08 | 12.42% | +4.20 | 1.105 | $767.35 |
| 2026-09-04 | 11.40% | +3.57 | 1.160 | $771.86 |
| 2026-09-03 | 11.37% | +3.27 | 1.147 | $774.77 |
| 2026-09-02 | 12.21% | +4.29 | 1.093 | $766.66 |
| 2026-09-01 | 12.77% | +5.03 | 1.068 | $763.15 |
| 2026-08-31 | 11.64% | +3.81 | 1.127 | $768.61 |
| 2026-08-28 | 11.18% | +3.40 | 1.187 | $771.18 |
| 2025-09-29 | 12.45% | +4.52 | 1.109 | $666.12 |
| 2025-09-26 | 11.90% | +4.24 | 1.145 | $664.37 |
| 2025-09-25 | 13.12% | +4.75 | 1.090 | $660.47 |
| 2025-09-24 | 12.90% | +4.46 | 1.100 | $663.80 |
| 2025-09-23 | 13.02% | +4.53 | 1.098 | $665.69 |
| 2025-09-22 | 12.37% | +4.28 | 1.124 | $669.38 |
| 2025-09-19 | 11.86% | +4.13 | 1.143 | $666.44 |
| 2025-09-18 | 11.94% | +4.13 | 1.130 | $663.20 |
| 2025-09-17 | 12.21% | +4.32 | 1.100 | $660.04 |
| 2025-09-16 | 12.57% | +4.41 | 1.088 | $660.68 |
| 2025-09-15 | 11.95% | +4.12 | 1.117 | $661.53 |
| 2025-09-12 | 11.06% | +3.90 | 1.176 | $658.43 |
| 2025-09-11 | 11.30% | +3.97 | 1.153 | $658.75 |
| 2025-09-10 | 11.66% | +4.67 | 1.128 | $653.20 |
| 2025-09-09 | 11.43% | +4.75 | 1.140 | $651.26 |
| 2025-09-08 | 11.48% | +4.77 | 1.139 | $649.52 |
| 2025-09-05 | 11.49% | +4.91 | 1.143 | $648.15 |
| 2025-09-04 | 11.52% | +4.84 | 1.130 | $650.21 |
| 2025-09-03 | 12.58% | +5.61 | 1.068 | $644.83 |
| 2025-09-02 | 12.78% | +5.85 | 1.069 | $641.55 |
| 2025-08-29 | 11.57% | +4.84 | 1.147 | $646.03 |
| 2025-08-28 | 10.91% | +4.05 | 1.169 | $650.19 |
| 2025-08-27 | 11.29% | +4.32 | 1.149 | $648.14 |
| 2025-08-26 | 11.06% | +4.23 | 1.161 | $646.59 |
| 2025-08-25 | 11.34% | +4.25 | 1.157 | $643.93 |
| 2025-08-22 | 10.95% | +3.97 | 1.168 | $646.69 |
| 2025-08-21 | 13.24% | +5.36 | 1.063 | $637.02 |
| 2025-08-20 | 12.47% | +4.91 | 1.097 | $639.58 |
| 2025-08-19 | 12.00% | +4.82 | 1.121 | $641.14 |
| 2025-08-18 | 11.46% | +4.22 | 1.147 | $644.92 |
| 2025-08-15 | 11.28% | +4.13 | 1.175 | $644.98 |
| 2025-08-14 | 11.08% | +3.94 | 1.172 | $646.85 |
| 2025-08-13 | 11.16% | +3.81 | 1.162 | $646.66 |
| 2025-08-12 | 11.33% | +3.88 | 1.146 | $644.58 |
| 2025-08-11 | 12.45% | +4.65 | 1.101 | $637.35 |
| 2025-08-08 | 11.48% | +4.22 | 1.142 | $638.94 |
| 2025-08-07 | 12.82% | +4.88 | 1.081 | $634.00 |
| 2025-08-06 | 13.01% | +5.15 | 1.072 | $634.51 |
| 2025-08-05 | 13.88% | +5.73 | 1.044 | $629.92 |
| 2025-08-04 | 12.90% | +5.45 | 1.078 | $632.99 |
| 2025-08-01 | 15.68% | +6.87 | 0.980 | $623.80 |
| 2025-07-31 | — | — | — | $633.94 |
| 2025-07-30 | — | — | — | $636.29 |
| 2025-07-29 | 12.35% | +4.83 | 1.090 | $637.09 |
| 2025-07-28 | 11.47% | +4.00 | 1.138 | $638.98 |
| 2025-07-25 | 11.48% | +3.74 | 1.138 | $638.86 |
| 2025-07-24 | 11.93% | +3.79 | 1.117 | $636.34 |
| 2025-07-23 | 12.17% | +3.86 | 1.106 | $635.89 |
| 2025-07-22 | 12.84% | +4.35 | 1.099 | $630.96 |
| 2025-07-21 | 12.95% | +4.31 | 1.093 | $630.56 |
| 2025-07-18 | 12.82% | +4.21 | 1.109 | $629.68 |
| 2025-07-17 | 13.06% | +4.23 | 1.086 | $629.74 |
| 2025-07-16 | 13.92% | +4.58 | 1.054 | $626.37 |
| 2025-07-15 | 14.24% | +4.57 | 1.043 | $624.38 |
| 2025-07-14 | 13.72% | +4.40 | 1.057 | $626.86 |
| 2025-07-11 | 13.10% | +4.02 | 1.086 | $625.98 |
| 2025-07-10 | 12.70% | +3.53 | 1.092 | $628.05 |
| 2025-07-09 | 13.13% | +3.66 | 1.073 | $626.33 |
| 2025-07-08 | 13.74% | +4.25 | 1.058 | $622.55 |
| 2025-07-07 | 14.64% | +4.63 | 1.029 | $623.00 |
| 2025-07-03 | — | — | — | $627.94 |
| 2025-07-02 | 13.58% | +4.19 | 1.049 | $622.74 |
| 2025-07-01 | 13.54% | +4.21 | 1.062 | $619.80 |
| 2025-06-30 | 13.32% | +4.06 | 1.073 | $620.50 |
| 2025-06-27 | 12.70% | +3.85 | — | $617.31 |
| 2025-06-26 | 12.90% | +4.09 | 1.105 | $614.10 |
| 2025-06-25 | 13.26% | +4.45 | 1.091 | $609.22 |
| 2025-06-24 | 13.46% | +4.75 | 1.082 | $609.22 |
| 2025-06-23 | 14.83% | +6.09 | 1.058 | $602.52 |
| 2025-06-20 | 15.76% | +6.57 | 1.041 | $596.78 |
| 2025-06-18 | 15.88% | +6.58 | 1.024 | $598.09 |
The chart covers every session in the archive, 321 in total. The table lists the most recent 120.
25-delta risk reversal
Last 321 sessions
The dashed line marks zero, where the 25-delta put and call carry the same implied volatility.
Skew curve
Implied volatility by delta, front expirations
Implied volatility by delta
3d (2026-11-09) · 4d (2026-11-10) · 5d (2026-11-11)
The axis is call delta. Readings to the right of the dashed centre line are taken from the out-of-the-money put at that strike, which is the contract whose quote the volatility was solved from. Points are only plotted where surviving quotes bracket the delta on both sides; nothing is extrapolated past the last traded strike.
Show the underlying numbers
| Delta | 3d | 4d | 5d |
|---|---|---|---|
| 5Δ call | 13.77% | 15.47% | 15.59% |
| 10Δ call | 14.19% | 16.33% | 16.57% |
| 15Δ call | 14.57% | 16.98% | 17.36% |
| 20Δ call | 14.92% | 17.55% | 18.03% |
| 25Δ call | 15.23% | 18.05% | 18.62% |
| 30Δ call | 15.56% | 18.53% | 19.17% |
| 35Δ call | 15.91% | 18.97% | 19.68% |
| 40Δ call | 16.22% | 19.39% | 20.18% |
| 45Δ call | 16.58% | 19.82% | 20.69% |
| ATM | 16.98% | 20.27% | 21.18% |
| 45Δ put | 17.53% | 20.95% | 21.90% |
| 40Δ put | 17.95% | 21.47% | 22.47% |
| 35Δ put | 18.40% | 22.05% | 23.09% |
| 30Δ put | 18.94% | 22.59% | 23.78% |
| 25Δ put | 19.50% | 23.48% | 24.78% |
| 20Δ put | 20.17% | 24.39% | 25.81% |
| 15Δ put | 21.00% | 25.77% | 27.38% |
| 10Δ put | 22.29% | 27.83% | 29.77% |
| 5Δ put | 25.00% | 32.71% | 35.52% |
Wing readings by expiration
| Expiration | Days | Forward | ATM IV | 25Δ put | 25Δ call | RR | Butterfly | Quotes |
|---|---|---|---|---|---|---|---|---|
| 2026-11-09 | 3 | $739.82 | 16.98% | 19.50% | 15.23% | +4.27 | +0.39 | 181 |
| 2026-11-10 | 4 | $739.94 | 20.27% | 23.48% | 18.05% | +5.43 | +0.49 | 120 |
| 2026-11-11 | 5 | $739.94 | 21.18% | 24.78% | 18.62% | +6.17 | +0.52 | 125 |
| 2026-11-12 | 6 | $739.95 | 21.70% | 25.37% | 18.89% | +6.49 | +0.43 | 130 |
| 2026-11-13 | 7 | $740.09 | 22.02% | 25.88% | 18.91% | +6.97 | +0.38 | 161 |
| 2026-11-16 | 10 | $740.07 | 19.98% | 23.87% | 16.97% | +6.90 | +0.45 | 132 |
| 2026-11-17 | 11 | $740.13 | 20.25% | 24.47% | 17.06% | +7.41 | +0.52 | 122 |
| 2026-11-18 | 12 | $740.18 | 20.62% | 25.20% | 17.36% | +7.84 | +0.66 | 131 |
| 2026-11-19 | 13 | $740.17 | 20.69% | 25.39% | 17.34% | +8.05 | +0.68 | 138 |
| 2026-11-20 | 14 | $740.36 | 20.80% | 25.66% | 17.33% | +8.32 | +0.70 | 240 |
| 2026-11-23 | 17 | $740.45 | 19.65% | 24.42% | 16.31% | +8.10 | +0.72 | 116 |
| 2026-11-24 | 18 | $740.47 | 19.70% | 24.55% | 16.32% | +8.22 | +0.74 | 113 |
| 2026-11-25 | 19 | $740.62 | 19.72% | 24.68% | 16.30% | +8.39 | +0.76 | 122 |
| 2026-11-27 | 21 | $740.96 | 19.14% | 24.17% | 15.76% | +8.41 | +0.83 | 181 |
| 2026-11-30 | 24 | $741.01 | 18.58% | 23.53% | 15.35% | +8.18 | +0.86 | 201 |
| 2026-12-01 | 25 | $741.02 | 18.62% | 23.63% | 15.36% | +8.27 | +0.87 | 91 |
| 2026-12-02 | 26 | $741.07 | 18.70% | 23.82% | 15.40% | +8.42 | +0.91 | 83 |
| 2026-12-03 | 27 | $741.00 | 18.75% | 23.88% | 15.43% | +8.45 | +0.90 | 78 |
| 2026-12-04 | 28 | $741.21 | 18.84% | 24.15% | 15.51% | +8.63 | +0.99 | 134 |
| 2026-12-07 | 31 | $741.17 | 18.40% | 23.56% | 15.13% | +8.43 | +0.95 | 39 |
| 2026-12-08 | 32 | $741.28 | 18.44% | 23.65% | 15.17% | +8.48 | +0.97 | 47 |
| 2026-12-10 | 34 | $741.41 | 18.75% | 24.13% | 15.44% | +8.69 | +1.03 | 37 |
| 2026-12-11 | 35 | $741.62 | 18.84% | 24.19% | 15.46% | +8.73 | +0.98 | 116 |
| 2026-12-14 | 38 | $741.67 | 18.38% | 23.79% | 15.12% | +8.66 | +1.07 | 26 |
| 2026-12-18 | 42 | $742.04 | 18.61% | 24.14% | 15.28% | +8.85 | +1.10 | 181 |
| 2026-12-31 | 55 | $743.16 | 18.01% | 23.32% | 14.77% | +8.55 | +1.04 | 217 |
| 2027-01-08 | 63 | $743.99 | 17.82% | 23.06% | 14.66% | +8.41 | +1.04 | 49 |
| 2027-01-15 | 70 | $744.70 | 17.73% | 22.98% | 14.60% | +8.38 | +1.06 | 72 |
| 2027-01-29 | 84 | $745.75 | 17.59% | 22.81% | 14.53% | +8.28 | +1.08 | 158 |
| 2027-02-19 | 105 | $747.21 | 17.40% | 22.65% | 14.43% | +8.22 | +1.14 | 145 |
| 2027-02-26 | 112 | $747.71 | 17.40% | 22.63% | 14.42% | +8.22 | +1.12 | 117 |
| 2027-03-19 | 133 | $749.06 | 17.41% | 22.64% | 14.43% | +8.20 | +1.12 | 157 |
| 2027-03-31 | 145 | $749.91 | 17.30% | 22.45% | 14.35% | +8.10 | +1.10 | 94 |
| 2027-04-16 | 161 | $751.48 | 17.36% | 22.52% | 14.39% | +8.14 | +1.10 | 182 |
| 2027-04-30 | 175 | $752.77 | 17.40% | 22.52% | 14.42% | +8.09 | +1.07 | 47 |
| 2027-05-21 | 196 | $754.29 | 17.45% | 22.54% | 14.48% | +8.06 | +1.06 | 117 |
| 2027-06-17 | 223 | $756.38 | 17.44% | 22.45% | 14.47% | +7.98 | +1.01 | 206 |
| 2027-07-16 | 252 | $758.82 | 17.43% | 22.41% | 14.49% | +7.92 | +1.02 | 101 |
| 2027-08-20 | 287 | $761.75 | 17.50% | 22.42% | 14.59% | +7.83 | +1.01 | 90 |
| 2027-09-17 | 315 | $763.90 | 17.50% | 22.38% | 14.62% | +7.76 | +1.00 | 112 |
| 2027-10-15 | 343 | $766.31 | 17.54% | 22.37% | 14.70% | +7.68 | +1.00 | 100 |
| 2027-11-19 | 378 | $769.20 | 17.56% | 22.37% | 14.77% | +7.60 | +1.01 | 67 |
Each curve above is one expiration. The vertical position is implied volatility; the horizontal position is the delta of the contract it was read from. For US equities the curve normally slopes upward to the right, meaning out-of-the-money puts carry higher implied volatility than equidistant calls.
The 25-delta risk reversal summarises that slope as a single number: the 25-delta put volatility minus the 25-delta call volatility. The butterfly summarises the curvature: the average of the two wings minus the at-the-money reading.
Term structure
At-the-money implied volatility by expiration
At-the-money implied volatility by expiration
42 listed expirations produced a usable reading
The horizontal axis is the square root of days to expiration, which is the scale volatility lives on. A curve that is flat in variance terms plots as a straight line here rather than bending sharply through the front week.
Show the underlying numbers
| Expiration | Days | Forward | ATM IV | ATM strike | Quotes used |
|---|---|---|---|---|---|
| 2026-11-09 | 3 days | $739.82 | 16.98% | $739.91 | 181 |
| 2026-11-10 | 4 days | $739.94 | 20.27% | $740.11 | 120 |
| 2026-11-11 | 5 days | $739.94 | 21.18% | $740.17 | 125 |
| 2026-11-12 | 6 days | $739.95 | 21.70% | $740.24 | 130 |
| 2026-11-13 | 7 days | $740.09 | 22.02% | $740.43 | 161 |
| 2026-11-16 | 10 days | $740.07 | 19.98% | $740.47 | 132 |
| 2026-11-17 | 11 days | $740.13 | 20.25% | $740.58 | 122 |
| 2026-11-18 | 12 days | $740.18 | 20.62% | $740.69 | 131 |
| 2026-11-19 | 13 days | $740.17 | 20.69% | $740.73 | 138 |
| 2026-11-20 | 14 days | $740.36 | 20.80% | $740.97 | 240 |
| 2026-11-23 | 17 days | $740.45 | 19.65% | $741.12 | 116 |
| 2026-11-24 | 18 days | $740.47 | 19.70% | $741.18 | 113 |
| 2026-11-25 | 19 days | $740.62 | 19.72% | $741.37 | 122 |
| 2026-11-27 | 21 days | $740.96 | 19.14% | $741.75 | 181 |
| 2026-11-30 | 24 days | $741.01 | 18.58% | $741.85 | 201 |
| 2026-12-01 | 25 days | $741.02 | 18.62% | $741.90 | 91 |
| 2026-12-02 | 26 days | $741.07 | 18.70% | $741.99 | 83 |
| 2026-12-03 | 27 days | $741.00 | 18.75% | $741.96 | 78 |
| 2026-12-04 | 28 days | $741.21 | 18.84% | $742.22 | 134 |
| 2026-12-07 | 31 days | $741.17 | 18.40% | $742.23 | 39 |
| 2026-12-08 | 32 days | $741.28 | 18.44% | $742.39 | 47 |
| 2026-12-10 | 34 days | $741.41 | 18.75% | $742.62 | 37 |
| 2026-12-11 | 35 days | $741.62 | 18.84% | $742.88 | 116 |
| 2026-12-14 | 38 days | $741.67 | 18.38% | $742.97 | 26 |
| 2026-12-18 | 42 days | $742.04 | 18.61% | $743.52 | 181 |
| 2026-12-31 | 55 days | $743.16 | 18.01% | $744.97 | 217 |
| 2027-01-08 | 63 days | $743.99 | 17.82% | $746.03 | 49 |
| 2027-01-15 | 70 days | $744.70 | 17.73% | $746.95 | 72 |
| 2027-01-29 | 84 days | $745.75 | 17.59% | $748.41 | 158 |
| 2027-02-19 | 105 days | $747.21 | 17.40% | $750.47 | 145 |
| 2027-02-26 | 112 days | $747.71 | 17.40% | $751.19 | 117 |
| 2027-03-19 | 133 days | $749.06 | 17.41% | $753.20 | 157 |
| 2027-03-31 | 145 days | $749.91 | 17.30% | $754.38 | 94 |
| 2027-04-16 | 161 days | $751.48 | 17.36% | $756.49 | 182 |
| 2027-04-30 | 175 days | $752.77 | 17.40% | $758.26 | 47 |
| 2027-05-21 | 196 days | $754.29 | 17.45% | $760.49 | 117 |
| 2027-06-17 | 223 days | $756.38 | 17.44% | $763.45 | 206 |
| 2027-07-16 | 252 days | $758.82 | 17.43% | $766.82 | 101 |
| 2027-08-20 | 287 days | $761.75 | 17.50% | $770.98 | 90 |
| 2027-09-17 | 315 days | $763.90 | 17.50% | $774.06 | 112 |
| 2027-10-15 | 343 days | $766.31 | 17.54% | $777.46 | 100 |
| 2027-11-19 | 378 days | $769.20 | 17.56% | $781.58 | 67 |
Constant maturities
Interpolated between the bracketing listed expirations, in total variance
- 30 days
- 18.53%
- 60 days
- 17.88%
- 90 days
- 17.53%
- 180 days
- 17.42%
Interpolation is linear in total variance, not in volatility. Interpolating volatility directly implies a forward variance that can be negative between two expirations. A tenor beyond the longest listed expiration is reported as unavailable rather than extrapolated.
Term structure slope
Last 321 sessions
The dashed line marks 1.00, where the 90-day and 30-day at-the-money volatilities are equal. Above it the longer tenor carries the higher volatility.
The term structure is the at-the-money implied volatility of each listed expiration, plotted against how far away that expiration is. Its usual shape for a calm underlying slopes gently upward, because a longer horizon admits more uncertainty.
It inverts when the market prices a dated event: an expiration that captures a scheduled announcement carries the variance of that event on top of ordinary trading, so a shorter contract can print a higher volatility than a longer one.