---
title: "Market-structure leaderboard (latest SEC day)"
method: GET
path: "/api/v1/market-structure"
tags: ["Finance"]
---

# Market-structure leaderboard (latest SEC day)

`GET /api/v1/market-structure`

Securities with the most non-displayed (hidden) executed volume on the most recent SEC market-structure day. SEC Market Structure (MIDAS) metrics describe how a security trades on the lit exchanges, aggregated across venues per day: hidden_volume_rate is the share of executed volume that came from non-displayed (hidden) orders - a dark-liquidity-within-lit signal; odd_lot_volume_rate, cancel_to_trade (order cancellation pressure), trade_to_order_rate (fill efficiency) and avg_trade_size round out the picture, with mcap / turnover / volatility / price deciles (1-10). Off-exchange (ATS / dark-pool) venue volume is NOT in this dataset - it covers lit exchanges only. Source: U.S. Securities and Exchange Commission.

## Response `200`

Latest-day hidden-volume leaderboard + coverage.

- EnvelopeMarketStructureMarketData
  - `data` MarketStructureMarketData, required
    - `latest_quarter` string, nullable — Most recent ingested SEC quarter (e.g. 2025q4).
    - `latest_date` string, nullable — Latest trading date covered (YYYY-MM-DD).
    - `symbol_count` union — Number of securities with a rollup.
      - integer
      - number
    - `quarter_count` union — Number of quarters ingested.
      - integer
      - number
    - `count` union — Number of rows in the leaderboard.
      - integer
      - number
    - `leaderboard` MarketStructureLeaderRecord[], nullable — Latest day's securities by hidden volume descending.
      - `symbol` string, nullable — Security ticker symbol.
      - `date` string, nullable — Trading date (YYYY-MM-DD).
      - `trade_volume` union — Total executed share volume.
        - integer
        - number
      - `hidden_volume` union — Executed volume from non-displayed (hidden) orders.
        - integer
        - number
      - `hidden_volume_rate` union — Hidden volume / trade volume.
        - integer
        - number
      - `odd_lot_volume_rate` union — Odd-lot volume / trade volume.
        - integer
        - number
      - `cancel_to_trade` union — Cancellations per trade.
        - integer
        - number
  - `meta` SugraMeta, required — Metadata attached to every /api/v1/* response envelope.
    - `endpoint` string, required — Requested endpoint path.
    - `data_time` string, required — ISO 8601 UTC timestamp of the source data, not of the request.
    - `response_time` string, required — ISO 8601 UTC timestamp when this response was produced.
    - `provider` string, required — API name and version.
    - `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.

## 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.
- `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

- **2026-08-28** `560e8847c7b3` — 12 breaking
  - the response property `data/count` became optional for the status `200`
  - the response property `data/latest_date` became optional for the status `200`
  - the response property `data/latest_quarter` became optional for the status `200`
  - the response property `data/leaderboard` became optional for the status `200`
  - …8 more
- **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/market-structure/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/87582f2e0110/schema)