Options Skew Analytics

XBI options analytics

XBI · ETF

Data as of 23 September 2026 (end of day)

XBI options are pricing a 30-day at-the-money volatility of 31.0%, a move of about ±8.9% over the next month. That is higher than 74% of the 213 sessions in its trailing year.

Its 25-delta puts carry 2.90 volatility points more than the calls, around the middle of its own range for the past year.

Current readings

30-day ATM implied volatilityⓘ
31.03%

Prices a move of about ±8.9% over 30 days, or ±2.0% on a typical day.

Higher than 74% of the past year.

25-delta risk reversalⓘ
+2.90

Puts carry 2.90 volatility points more than calls the same distance from the money.

Higher than 46% of the past year.

25-delta butterflyⓘ
+0.97

The wings carry 0.97 volatility points more than at-the-money.

Term structure slopeⓘ
1.016

90-day volatility is 2% above 30-day.

Higher than 69% of the past year.

Where 30-day implied volatility sits

Against 213 prior sessions (one-year window)

31.0% — 74th percentile
21.7%56.7%
IV percentile, 1 year
74%
IV rank, 1 year
27%
IV percentile, 2 years
74%
IV rank, 2 years
27%

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
$155.20
30-day implied forward
$156.00
60-day ATM IV
30.74%
90-day ATM IV
31.53%
180-day ATM IV
31.66%
Expirations used
10
Total open interest
328,415
Put / call open interest
0.94

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 220 sessions

10%20%30%40%50%60%6 Sep22 Nov13 Feb6 May23 Sep
Show the underlying numbers (most recent 120)
Session30-day ATM IV25-delta RRTerm slopeClose
2026-09-2331.03%+2.901.016$155.20
2026-09-2230.38%+2.560.996$161.87
2026-09-2130.08%+2.261.009$158.23
2026-09-1829.26%+2.001.021$156.72
2026-09-1730.31%+2.830.998$158.25
2026-09-1628.92%+5.861.052$154.18
2026-09-1530.89%+2.350.976$154.03
2026-09-1429.95%+2.071.010$157.60
2026-09-1128.07%+0.061.034$156.20
2026-09-10———$156.82
2026-09-0929.77%-0.321.017$159.38
2026-09-0829.38%+1.481.004$161.93
2026-09-0429.46%+0.701.046$163.81
2026-09-0331.11%+3.190.991$164.38
2026-09-02———$165.37
2026-09-0130.21%+1.011.044$163.40
2026-08-31———$162.50
2026-08-2829.13%+1.411.074$162.38
2026-08-2731.48%+2.000.990$168.23
2025-06-3027.17%+3.081.002$82.93
2025-06-2723.22%+3.481.147$83.01
2025-06-2625.09%+2.021.067$83.68
2025-06-2527.60%+2.151.007$83.27
2025-06-2427.94%+2.760.998$83.82
2025-06-2329.32%+3.670.986$82.27
2025-06-2029.87%+3.740.994$82.38
2025-06-1829.45%+4.170.979$82.66
2025-06-1730.70%+4.120.954$82.10
2025-06-1629.97%+3.900.930$83.37
2025-06-1330.22%+2.770.942$83.60
2025-06-1228.74%+2.880.970$84.36
2025-06-1129.04%+3.040.983$84.37
2025-06-1027.99%+3.051.041$85.28
2025-06-0927.53%+2.131.002$84.27
2025-06-0627.81%+1.611.012$84.26
2025-06-0529.18%+2.431.008$82.56
2025-06-0429.69%+1.330.997$82.48
2025-06-0327.51%+2.561.008$82.34
2025-06-0227.15%+6.421.003$81.24
2025-05-3029.87%+3.300.997$79.19
2025-05-2930.75%+4.620.928$80.46
2025-05-2831.60%+3.780.962$78.77
2025-05-2737.04%+5.020.857$79.30
2025-05-2332.32%+5.340.893$79.04
2025-05-2233.29%+2.560.865$79.25
2025-05-2132.66%+4.940.953$79.33
2025-05-2030.86%+4.180.935$81.40
2025-05-1931.51%+4.230.955$79.72
2025-05-1631.05%+5.700.960$79.02
2025-05-1531.93%+3.910.951$77.58
2025-05-1432.94%+5.390.879$76.37
2025-05-1332.92%+5.280.953$77.55
2025-05-1236.76%+4.030.834$79.45
2025-05-0937.49%+8.330.909$76.39
2025-05-0837.89%+2.250.872$78.04
2025-05-0736.62%+5.730.886$77.35
2025-05-0638.70%+11.030.900$77.17
2025-05-0532.09%+6.010.973$82.65
2025-05-0231.95%+5.730.977$83.50
2025-05-0132.10%+3.850.993$82.50
2025-04-3031.23%+6.830.990$82.95
2025-04-2932.23%+8.310.982$81.88
2025-04-2833.75%+8.450.938$81.37
2025-04-2535.33%+8.390.924$80.25
2025-04-2433.36%+8.781.027$80.89
2025-04-2335.64%+8.671.003$79.10
2025-04-2234.96%+10.151.002$77.64
2025-04-2143.82%+8.020.863$75.51
2025-04-1736.69%+9.390.962$75.93
2025-04-1636.78%+12.630.991$75.13
2025-04-1537.15%+12.010.948$76.54
2025-04-1440.25%+9.780.935$76.54
2025-04-1143.70%+13.990.963$74.33
2025-04-10———$71.61
2025-04-09———$74.88
2025-04-0856.72%+17.820.829$69.80
2025-04-0748.80%+8.790.829$72.99
2025-04-04———$73.66
2025-04-0335.67%+5.720.923$78.14
2025-04-0231.95%+3.670.941$80.59
2025-04-0134.62%+2.840.912$78.16
2025-03-3131.78%+3.140.924$81.10
2025-03-2825.90%+2.211.072$84.40
2025-03-2726.76%+4.171.011$85.53
2025-03-2624.71%-0.161.171$85.08
2025-03-2526.56%+2.250.992$87.08
2025-03-2425.28%+2.621.076$88.82
2025-03-2127.27%+2.440.993$87.12
2025-03-2027.53%+2.941.003$86.59
2025-03-1928.62%+3.600.928$87.46
2025-03-1830.60%+2.710.868$86.17
2025-03-1728.66%+3.291.007$88.29
2025-03-1430.47%+3.940.945$87.13
2025-03-1332.10%+0.850.906$85.97
2025-03-1232.74%+3.610.930$87.15
2025-03-1132.86%+3.580.923$86.17
2025-03-1034.12%+3.480.862$86.24
2025-03-0733.05%+0.030.933$87.30
2025-03-0630.73%+5.170.976$87.06
2025-03-0534.44%+5.910.895$87.82
2025-03-0432.53%+3.300.956$86.13
2025-03-0335.45%+2.750.892$85.60
2025-02-2830.02%+3.820.971$88.71
2025-02-2731.35%+3.410.956$87.10
2025-02-2629.49%+3.831.040$88.25
2025-02-2530.52%+3.040.962$88.69
2025-02-2429.71%+1.330.848$90.11
2025-02-2126.43%+4.950.954$91.70
2025-02-2026.29%+2.061.047$92.72
2025-02-1925.83%-0.840.987$92.53
2025-02-1826.54%+3.411.009$91.33
2025-02-1425.33%+3.191.049$91.41
2025-02-1325.88%+1.191.026$90.77
2025-02-1225.21%+3.791.157$89.97
2025-02-1127.29%+3.040.974$89.05
2025-02-1026.87%+2.690.998$90.34
2025-02-0725.91%+2.741.035$91.24
2025-02-0625.71%+1.250.978$93.37
2025-02-0525.44%+3.311.007$94.70
2025-02-0426.38%+1.770.995$92.57

The chart covers every session in the archive, 220 in total. The table lists the most recent 120.

25-delta risk reversal

Last 220 sessions

-5.00.05.010.015.020.06 Sep22 Nov13 Feb6 May23 Sep

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

2d (2026-09-25) · 9d (2026-10-02) · 16d (2026-10-09)

20%30%40%50%60%2026-09-25 (2d) — 5Δ C — IV 39.53%2026-09-25 (2d) — 10Δ C — IV 39.04%2026-09-25 (2d) — 15Δ C — IV 37.52%2026-09-25 (2d) — 20Δ C — IV 37.45%2026-09-25 (2d) — 25Δ C — IV 38.05%2026-09-25 (2d) — 30Δ C — IV 38.53%2026-09-25 (2d) — 35Δ C — IV 38.69%2026-09-25 (2d) — 40Δ C — IV 38.84%2026-09-25 (2d) — 45Δ C — IV 40.33%2026-09-25 (2d) — ATM — IV 41.73%2026-09-25 (2d) — 45Δ P — IV 42.58%2026-09-25 (2d) — 40Δ P — IV 42.12%2026-09-25 (2d) — 35Δ P — IV 41.30%2026-09-25 (2d) — 30Δ P — IV 41.53%2026-09-25 (2d) — 25Δ P — IV 42.32%2026-09-25 (2d) — 20Δ P — IV 45.83%2026-09-25 (2d) — 15Δ P — IV 47.20%2026-09-25 (2d) — 10Δ P — IV 48.46%2026-09-25 (2d) — 5Δ P — IV 49.46%2d2026-10-02 (9d) — 20Δ C — IV 30.60%2026-10-02 (9d) — 25Δ C — IV 31.45%2026-10-02 (9d) — 30Δ C — IV 31.31%2026-10-02 (9d) — 35Δ C — IV 31.14%2026-10-02 (9d) — 40Δ C — IV 31.57%2026-10-02 (9d) — 45Δ C — IV 31.98%2026-10-02 (9d) — ATM — IV 31.31%2026-10-02 (9d) — 45Δ P — IV 32.65%2026-10-02 (9d) — 40Δ P — IV 31.83%2026-10-02 (9d) — 35Δ P — IV 32.16%2026-10-02 (9d) — 30Δ P — IV 32.91%2026-10-02 (9d) — 25Δ P — IV 34.28%2026-10-02 (9d) — 20Δ P — IV 33.21%2026-10-02 (9d) — 15Δ P — IV 35.60%2026-10-02 (9d) — 10Δ P — IV 35.45%9d2026-10-09 (16d) — 20Δ C — IV 31.78%2026-10-09 (16d) — 25Δ C — IV 30.58%2026-10-09 (16d) — 30Δ C — IV 30.90%2026-10-09 (16d) — 35Δ C — IV 31.39%2026-10-09 (16d) — 40Δ C — IV 31.94%2026-10-09 (16d) — 45Δ C — IV 31.11%2026-10-09 (16d) — ATM — IV 30.39%2026-10-09 (16d) — 45Δ P — IV 30.79%2026-10-09 (16d) — 40Δ P — IV 31.65%2026-10-09 (16d) — 35Δ P — IV 30.33%2026-10-09 (16d) — 30Δ P — IV 32.44%2026-10-09 (16d) — 25Δ P — IV 31.81%2026-10-09 (16d) — 20Δ P — IV 33.58%2026-10-09 (16d) — 15Δ P — IV 33.52%16d10Δ C25Δ CATM25Δ P10Δ Pout-of-the-money calls ← delta → out-of-the-money puts

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
Delta2d9d16d
5Δ call39.53%——
10Δ call39.04%——
15Δ call37.52%——
20Δ call37.45%30.60%31.78%
25Δ call38.05%31.45%30.58%
30Δ call38.53%31.31%30.90%
35Δ call38.69%31.14%31.39%
40Δ call38.84%31.57%31.94%
45Δ call40.33%31.98%31.11%
ATM41.73%31.31%30.39%
45Δ put42.58%32.65%30.79%
40Δ put42.12%31.83%31.65%
35Δ put41.30%32.16%30.33%
30Δ put41.53%32.91%32.44%
25Δ put42.32%34.28%31.81%
20Δ put45.83%33.21%33.58%
15Δ put47.20%35.60%33.52%
10Δ put48.46%35.45%—
5Δ put49.46%——

Wing readings by expiration

ExpirationDaysForwardATM IV25Δ put25Δ callRRButterflyQuotes
2026-09-252$155.7241.73%42.32%38.05%+4.27-1.5515
2026-10-029$155.7631.31%34.28%31.45%+2.83+1.5520
2026-10-0916$155.6030.39%31.81%30.58%+1.24+0.8121
2026-10-1623$156.0832.33%34.26%31.60%+2.66+0.6035
2026-10-2330$156.0031.03%33.45%30.55%+2.90+0.9720
2026-11-2058$156.9230.65%33.54%30.80%+2.73+1.5231
2026-12-1886$157.1531.55%31.85%30.69%+1.16-0.2828
2027-01-15114$157.4431.44%30.98%30.45%+0.53-0.7330
2027-03-19177$158.0831.71%32.31%32.22%+0.09+0.5540
2027-06-17267$160.0330.50%30.56%31.25%-0.69+0.4039

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

10 listed expirations produced a usable reading

25%30%35%40%45%2026-09-25 — 2 days — at-the-money IV 41.73%2026-10-02 — 9 days — at-the-money IV 31.31%2026-10-09 — 16 days — at-the-money IV 30.39%2026-10-16 — 23 days — at-the-money IV 32.33%2026-10-23 — 30 days — at-the-money IV 31.03%2026-11-20 — 58 days — at-the-money IV 30.65%2026-12-18 — 86 days — at-the-money IV 31.55%2027-01-15 — 114 days — at-the-money IV 31.44%2027-03-19 — 177 days — at-the-money IV 31.71%2027-06-17 — 267 days — at-the-money IV 30.50%7306090180days to expiration

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
ExpirationDaysForwardATM IVATM strikeQuotes used
2026-09-252 days$155.7241.73%$155.8015
2026-10-029 days$155.7631.31%$155.9520
2026-10-0916 days$155.6030.39%$155.9121
2026-10-1623 days$156.0832.33%$156.5935
2026-10-2330 days$156.0031.03%$156.6220
2026-11-2058 days$156.9230.65%$158.1031
2026-12-1886 days$157.1531.55%$159.0028
2027-01-15114 days$157.4431.44%$159.8930
2027-03-19177 days$158.0831.71%$161.9840
2027-06-17267 days$160.0330.50%$165.5739

Constant maturities

Interpolated between the bracketing listed expirations, in total variance

30 days
31.03%
60 days
30.74%
90 days
31.53%
180 days
31.66%

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 220 sessions

0.600.801.001.201.406 Sep22 Nov13 Feb6 May23 Sep

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.