{"schemaVersion":1,"asset":"BTC","reportDate":"2026-09-21","timestamps":{"currentSnapshotAt":"2026-09-21T18:42:00+00:00","previousSnapshotAt":"2026-09-20T18:42:00+00:00","generatedAt":"2026-09-21T18:42:59+00:00"},"comparison":{"status":"available","note":null},"provenance":{"reportArtifact":"published daily report","sourceReport":"BTC","sourceReportHref":"/reports/2026-09-21","source":"Derivasys proprietary historical SVI surface database","comparison":"Nearest successful surface snapshots approximately 24 hours apart","rrConvention":"25-delta call IV minus 25-delta put IV","bfConvention":"Average 25-delta wing IV minus ATM forward IV","fixedTenors":"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.","realisedVolatility":null},"tenors":[{"tenor":"1W","targetExpiry":1790620920052,"availability":"available","unavailableReason":null,"atmIv":{"current":38.96,"previous":34.2,"change":4.76,"percentChange":13.92},"rr25":{"current":-0.22,"previous":-0.61,"change":0.39,"percentChange":63.93},"bf25":{"current":2.22,"previous":1.83,"change":0.39,"percentChange":21.31}},{"tenor":"2W","targetExpiry":1791225720052,"availability":"available","unavailableReason":null,"atmIv":{"current":37.49,"previous":33.83,"change":3.66,"percentChange":10.82},"rr25":{"current":0.23,"previous":-0.45,"change":0.68,"percentChange":151.11},"bf25":{"current":2.21,"previous":1.75,"change":0.46,"percentChange":26.29}},{"tenor":"1M","targetExpiry":1792608120052,"availability":"available","unavailableReason":null,"atmIv":{"current":36.3,"previous":34.09,"change":2.21,"percentChange":6.48},"rr25":{"current":-0.56,"previous":-1.22,"change":0.66,"percentChange":54.1},"bf25":{"current":2.18,"previous":1.8,"change":0.38,"percentChange":21.11}},{"tenor":"3M","targetExpiry":1797878520052,"availability":"available","unavailableReason":null,"atmIv":{"current":38.66,"previous":36.98,"change":1.68,"percentChange":4.54},"rr25":{"current":-0.46,"previous":-1.59,"change":1.13,"percentChange":71.07},"bf25":{"current":2.2,"previous":2.03,"change":0.17,"percentChange":8.37}},{"tenor":"6M","targetExpiry":1805740920052,"availability":"available","unavailableReason":null,"atmIv":{"current":39.46,"previous":38.53,"change":0.93,"percentChange":2.41},"rr25":{"current":-0.46,"previous":-0.88,"change":0.42,"percentChange":47.73},"bf25":{"current":2.48,"previous":2.42,"change":0.06,"percentChange":2.48}},{"tenor":"9M","targetExpiry":1813603320052,"availability":"available","unavailableReason":null,"atmIv":{"current":40.37,"previous":39.64,"change":0.73,"percentChange":1.84},"rr25":{"current":-0.28,"previous":-0.73,"change":0.45,"percentChange":61.64},"bf25":{"current":2.56,"previous":2.49,"change":0.07,"percentChange":2.81}},{"tenor":"1Y","targetExpiry":1821552120052,"availability":"unavailable","unavailableReason":"The target tenor falls outside the listed-expiry range at one or both snapshots; extrapolated values are suppressed.","atmIv":{"current":null,"previous":null,"change":null,"percentChange":null},"rr25":{"current":null,"previous":null,"change":null,"percentChange":null},"bf25":{"current":null,"previous":null,"change":null,"percentChange":null}}],"realisedVolatility":null,"realisedVolatilityUnavailableReason":"Canonical BTC index coverage for 24h is incomplete: expected 1440 one-minute returns, found 1211 (84.0972% coverage); returns spanning missing minutes are excluded"}