---
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, required — Most recent ingested SEC quarter (e.g. 2025q4).
    - `latest_date` string, required — Latest trading date covered (YYYY-MM-DD).
    - `symbol_count` integer, required — Number of securities with a rollup.
    - `quarter_count` integer, required — Number of quarters ingested.
    - `count` integer, required — Number of rows in the leaderboard.
    - `leaderboard` MarketStructureLeaderRecord[], required — Latest day's securities by hidden volume descending.
      - `symbol` string, required — Security ticker symbol.
      - `date` string, required — Trading date (YYYY-MM-DD).
      - `trade_volume` integer, required — Total executed share volume.
      - `hidden_volume` integer, required — Executed volume from non-displayed (hidden) orders.
      - `hidden_volume_rate` number, nullable — Hidden volume / trade volume.
      - `odd_lot_volume_rate` number, nullable — Odd-lot volume / trade volume.
      - `cancel_to_trade` number, nullable — Cancellations per trade.
  - `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.
- `429` — Daily rate limit exceeded. Check `X-RateLimit-Reset` for the next window.
- `503` — Upstream source is temporarily unavailable. Retry after a short delay.

---

[API](https://skmtc.net/sugra/apis/sugra-api.md) · [All operations](https://skmtc.net/sugra/apis/sugra-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/sugra/sugra-api/versions/4e2740743eb4/schema)