---
title: "S&P 500 constituents (membership metadata)"
method: GET
path: "/api/v1/equities/sp500/constituents"
tags: ["Equities Indices"]
---

# S&P 500 constituents (membership metadata)

`GET /api/v1/equities/sp500/constituents`

Returns the full S&P 500 constituent list (503 entries) with GICS sector + sub-industry classifications + date-added + SEC EDGAR CIK identifiers. Sourced from public Wikipedia (CC-BY-SA-4.0) membership announcements via daily auto-refresh blob; hardcoded 503-entry snapshot serves as defence-in-depth fallback when the blob is unavailable. Filter by ``?sector=<GICS sector>`` or ``?sub_industry=<GICS sub-industry>`` to narrow the list. Use case: UC-2 Earnings Whiplash Map filters earnings calendar by SPX members; UC-1 Institutional Footprint cross-references CIK to /sec/13f endpoints. The ``data_source`` field exposes whether the response was served from the Wikipedia blob (``blob_wikipedia``) or the hardcoded fallback (``hardcoded_fallback``).

## Query parameters

- `sector` string, nullable — Optional GICS Level 1 sector filter. Case-sensitive. Returns 400 with the canonical 11-sector list when the value is not in the GICS taxonomy.
- `sub_industry` string, nullable — Optional GICS Level 4 sub-industry filter. Case-sensitive. Returns 400 with the observed catalog when the value is not present in the current data source.

## Response `200`

Filtered S&P 500 constituents with provenance.

- EnvelopeSpxConstituentsPayload
  - `data` SpxConstituentsPayload, required — S&P 500 constituents list with curation provenance. v1.1 scope (GAP-3.3 2026-05-23): full 503-entry index list, served from a daily Wikipedia auto-refresh blob with a hardcoded 503-entry snapshot as defence-in-depth fallback. The endpoint never returns fewer than 503 constituents.
    - `constituents` SpxConstituent[], required — Filtered constituent list (alphabetical by ticker for stable ordering).
      - `ticker` string, required — Stock symbol on NYSE / Nasdaq.
      - `name` string, required — Company name as listed in S&P membership announcements.
      - `gics_sector` string, required — GICS Level 1 sector (1 of 11 canonical sectors).
      - `gics_sub_industry` string, required — GICS Level 4 sub-industry classification.
      - `date_added` string, nullable — ISO date the company was added to the S&P 500 index. ``null`` when the upstream Wikipedia row has a non-ISO value (legacy entries with just year or 'unknown'). Codex R1 P3 #2.
      - `cik` string, required — 10-digit zero-padded SEC EDGAR CIK identifier (cross-link to /sec/13f and other EDGAR endpoints).
    - `count` integer, required — Number of constituents returned after filtering.
    - `as_of_date` string, required — ISO date of the snapshot underpinning this response (blob fetch date or hardcoded curation timestamp).
    - `data_source` string, required — Provenance of the data in this response. ``blob_wikipedia`` means the daily Wikipedia auto-refresh blob was served. ``hardcoded_fallback`` means the blob was missing or unreadable and the static 503-entry snapshot was served instead.
    - `parse_status` string, nullable — Parse status echoed from the ingest blob (``ok`` or ``partial_parse``). ``null`` when the response was served from the hardcoded fallback path (no blob involved).
    - `methodology` string, required — Plain-English description of curation source and refresh cadence.
    - `license_attribution` string, required — Provenance and license string. S&P 500 list curated from public Wikipedia source (CC-BY-SA-4.0); Wikipedia content reflects S&P Dow Jones Indices LLC public membership announcements.
  - `meta` SugraMeta, required — Metadata on a /api/v1/* response envelope built through `helpers.response.sugra_response`, which is how routes are expected to answer. A route that assembles its own `meta` dict carries only the keys it writes itself, so an optional field below can be absent because this response has nothing to report OR because that route does not build its envelope here - the two are not distinguishable from the outside (API-43).
    - `endpoint` string, required — Requested endpoint path.
    - `data_time` string, required — ISO 8601 timestamp the data on this response is stamped with. It is the source's own timestamp whenever the source supplied one this API could read; when it did not, this field falls back to the value of `response_time` and `data_age_days` is omitted, so the PRESENCE of that field is the signal to read - with the one exception named in its own description, a route that substitutes its own current time for a source timestamp it never received. Usually UTC (`Z`), but a source stating its own numeric offset keeps it (2026-04-16T14:30:00+09:00) rather than being converted a second time. For a source that publishes by period this is the period's START (see `period`) and for one that publishes by calendar day it is that day's midnight - in neither case a moment at which anything was observed or released.
    - `response_time` string, required — ISO 8601 UTC timestamp when this response was produced.
    - `provider` string, required — API name and version.
    - `data_age_days` number, nullable — Age of the data in days at the moment this response was produced, i.e. `response_time` minus `data_time`. Present ONLY when the timestamp this response is stamped with is a clock time that could be read as a real instant. It is ABSENT - never 0 - in every other case. Absent when no readable source timestamp was supplied, because `data_time` then repeats `response_time` and a zero age would assert that the data is current precisely where its true age is unknown. Absent when the source names a calendar day, a month, a quarter or a year (see `period`): the instant is then a boundary this API anchored at midnight, and time since a day or a quarter BEGAN is a different quantity from the age of the data - a daily series is out by up to a day, a quarterly one by up to a quarter. A midnight counts as such a boundary whichever zone it is stated in, and whether the source stated it or this API anchored it. The one case this field cannot see is a route that substitutes its own current time for a source timestamp it never received: the substituted value is a real, readable instant and is indistinguishable from one the source stated, so the age reads as roughly 0. The shared cache-and-fetch helper behind most routes stopped doing that (API-43), but the presence of this field is a statement about the timestamp the response carries, not a guarantee about the route that supplied it. Rounded to 0.001 day (86.4 seconds), so 0.0 is a real measured age anywhere within roughly +/-43 seconds and not a stand-in for unknown; a source stamping an instant in the future reports a negative value (-0.001 or less) rather than being clamped. Sources publish on very different cadences, so a non-zero age is normal, not an error. Preserve absence in client code: a generated client that materialises a missing optional number as its numeric default turns 'age unknown' back into 'age zero', which is the exact confusion this field exists to remove.
    - `source` string, nullable — Identifier of the primary upstream source used for this response.
    - `attribution` string, nullable — Human-readable attribution mandated by an upstream source (e.g. a securities regulator or self-regulatory organization). Present only on responses whose source requires the owner and source to be clearly identified. Do not remove or alter it when using the response.
    - `fallback_used` boolean, nullable — True when the primary source failed and a fallback produced the data.
    - `fallback_chain` string[], nullable — Ordered list of sources attempted, in the order they were tried.
    - `cached` boolean, nullable — True when this response was served from the internal cache.
    - `stale` boolean, nullable — True when the cached response was returned after the upstream rate-limited or errored. Clients can use this to detect degraded data.
    - `period` string, nullable — Unit of observation, when the source publishes by period rather than by instant. `data_time` carries the period's START instant so it stays machine-readable; this field preserves what that instant used to mean, which the conversion would otherwise erase. Present only for such sources, and only when the source hands the API the label itself - a client that converts the period to its start instant before building the envelope loses the label, though not the age exclusion, which is decided by the instant. Note that `data_age_days` is omitted whenever this is present, because an age measured from a period start is not a freshness figure.
    - `notes` string, nullable — Data-quality caveat about THIS response - how old the underlying report is, a chokepoint AIS lower-bound, or that a source-reported `data_time` could not be read and the response time is shown instead. Distinct from `attribution`, which is a licensing obligation. Multiple caveats are joined with ' | '. Present only when there is one.

## Other responses

- `401` — Missing or invalid `x-api-key` header. JSON body with a stable `code` distinguishing `missing_api_key` (no header sent) from `invalid_api_key` (header sent, key not accepted); any other 401 source carries the generic `unauthorized` with its detail as `reason`. Plus `hint`. `plan` is always null on 401 - an unauthenticated request has no plan; quota exhaustion is 429, not 401.
- `422` — Validation Error
- `429` — Daily rate limit exceeded. Check `X-RateLimit-Reset` for the next window.
- `503` — Upstream source is temporarily unavailable. Retry after a short delay.

## Changes

- **2026-09-01** `328d061c12ca` — 3 info
  - added the optional property `meta/data_age_days` to the response with the `200` status
  - added the optional property `meta/notes` to the response with the `200` status
  - added the optional property `meta/period` to the response with the `200` status
- **2026-08-08** `4c4530760ba1` — 12 info
  - added the optional property `code` to the response with the `401` status
  - added the optional property `code` to the response with the `429` status
  - added the optional property `code` to the response with the `503` status
  - added the optional property `hint` to the response with the `401` status
  - …8 more

[Change history](https://skmtc.dev/sugra/apis/sugra-api/changes/api/v1/equities/sp500/constituents/get.md)

---

[API](https://skmtc.dev/sugra/apis/sugra-api.md) · [All operations](https://skmtc.dev/sugra/apis/sugra-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/sugra/sugra-api/revisions/68953d8a221b/schema)