Name: Weekly BTC options surface changes through 2026-07-28
Creator: Derivasys
License: https://www.derivasys.com/research-artifact-license/v1

02 · Options market read

What the volatility surface did.

6 of 6 headline tenors were comparable at both endpoints. The largest ATM IV move was 2W at -0.36 volatility points, to 34.96%.

Derived directly from structured Derivasys surface data

Relevant context found; no confirmed catalyst

Relevant market events

2 events were retained after relevance scoring and event-level deduplication.

Confidencemedium causal confidence

News is presented as contextual association unless the structured evidence supports a stronger relationship.

Selected events

01
Monetary policy decisionsEuropean Central Bank · 12:15 UTC
macro · neutral · low confidence
Why selected: Selected as macro context because the report records ATM IV 2W: down 0.36 points to 34.96%; ATM slope 1Y-minus-1W: -0.53 points to 6.79 points.
Matched signals: ATM IV 2W: down 0.36 points to 34.96%; ATM slope 1Y-minus-1W: -0.53 points to 6.79 points
02
Crypto Derivatives: Analytics Report – Week 30Deribit Insights · 20:02 UTC
direct options · contrary · medium confidence
Why selected: Selected as direct options context because the report records ATM IV 2W: down 0.36 points to 34.96%; RR25 2W: 3.74 points toward puts to -4.70% (put-rich); BF25 1W: up 0.55 points to 2.33%.
Matched signals: ATM IV 2W: down 0.36 points to 34.96%; RR25 2W: 3.74 points toward puts to -4.70% (put-rich); BF25 1W: up 0.55 points to 2.33%

04 · Detailed surface analysis

What changed across the BTC volatility surface.

Front end

Front-end ATM IV decreased, averaging -0.11 volatility points to 35.10% across 1W, 2W and 1M.

Long end

Long-dated ATM IV decreased, averaging -0.28 volatility points to 41.34% across 6M and 1Y.

Skew

RR25 moved towards puts, averaging -1.71 volatility points to -4.47% across the six available headline tenors.

Convexity

BF25 increased, averaging +0.14 volatility points to 2.53% across the six available headline tenors.

Largest standard-tenor move

The largest standard-tenor ATM IV move was -0.36 volatility points at 2W, to 34.96%.

Weekly universe roll: added 14AUG26, 1AUG26, 29JUL26, 30JUL26; removed 22JUL26, 23JUL26, 24JUL26, 25JUL26. Listed-expiry changes use contracts present at both endpoints.

05 · Seven-day ranking

Largest weekly surface events

Largest eligible smile rotation

31JUL26, -9.87 vol pts

Largest standard-tenor RR25 move

2W, -3.74 vol pts

Largest standard-tenor BF25 move

1W, +0.55 vol pts

Largest standard-tenor ATM IV move

2W, -0.36 vol pts

Largest eligible SVI rho move

25JUN27, +0.1455 param

Largest eligible SVI sigma move

7AUG26, -0.1080 param

06 · ATM volatility

Week-end against week-opening ATM volatility.

Tenor	Week end (vol %)	Week start (vol %)	Change (vol pts)	Relative change
1W	35.50	35.24	+0.26 vol pts	+0.74%
2W	34.96	35.32	-0.36 vol pts	-1.02%
1M	34.83	35.06	-0.23 vol pts	-0.66%
3M	38.30	37.99	+0.31 vol pts	+0.82%
6M	40.39	40.68	-0.29 vol pts	-0.71%
9M	41.51	41.75	-0.24 vol pts	-0.57%
1Y	42.29	42.56	-0.27 vol pts	-0.63%

07 · During the week

Ranges and largest day-to-day repricings.

The generator sampled the final successful BTC surface on each of 8 observed UTC dates, so endpoint changes can be read alongside the path taken during the week.

ATM IV · 07-23 to 07-24

2W, -2.08 vol pts

ATM IV · 07-23 to 07-24

1W, -1.83 vol pts

ATM IV · 07-24 to 07-25

1W, +1.81 vol pts

RR25 · 07-24 to 07-25

1W, -1.69 vol pts

RR25 · 07-24 to 07-25

2W, -1.58 vol pts

ATM IV · 07-24 to 07-25

2W, +1.28 vol pts

Tenor	ATM IV low	ATM IV high	ATM IV range	RR25 range	BF25 range
1W	34.18%	36.21%	2.03 vol pts	3.49 vol pts	0.56 vol pts
2W	34.24%	36.32%	2.08 vol pts	3.66 vol pts	0.43 vol pts
1M	34.81%	36.03%	1.22 vol pts	2.93 vol pts	0.22 vol pts
3M	37.91%	38.70%	0.79 vol pts	0.88 vol pts	0.11 vol pts
6M	40.39%	40.84%	0.45 vol pts	0.49 vol pts	0.14 vol pts
9M	41.51%	41.85%	0.34 vol pts	0.52 vol pts	0.20 vol pts
1Y	42.27%	42.61%	0.34 vol pts	0.84 vol pts	0.25 vol pts

08 · Skew and convexity

RR25 and BF25 over the seven-day window.

RR25 moved towards puts, averaging -1.71 volatility points to -4.47% across the six available headline tenors. The largest eligible RR25 movement was at 2W. Negative RR25 denotes a richer put wing.

Tenor	Week end (vol %)	Week start (vol %)	Change (vol pts)
1W	-3.65	0.04	-3.69 vol pts
2W	-4.70	-0.96	-3.74 vol pts
1M	-5.36	-2.28	-3.08 vol pts
3M	-4.77	-4.09	-0.68 vol pts
6M	-4.43	-4.61	+0.18 vol pts
9M	-4.26	-4.67	+0.41 vol pts
1Y	-3.89	-4.61	+0.72 vol pts

BF25 increased, averaging +0.14 volatility points to 2.53% across the six available headline tenors. The largest eligible BF25 movement was at 1W.

Tenor	Week end (vol %)	Week start (vol %)	Change (vol pts)
1W	2.33	1.78	+0.55 vol pts
2W	2.36	2.00	+0.36 vol pts
1M	2.46	2.46	0.00 vol pts
3M	2.67	2.75	-0.08 vol pts
6M	2.71	2.77	-0.06 vol pts
9M	2.68	2.69	-0.01 vol pts
1Y	2.63	2.57	+0.06 vol pts

09 · Listed expiries

Common exchange maturities at both weekly endpoints.

Expiry	Time left	Forward end (USD)	Forward change (USD)	ATM IV end	ATM IV change	RR25 change	BF25 change
31JUL26	2.4 days	63,977.12	-2444.34 USD	38.53%	+2.87 vol pts	-2.74 vol pts	+0.32 vol pts
7AUG26	9.4 days	64,028.88	-2448.99 USD	35.11%	-0.10 vol pts	-2.37 vol pts	+0.33 vol pts
28AUG26	30.4 days	64,184.58	-2454.10 USD	34.83%	-0.20 vol pts	-2.84 vol pts	-0.08 vol pts
25SEP26	58.4 days	64,396.33	-2458.83 USD	36.11%	+0.31 vol pts	-1.74 vol pts	-0.06 vol pts
25DEC26	149.4 days	65,038.8	-2491.12 USD	39.76%	-0.45 vol pts	+0.16 vol pts	-0.10 vol pts
26MAR27	240.4 days	65,689.51	-2554.73 USD	41.09%	-0.33 vol pts	+0.22 vol pts	-0.04 vol pts
25JUN27	331.4 days	66,340.41	-2605.19 USD	42.06%	-0.31 vol pts	+0.62 vol pts	+0.04 vol pts

10 · Smile movement

Reconstructed SVI smiles for common expiries.

Each overlay compares the fitted smile at the two weekly endpoints. Ultra-short expiries remain visible but do not determine headline rankings.

31JUL26rotation towards puts · wing steepening

7AUG26rotation towards puts · wing steepening

28AUG26rotation towards puts

25SEP26rotation towards puts

25DEC26parallel shift lower

26MAR27parallel shift lower

25JUN27parallel shift lower

Weekly surface movement heatmap

Each cell is the fitted IV change in volatility points from week start to week end.

31JUL26

7AUG26

28AUG26

25SEP26

25DEC26

26MAR27

25JUN27

-0.30kATM+0.30k

11 · SVI diagnostics

Weekly movement in a, b, rho, m and sigma.

Parameter changes are shown directly from the stored endpoint fits; no causal interpretation is attached.

Expiry	Δ a	Δ b	Δ rho	Δ m	Δ sigma	Smile classification
31JUL26	+0.01000	-0.01050	+0.10020	+0.08280	-0.05660	rotation towards puts, wing steepening
7AUG26	+0.01920	-0.01010	+0.11240	+0.07800	-0.10800	rotation towards puts, wing steepening
28AUG26	+0.00720	-0.01040	+0.11170	+0.09390	-0.03120	rotation towards puts
25SEP26	+0.00370	-0.01220	+0.09780	+0.09530	-0.00470	rotation towards puts
25DEC26	-0.03010	+0.01330	+0.00560	-0.02770	+0.05570	parallel shift lower
26MAR27	-0.00900	-0.03220	+0.09760	+0.10990	+0.03860	parallel shift lower
25JUN27	+0.03350	-0.07820	+0.14550	+0.22040	-0.02030	parallel shift lower

12 · Methodology and provenance

Generated from validated surface data and stored reporting evidence.

Week-end snapshot: 28 Jul 2026, 21:51 UTC
Week-opening snapshot: 21 Jul 2026, 21:51 UTC
Comparison: Nearest successful surface snapshots approximately seven days apart
Source: Derivasys proprietary historical SVI surface database
Snapshot selection: The final successful BTC surface on each observed UTC date is included. This report contains 8 daily snapshots; an approximately seven-day window contains eight observations when both the start and end dates are present.
Daily report inputs: Unavailable
Calculations and commentary: Metrics and takeaways are deterministic. Daily headlines and introductions may be model-assisted, constrained to the same stored facts; weekly prose is deterministic.
RR convention: 25-delta call IV minus 25-delta put IV
BF convention: Average 25-delta wing IV minus ATM forward IV
Fixed tenors: Fixed-tenor measures are interpolated independently at 1W, 2W, 1M, 3M, 6M, 9M and 1Y; headline rankings prioritise 1W, 2W, 1M, 3M, 6M and 1Y.
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.
Causal claims: The report describes observed surface changes only and does not infer unsupported market drivers, spot moves, flows or forecasts.

This report contains 8 daily snapshots because both the start and end dates are observed within the approximately seven-day window.

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BTC weekly surface: 2W ATM IV falls 0.36 volatility points

BTC ATM implied-volatility term structure