Prior comparison unavailable: the published 2026-09-18 edition is verified but ends at 18 Sept, 16:30 UTC; this window requires 18 Sept, 16:59 UTC.
A structured watchlist was not recorded or could not be verified in the prior edition; prior-watch outcomes remain unavailable.
Next daily cutoff: measurable checks
These checks are reconstructed from this edition’s stored endpoints; they were not recorded in the original report.
Hold the observed level: BTC 1W ATM IV ≥ 34.63 percent at . Current level 34.63; threshold is the current observed endpoint.
Full retrace: BTC 1W ATM IV ≤ 32.12 percent at . Current level 34.63; threshold is the previous observed endpoint.
Measurement basis and receipt
These are observed-level conditions for the next aligned cutoff, with no forecast or trade action. Spot uses exact index endpoints where available; ATM IV is quoted in percent and its change, RR25 and BF25 in volatility points. Derived from verified legacy artifact endpoints.
BTC:atmIv:1W:observed-current-level: rows[asset=BTC].report.tenors[tenor=1W].atmIv.previous; rows[asset=BTC].report.tenors[tenor=1W].atmIv.current; rows[asset=BTC].report.tenors[tenor=1W].atmIv.change; evaluation window 2026-09-19T16:59:00+00:00 to 2026-09-20T16:59:00+00:00.
BTC:atmIv:1W:observed-previous-level: rows[asset=BTC].report.tenors[tenor=1W].atmIv.previous; rows[asset=BTC].report.tenors[tenor=1W].atmIv.current; rows[asset=BTC].report.tenors[tenor=1W].atmIv.change; evaluation window 2026-09-19T16:59:00+00:00 to 2026-09-20T16:59:00+00:00.
Chart notes
Combined surface read: ATM IV rose (BTC); RR25 moved toward calls (BTC).
02 · Options market read
What the volatility surface did.
No headline tenor had comparable observations at both endpoints; unavailable values remain suppressed in the tables and charts.
Derived directly from structured Derivasys surface data
03 · Catalyst check
18 Sept 2026, 16:59 UTC to 19 Sept 2026, 16:59 UTC
No catalyst assigned.
No qualifying context was found in the monitored news sources for this reporting window.
04 · Detailed analysis
What changed across the BTC volatility surface.
Implied versus realised
At the 16:59 UTC cutoff, 1W ATM IV was 34.63%, 1.68 volatility points below seven-day realised volatility of 36.31%; 24-hour realised volatility was 27.34% and 30-day realised volatility was 39.38%.
Front end
Front-end ATM IV is unavailable because comparable observations were not present at both snapshots.
Long end
Long-dated ATM IV is unavailable because comparable observations were not present at both snapshots.
Skew
RR25 is unavailable because comparable observations were not present at both snapshots.
Largest standard-tenor move
The largest standard-tenor ATM IV move was +2.51 volatility points at 1W, to 34.63%.
Universe roll: added 23SEP26; removed 19SEP26. Comparisons use common expiries only.
RR25 is unavailable because comparable observations were not present at both snapshots. Negative RR25 denotes a richer 25-delta put wing under the call-minus-put convention.
Contracts with fewer than 2 full days to expiry remain in the tables but are excluded from headline rankings. Settlement proximity, time decay, changing liquidity and fewer quotes can exaggerate their changes.
0.6d
Smile rotation
20SEP26, +17.24 vol pts1.6d
Smile rotation
21SEP26, +8.33 vol pts
10 · Volatility term structure
Today against the previous 24-hour snapshot.
Only fixed tenors bracketed by listed expiries at both snapshots are charted. The listed-expiry table preserves the observable exchange maturities underneath those interpolated points.
CurrentComparison snapshot
Suppressed outside the observable listed-expiry range: 1Y.
Expiry
Time left
Forward now (USD)
Forward change (USD)
ATM IV now
ATM IV change
RR25 change
BF25 change
20SEP26Expiry effect
0.6 days
81,838.22
+1015.09 USD
25.28%
+2.73 vol pts
+2.74 vol pts
Unavailable
21SEP26Expiry effect
1.6 days
81,866.82
+1032.85 USD
23.48%
-1.33 vol pts
+1.57 vol pts
Unavailable
22SEP26
2.6 days
81,881.45
+1036.32 USD
30.04%
+1.60 vol pts
+0.17 vol pts
Unavailable
25SEP26
5.6 days
81,915.47
+1042.51 USD
34.41%
+2.43 vol pts
+0.03 vol pts
Unavailable
2OCT26
12.6 days
82,000.93
+1047.30 USD
35.04%
+1.72 vol pts
+0.63 vol pts
Unavailable
9OCT26
19.6 days
82,061.13
+1044.40 USD
34.58%
+1.56 vol pts
+0.62 vol pts
Unavailable
30OCT26
40.6 days
82,329.48
+1072.12 USD
34.22%
+0.30 vol pts
-0.23 vol pts
Unavailable
27NOV26
68.6 days
82,656.66
+1091.53 USD
36.01%
-0.10 vol pts
+0.05 vol pts
Unavailable
25DEC26
96.6 days
82,984.25
+1077.20 USD
36.88%
-0.12 vol pts
-0.02 vol pts
Unavailable
26MAR27
187.6 days
83,968.55
+1073.68 USD
38.39%
+0.14 vol pts
-0.07 vol pts
Unavailable
25JUN27
278.6 days
84,991.84
+1074.24 USD
39.63%
+0.18 vol pts
-0.07 vol pts
Unavailable
11 · Smile movement
Reconstructed SVI smiles for every common expiry.
Each overlay uses the stored five-parameter SVI fit and the snapshot-specific time to expiry. Ultra-short expiries are displayed but do not determine the headline ranking.
20SEP26rotation towards calls · wing steepening21SEP26rotation towards calls · wing steepening22SEP26rotation towards calls · wing steepening25SEP26rotation towards puts · wing steepening2OCT26rotation towards calls · wing steepening9OCT26parallel shift higher · rotation towards calls · wing steepening30OCT26parallel shift higher27NOV26parallel shift lower25DEC26parallel shift lower26MAR27parallel shift higher25JUN27parallel shift higher
Surface movement heatmap
Each cell is the fitted IV change in volatility points. Rows are listed expiries; columns run from the put wing through ATM to the call wing.
IV lowerIV higher
20SEP26
21SEP26
22SEP26
25SEP26
2OCT26
9OCT26
30OCT26
27NOV26
25DEC26
26MAR27
25JUN27
-0.30kATM+0.30k
Completed-session cross-asset context
Crypto volatility against US equity risk.
BTC 30-day implied volatility was 2.3 times VIX, while its 30-session return correlation with SPX was low at 0.27.
Implied-volatility premium
BTC 30-day ATM IV was 34.22%, against VIX at 14.81: a 19.41-point spread and 2.31× ratio.
Daily-close realised-volatility regime
BTC reported crypto realised volatility was 42.30%, versus SPX reported realised volatility of 9.38%.
Equity co-movement
Return correlation with SPX was 0.265 over 30 aligned sessions and 0.270 over 60 sessions. VIX9D, VIX and VIX3M closed at 12.27, 14.81 and 18.24.
RV comparison basis unverified: this edition does not record the recognised provider methodology for both horizons and annualisation conventions. Any historical spread rank should not be interpreted as establishing matched-horizon comparability.
As of 18 Sept 2026, 20:00 UTC. Implied volatility and completed-session realised volatility use their respective observation windows shown above.
Evidence and methodology
Crypto RV uses sqrt(365); SPX RV uses sqrt(252).
RV observation windows and sampling
The RV comparisons use one-minute index returns, annualised on a 365-day basis. No coverage policy was recorded in this edition; read the recorded window availability and coverage below.
Evidence, source data and methodology
Report comparison baseline → current snapshot
2026-09-18 16:59:00 UTC → 2026-09-19 16:59:00 UTC
Changes use these stored market-snapshot baselines. The comparison baseline may differ from the snapshot used in the previous published edition.
Reader summary (BF-specific claims withheld)
Bitcoin’s 24-hour spot-index return was 1.22%, and Bitcoin one-week ATM IV was 1.68 points below seven-day realised volatility at the cutoff. Derivasys data show the front end repriced more than longer maturities.
At report cutoff · Levels and stored endpoint changes
What matters now
Vol: BTC 1W ATM IV 34.63% · Δ +2.51 vol pts
Skew: BTC 1W RR25 1.25 vol pts · Δ +0.19 vol pts
Curve: BTC 6M minus 1W ATM IV spread +3.71 vol pts · spread Δ -2.37 vol pts
Vol
BTC 1W ATM IV 34.63% · Δ +2.51 vol ptspercentile rank 66.9% by absolute move · full history (n=148)
Technical appendix: measurement and history provenance
Original edition evidence follows unchanged. Its BF slots retain the original full fly25 or unverified basis; these receipts do not validate canonical BF25 history or ranks.
These diagnostics preserve the fitted-surface audit trail without competing with the main market story.
Show SVI parameter changes and normalized Greeks
SVI diagnostics
Daily movement in a, b, rho, m and sigma.
Among ranking-eligible expiries, the largest absolute rho change occurred at 25DEC26; the largest sigma change occurred at 22SEP26.
Expiry
Δ a
Δ b
Δ rho
Δ m
Δ sigma
Smile classification
20SEP26
+0.01220
-0.02070
+0.12770
+0.02040
-0.12140
rotation towards calls, wing steepening
21SEP26
+0.02580
-0.03240
+0.09090
+0.02010
-0.19590
rotation towards calls, wing steepening
22SEP26
+0.01880
-0.00710
+0.03040
+0.00600
-0.15490
rotation towards calls, wing steepening
25SEP26
+0.01280
-0.00370
-0.00830
+0.00720
-0.08880
rotation towards puts, wing steepening
2OCT26
+0.02130
-0.00190
-0.04760
-0.00510
-0.14140
rotation towards calls, wing steepening
9OCT26
+0.01850
-0.00510
-0.02850
+0.00190
-0.09450
parallel shift higher, rotation towards calls, wing steepening
30OCT26
+0.01990
-0.01540
+0.00480
+0.03610
-0.06410
parallel shift higher
27NOV26
+0.01580
-0.00820
-0.01870
+0.00840
-0.05050
parallel shift lower
25DEC26
+0.05000
-0.02010
-0.07310
-0.03960
-0.10740
parallel shift lower
26MAR27
+0.00870
-0.00860
-0.00620
-0.00380
+0.00150
parallel shift higher
25JUN27
+0.01320
-0.00210
-0.04990
-0.05340
-0.01620
parallel shift higher
Current surface characteristics
Where normalized model Greek intensity is highest.
These are comparable Black-forward Greeks for a one-BTC ATM-forward call at each listed expiry—not portfolio exposure, open interest or a prediction of dealer positioning.
Thresholds are asset-specific policies recorded in this edition. Each window is assessed independently; returns spanning gaps are excluded. Partial estimates may miss volatility during gaps.
RV coverage and methodology
BTC · Unavailable · Surface cutoff 19 Sept 2026, 16:59:00 UTC · 7D coverage not recorded / not recorded required · largest 7D gap not recorded / not recorded maximum · maximum gap not recorded. RV suppressed — valid 7D coverage was not recorded. Full 7D coverage policy was not recorded.
Fixed-tenor measures are published only when listed expiries bracket the target at both comparison snapshots. Targets outside either observable range are suppressed, not extrapolated; headline rankings use only supported tenors.
Smile reconstruction
Listed-expiry smiles are reconstructed from stored SVI total-variance parameters on a fixed log-moneyness grid.
Ultra-short expiries
Expiries with fewer than 2 full days remaining stay in detailed tables but are excluded from headline rankings. Settlement proximity, time decay, changing liquidity and fewer quotes can exaggerate their changes.
Greek normalization
Black forward Greeks for a normalized one-BTC ATM-forward call, zero rate, fitted SVI IV
Catalyst policy
Only sufficiently relevant, reliably sourced events are shown; otherwise no catalyst is assigned.
