Prior comparison unavailable: the published 2026-09-19 edition is verified but ends at 19 Sept, 16:59 UTC; this window requires 19 Sept, 16:30 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 ≤ 33.98 percent at . Current level 33.98; threshold is the current observed endpoint.
Full retrace: BTC 1W ATM IV ≥ 34.28 percent at . Current level 33.98; 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 2026-09-20T16:30:00+00:00 to 2026-09-21T16:30:00+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 2026-09-20T16:30:00+00:00 to 2026-09-21T16:30:00+00:00.
Chart notes
Combined surface read: ATM IV fell (BTC); RR25 moved toward puts (BTC).
01 · Daily briefing
Macro · Crypto · Options
The day in markets.
Smile rotation is the fitted IV change at +0.15 log-moneyness minus the change at −0.15, in volatility points. A positive reading indicates a relative shift toward the call side.
Bitcoin skew shifts toward puts
Bitcoin two-week RR25 crossed below zero as short-dated implied volatility softened at the cutoff.
Macro
No qualifying macro context was retained.
Crypto
The Block reported Friday net inflows into Bitcoin ETFs and an end to Ether funds’ four-week inflow streak.
Links identify the underlying reporting for retained events; entries without a retained link are marked.
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
19 Sept 2026, 16:30 UTC to 20 Sept 2026, 16:30 UTC
Relevant context found; no confirmed catalyst
Relevant market event
1 relevant event was retained for the comparison window.
Confidencelow causal confidence
News is presented as contextual association unless the structured evidence supports a stronger relationship.
04 · Detailed analysis
What changed across the BTC volatility surface.
Implied versus realised
At the 16:30 UTC cutoff, 1W ATM IV was 33.98%, 3.14 volatility points below seven-day realised volatility of 37.12%; 24-hour realised volatility was 25.73% and 30-day realised volatility was 37.29%.
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 -0.85 volatility points at 2W, to 33.70%.
Universe roll: added 24SEP26; removed 20SEP26. 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
21SEP26, -8.18 vol pts1.6d
Smile rotation
22SEP26, -4.21 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
21SEP26Expiry effect
0.6 days
81,176.35
-649.71 USD
30.91%
+6.98 vol pts
-1.35 vol pts
Unavailable
22SEP26Expiry effect
1.6 days
81,197.34
-640.64 USD
31.64%
+2.65 vol pts
-1.04 vol pts
Unavailable
23SEP26
2.6 days
81,212.63
-639.28 USD
32.70%
+1.71 vol pts
-1.70 vol pts
Unavailable
25SEP26
4.6 days
81,244.18
-623.73 USD
34.15%
+0.15 vol pts
-1.29 vol pts
Unavailable
2OCT26
11.6 days
81,320.03
-635.31 USD
33.84%
-0.95 vol pts
-1.05 vol pts
Unavailable
9OCT26
18.6 days
81,392.66
-630.70 USD
33.53%
-0.35 vol pts
-1.24 vol pts
Unavailable
30OCT26
39.6 days
81,655.54
-624.56 USD
34.23%
+0.17 vol pts
-0.62 vol pts
Unavailable
27NOV26
67.6 days
81,951.56
-651.10 USD
36.25%
+0.27 vol pts
-0.33 vol pts
Unavailable
25DEC26
95.6 days
82,318.38
-618.12 USD
37.15%
+0.28 vol pts
-0.19 vol pts
Unavailable
26MAR27
186.6 days
83,320.95
-602.80 USD
38.54%
+0.23 vol pts
+0.09 vol pts
Unavailable
25JUN27
277.6 days
84,333.11
-621.22 USD
39.63%
+0.05 vol pts
-0.02 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.
21SEP26rotation towards puts · wing steepening22SEP26rotation towards puts · wing steepening23SEP26rotation towards puts · wing steepening25SEP26rotation towards puts · wing steepening2OCT26rotation towards puts · wing steepening9OCT26rotation towards puts · wing flattening30OCT26rotation towards puts27NOV26parallel shift higher25DEC26parallel shift higher26MAR27parallel 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
21SEP26
22SEP26
23SEP26
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
Derivasys cross-asset metrics at 2026-09-18T20:00:00Z; crypto RV annualizes with sqrt(365), SPX RV with 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
2026-09-19 16:30:00 UTC → 2026-09-20 16:30:00 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 two-week RR25 fell 1.28 volatility points to -0.26 volatility points at the 16:30 UTC cutoff, moving from call-rich to put-rich pricing and marking a notable 80.5 percentile move in comparable history. Bitcoin two-week ATM IV simultaneously fell 0.85 points to 33.70%, while Bitcoin’s 24-hour spot-index return was -0.83%. Derivasys data show one-week ATM IV at 33.98%, 3.14 points below seven-day realised volatility of 37.12%.
At report cutoff · Levels and stored endpoint changes
What matters now
Vol: BTC 1W ATM IV 33.98% · Δ -0.30 vol pts
Skew: BTC 1W RR25 -0.11 vol pts · Δ -1.08 vol pts
Curve: BTC 6M minus 1W ATM IV spread +4.52 vol pts · spread Δ +0.54 vol pts
Vol
BTC 1W ATM IV 33.98% · Δ -0.30 vol ptspercentile rank 8.7% by absolute move · full history (n=149)
Skew
BTC 1W RR25 -0.11 vol pts · Δ -1.08 vol ptspercentile rank 66.4% by absolute move · full history (n=149)
Wings
BTC Unavailable
IV versus RV
BTC Unavailable
Unavailable readings: BTC Wings; BTC IV versus RV. See the report’s data availability notes.
Δ compares the report’s stored surface endpoints. IV versus RV is a level comparison, not a daily change.
Historical move evidence
BTC 1W ATM IV: percentile rank 8.7% by absolute move · full history (n=149)
BTC 1W RR25: percentile rank 66.4% by absolute move · full history (n=149)
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 30OCT26; the largest sigma change occurred at 9OCT26.
Expiry
Δ a
Δ b
Δ rho
Δ m
Δ sigma
Smile classification
21SEP26
+0.00940
-0.01420
-0.09090
-0.01970
-0.10060
rotation towards puts, wing steepening
22SEP26
+0.00320
-0.01040
-0.04920
-0.01270
+0.00220
rotation towards puts, wing steepening
23SEP26
-0.00250
+0.00150
-0.04110
-0.00860
+0.01490
rotation towards puts, wing steepening
25SEP26
-0.01740
+0.01280
+0.03220
+0.02120
+0.07620
rotation towards puts, wing steepening
2OCT26
-0.02460
+0.01750
+0.01400
+0.00600
+0.08320
rotation towards puts, wing steepening
9OCT26
-0.05000
+0.01930
+0.01960
-0.03060
+0.21970
rotation towards puts, wing flattening
30OCT26
-0.01930
-0.00230
+0.09870
+0.06500
+0.08810
rotation towards puts
27NOV26
-0.04480
+0.02260
+0.02330
-0.03550
+0.13370
parallel shift higher
25DEC26
-0.02760
+0.01270
-0.03660
-0.06560
+0.07710
parallel shift higher
26MAR27
-0.00100
+0.00220
-0.05950
-0.07450
+0.01480
parallel shift higher
25JUN27
-0.00020
-0.00480
-0.00620
-0.01090
+0.01830
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 20 Sept 2026, 16:30:00 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.
