Belief Volatility
Get volatility history
Belief Volatility history, newest first, clamped to the trailing 90-day window.
Each point carries the headline value, every published tenor, the uncertainty band, and the gate names that flagged. The per-leg panel is omitted here; GET /v1/volatility/{ticker}/latest carries it for the current tick.
meta reports effectiveStart, clamped, and historyMaxDays.
GET
/
v1
/
volatility
/
{ticker}
/
history
curl
curl -s "https://api.beliefsystems.xyz/v1/volatility/MIDVOL/history?limit=500" \
-H "Authorization: Bearer $BELIEF_API_KEY"import os
import requests
resp = requests.get(
"https://api.beliefsystems.xyz/v1/volatility/MIDVOL/history?limit=500",
headers={"Authorization": f"Bearer {os.environ['BELIEF_API_KEY']}"},
timeout=10,
)
resp.raise_for_status()
payload = resp.json()
print(payload["data"])const res = await fetch("https://api.beliefsystems.xyz/v1/volatility/MIDVOL/history?limit=500", {
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);<?php
$curl = curl_init();
curl_setopt_array($curl, [
CURLOPT_URL => "https://api.beliefsystems.xyz/v1/volatility/{ticker}/history",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "GET",
CURLOPT_HTTPHEADER => [
"Authorization: Bearer <token>"
],
]);
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}package main
import (
"fmt"
"net/http"
"io"
)
func main() {
url := "https://api.beliefsystems.xyz/v1/volatility/{ticker}/history"
req, _ := http.NewRequest("GET", url, nil)
req.Header.Add("Authorization", "Bearer <token>")
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))
}HttpResponse<String> response = Unirest.get("https://api.beliefsystems.xyz/v1/volatility/{ticker}/history")
.header("Authorization", "Bearer <token>")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.beliefsystems.xyz/v1/volatility/{ticker}/history")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'
response = http.request(request)
puts response.read_body{
"data": {
"count": 2,
"points": [
{
"anchorFingerprint": "8fbefcee88e9d652648cfd9f28e1feb3ffb8068aa32a4e71304d0a43c282ecb5",
"attrDeltaHeadlinePts": -0.000022,
"bandHiPts": 35.636,
"bandLoPts": 35.4505,
"cfHeadlinePts": 35.9193,
"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.",
"clockVersion": "clock-v1.0",
"compositionVersion": "1",
"devigVersion": "devig-proportional-v1",
"effectiveN": 2.4605,
"fbvRLabel": "remaining uncertainty (to resolution)",
"fbvRPts": 77.0436,
"gateNames": [
"underround_flag"
],
"headlinePts": 35.4977,
"methodologyVersion": "fbv-v1.2",
"publicationState": "published",
"revision": 0,
"status": "flagged",
"t": "2026-08-31T13:59:35.599223",
"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
}
}
},
"tier": {
"1": "historical-clock",
"7": "historical-clock",
"30": "historical-clock",
"R": "budget-implied"
},
"units": "probability points",
"wTilde": 0.7419636
},
{
"anchorFingerprint": "8fbefcee88e9d652648cfd9f28e1feb3ffb8068aa32a4e71304d0a43c282ecb5",
"attrDeltaHeadlinePts": 0.000208,
"bandHiPts": 35.6359,
"bandLoPts": 35.4504,
"cfHeadlinePts": 35.9192,
"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.",
"clockVersion": "clock-v1.0",
"compositionVersion": "1",
"devigVersion": "devig-proportional-v1",
"effectiveN": 2.4605,
"fbvRLabel": "remaining uncertainty (to resolution)",
"fbvRPts": 77.0439,
"gateNames": [
"underround_flag"
],
"headlinePts": 35.4977,
"methodologyVersion": "fbv-v1.2",
"publicationState": "published",
"revision": 0,
"status": "flagged",
"t": "2026-08-31T13:54:35.559124",
"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
}
}
},
"tier": {
"1": "historical-clock",
"7": "historical-clock",
"30": "historical-clock",
"R": "budget-implied"
},
"units": "probability points",
"wTilde": 0.74197023
}
],
"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"
},
"windowStart": "2026-08-06T00:01:51.828235Z"
},
"meta": {
"attribution": "Source: Belief Systems (beliefsystems.xyz)",
"clamped": false,
"effectiveStart": "2026-06-02T14:01:38.530876Z",
"generatedAt": "2026-08-31T14:01:38.550465Z",
"historyMaxDays": 90,
"license": "https://beliefsystems.xyz/license",
"termsUrl": "https://beliefsystems.xyz/terms"
}
}{
"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"
}
}{
"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"
}
}{
"error": {
"code": "invalid_interval",
"docsUrl": "https://docs.beliefsystems.xyz/api-reference/limits#invalid-interval",
"message": "interval must be '1h' or '1d'. Full granularity is part of the licensed feed.",
"requestId": "9f2c1ad4e6b74c0f8a3d5e1b7c904a26"
}
}{
"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"
}
}{
"error": {
"code": "invalid_api_key",
"docsUrl": "<string>",
"message": "<string>",
"requestId": "<string>"
}
}Authorizations
bearerAuthapiKeyAuth
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.
Path Parameters
Ticker, case-insensitive. GET /v1/indices and GET /v1/volatility are the catalogs.
Query Parameters
Maximum points to return, newest first. 1 to 5000.
Required range:
1 <= x <= 5000Include computations that did not clear the publication gates. Off by default: gated values are diagnostic, not published readings.
Window start, ISO 8601. Optional, defaults to the earliest point in the trailing 90-day window. Older starts are clamped.
⌘I
curl
curl -s "https://api.beliefsystems.xyz/v1/volatility/MIDVOL/history?limit=500" \
-H "Authorization: Bearer $BELIEF_API_KEY"import os
import requests
resp = requests.get(
"https://api.beliefsystems.xyz/v1/volatility/MIDVOL/history?limit=500",
headers={"Authorization": f"Bearer {os.environ['BELIEF_API_KEY']}"},
timeout=10,
)
resp.raise_for_status()
payload = resp.json()
print(payload["data"])const res = await fetch("https://api.beliefsystems.xyz/v1/volatility/MIDVOL/history?limit=500", {
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);<?php
$curl = curl_init();
curl_setopt_array($curl, [
CURLOPT_URL => "https://api.beliefsystems.xyz/v1/volatility/{ticker}/history",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "GET",
CURLOPT_HTTPHEADER => [
"Authorization: Bearer <token>"
],
]);
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}package main
import (
"fmt"
"net/http"
"io"
)
func main() {
url := "https://api.beliefsystems.xyz/v1/volatility/{ticker}/history"
req, _ := http.NewRequest("GET", url, nil)
req.Header.Add("Authorization", "Bearer <token>")
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))
}HttpResponse<String> response = Unirest.get("https://api.beliefsystems.xyz/v1/volatility/{ticker}/history")
.header("Authorization", "Bearer <token>")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.beliefsystems.xyz/v1/volatility/{ticker}/history")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'
response = http.request(request)
puts response.read_body{
"data": {
"count": 2,
"points": [
{
"anchorFingerprint": "8fbefcee88e9d652648cfd9f28e1feb3ffb8068aa32a4e71304d0a43c282ecb5",
"attrDeltaHeadlinePts": -0.000022,
"bandHiPts": 35.636,
"bandLoPts": 35.4505,
"cfHeadlinePts": 35.9193,
"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.",
"clockVersion": "clock-v1.0",
"compositionVersion": "1",
"devigVersion": "devig-proportional-v1",
"effectiveN": 2.4605,
"fbvRLabel": "remaining uncertainty (to resolution)",
"fbvRPts": 77.0436,
"gateNames": [
"underround_flag"
],
"headlinePts": 35.4977,
"methodologyVersion": "fbv-v1.2",
"publicationState": "published",
"revision": 0,
"status": "flagged",
"t": "2026-08-31T13:59:35.599223",
"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
}
}
},
"tier": {
"1": "historical-clock",
"7": "historical-clock",
"30": "historical-clock",
"R": "budget-implied"
},
"units": "probability points",
"wTilde": 0.7419636
},
{
"anchorFingerprint": "8fbefcee88e9d652648cfd9f28e1feb3ffb8068aa32a4e71304d0a43c282ecb5",
"attrDeltaHeadlinePts": 0.000208,
"bandHiPts": 35.6359,
"bandLoPts": 35.4504,
"cfHeadlinePts": 35.9192,
"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.",
"clockVersion": "clock-v1.0",
"compositionVersion": "1",
"devigVersion": "devig-proportional-v1",
"effectiveN": 2.4605,
"fbvRLabel": "remaining uncertainty (to resolution)",
"fbvRPts": 77.0439,
"gateNames": [
"underround_flag"
],
"headlinePts": 35.4977,
"methodologyVersion": "fbv-v1.2",
"publicationState": "published",
"revision": 0,
"status": "flagged",
"t": "2026-08-31T13:54:35.559124",
"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
}
}
},
"tier": {
"1": "historical-clock",
"7": "historical-clock",
"30": "historical-clock",
"R": "budget-implied"
},
"units": "probability points",
"wTilde": 0.74197023
}
],
"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"
},
"windowStart": "2026-08-06T00:01:51.828235Z"
},
"meta": {
"attribution": "Source: Belief Systems (beliefsystems.xyz)",
"clamped": false,
"effectiveStart": "2026-06-02T14:01:38.530876Z",
"generatedAt": "2026-08-31T14:01:38.550465Z",
"historyMaxDays": 90,
"license": "https://beliefsystems.xyz/license",
"termsUrl": "https://beliefsystems.xyz/terms"
}
}{
"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"
}
}{
"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"
}
}{
"error": {
"code": "invalid_interval",
"docsUrl": "https://docs.beliefsystems.xyz/api-reference/limits#invalid-interval",
"message": "interval must be '1h' or '1d'. Full granularity is part of the licensed feed.",
"requestId": "9f2c1ad4e6b74c0f8a3d5e1b7c904a26"
}
}{
"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"
}
}{
"error": {
"code": "invalid_api_key",
"docsUrl": "<string>",
"message": "<string>",
"requestId": "<string>"
}
}