> ## Documentation Index > Fetch the complete documentation index at: https://docs.beliefsystems.xyz/llms.txt > Use this file to discover all available pages before exploring further. # Get latest volatility > The latest computation for a Belief Volatility series, with the series definition alongside it. `tick.headlinePts` is the headline value in probability points, at `tick.headlineTenorDays`. Never quote it without the tenor: a 30-day and a 1-day reading are different measurements, and both are in `tick.tenors`. A `status` of `flagged` still publishes. The flag is the disclosure, and `tick.gateFlags` states in plain language what flagged. `suspended` means the value did not clear its gates and was withheld. This endpoint returns the same envelope as the public volatility surface, so a value quoted from the API, the website, or the MCP server always matches. ## OpenAPI ````yaml /api-reference/openapi.json get /v1/volatility/{ticker}/latest openapi: 3.1.0 info: contact: name: Belief Systems url: https://beliefsystems.xyz/data description: >- Rules-based benchmark data for prediction markets: Belief index levels and Belief Volatility series, read over HTTPS with an API key. The API is read-only. Every endpoint is a `GET`, every successful response is `{ data, meta }`, and every failure is a single `error` object with a stable `code`. Keys are free and take about a minute to mint at https://beliefsystems.xyz/data. Attribution is required on anything you publish from this data: "Source: Belief Systems (beliefsystems.xyz)". Production, redistribution, and commercial use require a license (https://beliefsystems.xyz/license). license: name: Belief Systems Data License url: https://beliefsystems.xyz/license termsOfService: https://beliefsystems.xyz/terms title: Belief Systems Data API version: '1.0' servers: - description: Production. There is no separate test host; the API is read-only. url: https://api.beliefsystems.xyz security: - bearerAuth: [] - apiKeyAuth: [] tags: - description: >- Belief indices are rules-based benchmarks of how prediction markets price a defined set of events. Levels are exact decimal strings based at 100 on the index's inception date. name: Indices - description: >- Belief Volatility measures how much prediction-market probabilities are expected to move over a stated horizon, in probability points. Always name the tenor when quoting a value. name: Belief Volatility - description: >- The service index, which reports your key's live quota, and pointers to the free point-in-time snapshot bundles. name: Service paths: /v1/volatility/{ticker}/latest: get: tags: - Belief Volatility summary: Get latest volatility description: >- The latest computation for a Belief Volatility series, with the series definition alongside it. `tick.headlinePts` is the headline value in probability points, at `tick.headlineTenorDays`. Never quote it without the tenor: a 30-day and a 1-day reading are different measurements, and both are in `tick.tenors`. A `status` of `flagged` still publishes. The flag is the disclosure, and `tick.gateFlags` states in plain language what flagged. `suspended` means the value did not clear its gates and was withheld. This endpoint returns the same envelope as the public volatility surface, so a value quoted from the API, the website, or the MCP server always matches. operationId: getVolatilityLatest parameters: - description: >- Ticker, case-insensitive. `GET /v1/indices` and `GET /v1/volatility` are the catalogs. example: MIDVOL in: path name: ticker required: true schema: type: string responses: '200': content: application/json: example: data: publicationState: published published: null series: category: elections definitionLine: >- Belief Volatility is a standardized estimate of how much prediction-market probabilities are expected to move over a stated horizon. description: >- How much the 2026 U.S. midterms balance-of-power distribution is expected to move. gates: arbMinDepthUsd: 500 arbToleranceMin: 0.01 arbToleranceTicks: 1 depthFloorUsd: 500 devigTolerance: 0.000001 identityTolerance: 0.000001 impactBudgetPts: 1 overroundFlagHi: 1.04 overroundFlagLo: 0.995 pythagoreanTolerancePts2: 0.01 retireAfterDegradedTicks: 12 snapshotMaxAgeSeconds: 900 snapshotMaxSkewSeconds: 300 spreadToMidMax: 0.5 suspendFailingBudgetShare: 0.1 headlineTenorDays: 30 inceptionAt: '2026-08-06T00:01:51.828235Z' listed: true methodologyUrl: https://docs.beliefsystems.xyz/volatility/methodology name: Midterms Uncertainty Index productFamily: belief_volatility relatedIndexTickers: - MIDR26 - MIDD26 settlementDate: '2027-01-05' slug: midvol targetType: partition_composite tenorsDays: - 1 - 7 - 30 ticker: MIDVOL units: probability points tick: attrDeltaHeadlinePts: -0.000022 attribution: deltaPts: -0.000022 deltaPts2: -0.001553 gapSeconds: 300 legs: - delta: 0.003465 deltaClock: 0.004082 deltaPrice: -0.000617 gridOrder: 1 label: Senate D · House D legKey: sen_d_house_d - delta: -0.00126 deltaClock: 0.003776 deltaPrice: -0.005036 gridOrder: 3 label: Senate R · House D legKey: sen_r_house_d prevComputedAt: '2026-08-31T13:54:35.559124' reason: null status: ok tenorDays: 30 units: points^2 unitsPts: points bandHiPts: 35.636 bandLoPts: 35.4505 budgetW: 0.59357088 clockVersion: clock-v1.0 components: - books_used: yes+no condition_id: >- 0x16c63b7cc37f012b9f59ee164ec03877914c701d06d48291ae8d6fc08a088b0d days_to_settlement: 126.42 fbv_r_pts: 49.9859 gate_flags: [] grid_order: 1 label: Senate D · House D leg_key: sen_d_house_d observed_at: '2026-08-31T13:54:35.542857' p: 0.511888 passes_depth: true tenor_pts: '1': 4.3806 '7': 11.0975 '30': 23.0309 w: 0.249858678296 - books_used: yes+no condition_id: >- 0x998bc71817b2d76921d1999ce0f3431cfd5945583667a371280ca2b430b0c06e days_to_settlement: 126.42 fbv_r_pts: 48.0743 gate_flags: [] grid_order: 3 label: Senate R · House D leg_key: sen_r_house_d observed_at: '2026-08-31T13:54:35.542857' p: 0.362572 passes_depth: true tenor_pts: '1': 4.2131 '7': 10.6731 '30': 22.1501 w: 0.231113438304 computedAt: '2026-08-31T13:59:35.599223' counterfactual: anchorAt: '2026-08-05T16:55:43.501403' anchorFingerprint: >- 8fbefcee88e9d652648cfd9f28e1feb3ffb8068aa32a4e71304d0a43c282ecb5 clockVersion: clock-v1.0 headlinePts: 35.9193 rPts: 77.9586 tenors: '1': pts: 6.8321 share: 0.00768 '7': pts: 17.3078 share: 0.04929 '30': pts: 35.9193 share: 0.212289 definitionLine: >- Belief Volatility is a standardized estimate of how much prediction-market probabilities are expected to move over a stated horizon. devigVersion: devig-proportional-v1 effectiveN: 2.4605 fbvRLabel: remaining uncertainty (to resolution) fbvRPts: 77.0436 gateFlags: - gate: underround_flag legKey: null publicDetail: >- the pre-de-vig price sum was below the overround tolerance headlinePts: 35.4977 headlineTenorDays: 30 labels: clockHomogeneityDisclosure: >- This value assumes Senate D · House D, Senate D · House R, Senate R · House D, Senate R · House R, Other release variance on a common election-night schedule. A Senate runoff, recount, or certification dispute would concentrate mass in a later window not modelled here; per-leg clocks are not yet separately estimated. composition: leg_keys: - other - sen_d_house_d - sen_d_house_r - sen_r_house_d - sen_r_house_r 'n': 5 version: '1' devigVersion: devig-proportional-v1 tier: '1': historical-clock '7': historical-clock '30': historical-clock R: budget-implied methodologyVersion: fbv-v1.2 publicationState: published revision: 0 seriesId: MIDVOL status: flagged sumRaw: 0.98880748 targetType: partition_composite tenors: '1': pts: 6.7519 share: 0.00768 share_ci: null share_meta: ci_unavailable: true mixture: true '7': pts: 17.1047 share: 0.04929 share_ci: null share_meta: ci_unavailable: true mixture: true '30': pts: 35.4977 share: 0.212289 share_ci: null share_meta: ci_unavailable: true mixture: true units: probability points wTilde: 0.7419636 meta: attribution: 'Source: Belief Systems (beliefsystems.xyz)' generatedAt: '2026-08-31T14:01:38.256801Z' license: https://beliefsystems.xyz/license termsUrl: https://beliefsystems.xyz/terms schema: $ref: '#/components/schemas/VolatilityLatestResponse' description: Success. '401': content: application/json: example: error: code: invalid_api_key docsUrl: >- https://docs.beliefsystems.xyz/api-reference/limits#invalid-api-key message: >- This endpoint requires a Data API key. Create one free at https://beliefsystems.xyz/data ; programmatic or commercial licensing is at https://beliefsystems.xyz/license. requestId: 9f2c1ad4e6b74c0f8a3d5e1b7c904a26 schema: $ref: '#/components/schemas/Error' description: Missing or unresolvable API key. '404': content: application/json: example: error: code: not_found docsUrl: >- https://docs.beliefsystems.xyz/api-reference/limits#not-found message: >- No Belief index 'NOPE'. GET /v1/indices lists the published catalog. requestId: 9f2c1ad4e6b74c0f8a3d5e1b7c904a26 schema: $ref: '#/components/schemas/Error' description: No index or volatility series matches that ticker on this surface. '429': content: application/json: example: error: code: rate_limited docsUrl: >- https://docs.beliefsystems.xyz/api-reference/limits#rate-limited message: 'Rate limit exceeded: 60 requests per minute per key.' requestId: 9f2c1ad4e6b74c0f8a3d5e1b7c904a26 schema: $ref: '#/components/schemas/Error' description: >- Rate limited. Sleep for `Retry-After` seconds, which is exact on both windows. default: content: application/json: schema: $ref: '#/components/schemas/Error' description: Error. Every /v1 failure uses this shape. x-codeSamples: - label: curl lang: curl source: >- curl -s "https://api.beliefsystems.xyz/v1/volatility/MIDVOL/latest" \ -H "Authorization: Bearer $BELIEF_API_KEY" - label: Python lang: python source: |- import os import requests resp = requests.get( "https://api.beliefsystems.xyz/v1/volatility/MIDVOL/latest", headers={"Authorization": f"Bearer {os.environ['BELIEF_API_KEY']}"}, timeout=10, ) resp.raise_for_status() payload = resp.json() print(payload["data"]) - label: JavaScript lang: javascript source: >- const res = await fetch("https://api.beliefsystems.xyz/v1/volatility/MIDVOL/latest", { headers: { Authorization: `Bearer ${process.env.BELIEF_API_KEY}` }, }); if (!res.ok) throw new Error(`Belief Systems API ${res.status}`); const { data, meta } = await res.json(); console.log(data); components: schemas: VolatilityLatestResponse: properties: data: properties: publicationState: description: Publication state of the series surface. example: published type: string published: additionalProperties: true description: >- The most recent value that cleared publication, when it differs from `tick`. Null when `tick` is itself the published value. type: - object - 'null' series: description: >- The series definition. Identical across the catalog, latest, and history endpoints. properties: category: example: elections type: string definitionLine: description: >- The standing definition of Belief Volatility. Quote it when publishing a value. type: string description: description: One line on what the series measures. type: string gates: additionalProperties: true description: >- The publication tolerances in force for this series: overround bounds, depth floors, spread ceilings, and any partition consistency checks. Published so a value can be checked against the gates that admitted it. Field set varies by series target type. See the Belief Volatility methodology for what each gate tests. type: object headlineTenorDays: description: >- The tenor `headlinePts` refers to. Always name the tenor when quoting a value. example: 30 type: integer inceptionAt: format: date-time type: string listed: description: True when the series is published on the public surface. type: boolean methodologyUrl: format: uri type: string name: example: Midterms Uncertainty Index type: string productFamily: example: belief_volatility type: string relatedIndexTickers: description: Belief indices covering the same underlying events. items: type: string type: array settlementDate: description: Backstop settlement date, ISO 8601 date. type: - string - 'null' slug: description: URL segment for this series on beliefsystems.xyz. type: string targetType: description: The structure being measured. example: partition_composite type: string tenorsDays: description: Horizons published for this series, in days. example: - 1 - 7 - 30 items: type: integer type: array ticker: example: MIDVOL type: string units: description: The unit every `pts` value is quoted in. example: probability points type: string type: object tick: description: The most recent computation for this series. properties: attrDeltaHeadlinePts: description: Change in `headlinePts` since the previous tick. type: number attribution: additionalProperties: true description: >- Decomposition of the move since the previous tick into price and clock contributions, per leg. type: object bandHiPts: description: Upper bound of the published uncertainty band. type: number bandLoPts: description: Lower bound of the published uncertainty band. type: number budgetW: description: Raw budget weight. type: number clockVersion: example: clock-v1.0 type: string components: description: >- One entry per leg of the measured structure: its price, weight, per-tenor contribution, and depth-gate result. The example below is abridged to two of five legs for readability. items: additionalProperties: true type: object type: array computedAt: description: >- UTC timestamp with microsecond precision. Serialized WITHOUT a `Z` suffix or offset, unlike timestamps elsewhere on this API. Treat it as UTC and attach the timezone yourself; a strict RFC 3339 parser will reject it. type: string counterfactual: additionalProperties: true description: >- The same value recomputed against the frozen inception anchor, for like-for-like comparison over time. type: object definitionLine: type: string devigVersion: example: devig-proportional-v1 type: string effectiveN: description: Effective number of independent legs behind the value. type: number fbvRLabel: description: The published label for `fbvRPts`. type: string fbvRPts: description: >- Remaining uncertainty from now to resolution, in probability points. type: number gateFlags: description: >- Gates that flagged on this tick. A flagged value still publishes; the flag is the disclosure. items: properties: gate: type: string legKey: type: - string - 'null' publicDetail: description: Plain-language statement of what flagged. type: string type: object type: array headlinePts: description: >- The headline value, in probability points, at `headlineTenorDays`. example: 35.4977 type: number headlineTenorDays: example: 30 type: integer labels: additionalProperties: true description: >- Estimation tiers, composition labels, consistency checks, and standing disclosures for this tick. type: object methodologyVersion: example: fbv-v1.2 type: string publicationState: description: '`published` or `withheld`.' example: published type: string revision: description: Revision of this computation. 0 is the original. type: integer seriesId: example: MIDVOL type: string status: description: >- `ok`, `flagged` (published with a disclosed gate flag), or `suspended`. example: flagged type: string sumRaw: description: Pre-de-vig sum of constituent prices. type: number targetType: type: string tenors: additionalProperties: properties: pts: description: >- Expected movement over this horizon, in probability points. type: number share: description: >- Fraction of remaining uncertainty released by this horizon. type: - number - 'null' share_ci: description: Confidence interval on `share`, when available. items: type: number type: - array - 'null' share_meta: additionalProperties: true description: How `share` was derived. type: object type: object description: >- Published horizons, keyed by tenor in days as a string. `tenors["30"].pts` is the 30-day value, and equals `headlinePts` when 30 is the headline tenor. type: object units: example: probability points type: string wTilde: description: Normalized budget weight. type: number type: object type: object meta: properties: attribution: description: >- The attribution line required on anything you publish from this data. Reproduce it verbatim. example: 'Source: Belief Systems (beliefsystems.xyz)' type: string generatedAt: description: >- When this response was generated. UTC timestamp with microsecond precision, `Z`-suffixed. format: date-time type: string license: description: Terms covering production, redistribution, and commercial use. format: uri type: string termsUrl: description: Terms of Service. format: uri type: string required: - attribution - license - termsUrl - generatedAt type: object required: - data - meta type: object Error: description: >- Every failure replaces `data` and `meta` with a single `error` object. Match on `code`, which is a stable contract. `message` is written for a person and may be reworded. properties: error: properties: code: description: Stable machine-readable error code. enum: - invalid_api_key - ip_rate_limited - rate_limited - daily_limit_reached - not_found - invalid_parameter - invalid_interval - invalid_window - method_not_allowed - internal_error - unavailable - error type: string docsUrl: description: Deep link to this code on the limits and errors page. format: uri type: string message: description: Human-readable explanation. Not a stable contract. type: string requestId: description: >- Correlation id, also returned as the X-Request-Id header. Quote it in support requests. type: string required: - code - message - docsUrl - requestId type: object required: - error title: Error type: object securitySchemes: bearerAuth: description: >- Your Data API key as a Bearer token: `Authorization: Bearer belief_live_...`. This is the canonical form. Keys belong on a server, never in a browser. scheme: bearer type: http apiKeyAuth: description: >- The same key sent as `X-API-Key` instead. Accepted everywhere the Bearer header is. Send one or the other, not both. in: header name: X-API-Key type: apiKey ````