# ko.io

> The clean record of who owns what in U.S. markets: SEC disclosures parsed
> into structured data; 13F holdings reconciled against filing totals, with
> detected unit errors corrected. Queryable for investors and AI agents: 13F institutional holdings, insider (Form 3/4/5)
> filings, congress (STOCK Act) trading, fails-to-deliver, fundamentals and
> macro indicators, served in the Terminal, via REST API and an MCP server.
> SEC data is parsed from public filings; filing lookup endpoints locate the
> source documents (13F and Form 4 REST rows do not carry accession numbers yet).

Languages: the site is English at https://ko.io/ and Simplified Chinese under
https://ko.io/zh/ (every page exists in both; hreflang alternates link them).
The API (base URL `https://api.ko.io/api/v1`, documented at https://ko.io/docs/) and the MCP server (https://mcp.ko.io/mcp) return
English field names.

Scale (measured 2026-09-25 on the production database, one copy): 5.9M+ SEC
filings parsed into tables (distinct accession numbers, excluding XBRL-only
references); 18.7M+ EDGAR filings indexed since 1994 (indexed, not parsed);
88M+ 13F position records across 53 quarters, 2013Q2 to present (records, not
trades); 20 years of insider filings (Forms 3/4/5 since 2006); congress STOCK
Act disclosures; XBRL fundamentals; Treasury / Fed / BLS / EIA / CFTC / FDIC
macro series.

## Data quality

- 13F unit corrections: 11,587 of 311,477 selected 13F filings reported values
  in the wrong unit (dollars vs thousands, a 1,000x error) and are corrected by
  a detector; the as-filed values are kept.
- 13F reconciliation: 305,479 institution-quarters checked against each
  filing's own cover-page entry count and total value; 300,209 published and
  5,270 quarantined with a reason code (totals that don't reconcile, ambiguous
  filing selection, duplicate within a manager family, missing cover totals).
- 400+ automated data tests are defined in the pipeline (an inventory, not a
  per-release count). 13F serving tables are published only when their
  required tests pass; otherwise the last good release keeps serving.
- Other datasets are tested but not reconciled this way.
- Planned, not available today: ko.io-signed releases and release-specific AI sample-review receipts.

## API

- [API documentation](https://ko.io/docs/): guide, authentication, limits and error codes (Chinese: https://ko.io/zh/docs/). Base URL `https://api.ko.io/api/v1`. Authenticate with 'Authorization: Bearer ko_live_...'. Use ?demo=true on Free-plan endpoints for keyless access (about 1,000 requests an hour per IP); Pro and Builder endpoints return 403 PLAN_REQUIRED. Plans: Free (latest period), Pro $60/month or $600/year VAT included (full history), Builder on request (bulk export): https://ko.io/pricing/.
- [Quickstart](https://ko.io/docs/quickstart/): a first call in curl, Python or MCP.
- [API reference](https://ko.io/docs/api/): every endpoint with parameters and example responses.
- [OpenAPI spec](https://ko.io/openapi.yaml): machine-readable API schema.
- [Data reference](https://ko.io/datasets/): every dataset with fields, coverage, and example payloads.
- [Pricing](https://ko.io/pricing/): free and paid tiers.

## MCP server

- [MCP setup](https://ko.io/mcp/): connect Claude, Cursor, or any MCP client to https://mcp.ko.io/mcp (Streamable HTTP, 24 tools: list_institutions, get_institution_holdings, get_stock_profile, get_stock_holders, get_stock_activity, get_stock_price, get_stock_financials, get_insider_trades, list_insider_traders, get_congress_trades, get_congress_member, get_crypto_exposure, get_crypto_holders, get_crypto_holder, sec_list_filings, sec_get_filing_index, sec_get_filing_document, get_ftd_data, get_form144_notices, search, get_treasury_yields, get_fed_rates, get_economic_indicators, get_financial_stress).

## Data pages

Entity URL patterns (rendering and data availability vary by page):

- Stocks: https://ko.io/stock/{TICKER}/ (institutional holders, e.g. /stock/AAPL/)
- Institutions: https://ko.io/institution/{slug}/ (13F portfolio, e.g. /institution/berkshire-hathaway-inc-1067983/)
- Investment managers (people): https://ko.io/manager/{slug}/ (a named manager's 13F portfolio across every filing entity they run, e.g. /manager/seth-klarman/, /manager/bill-ackman/). Curated set of well-known managers; API directory at https://api.ko.io/api/v1/people?demo=true.
- Insider activity by company: https://ko.io/executive/{TICKER}/
- Insider by person: https://ko.io/insider/{CIK}/
- Congress members: https://ko.io/congress/{member-slug}/ (e.g. /congress/nancy-pelosi/)
- [A-Z directory of all pages](https://ko.io/browse/)

## Research

- [ko.io Research](https://kosearch.substack.com/): 13F flow analysis and hands-on tutorials for building AI agents on SEC data.

## Attribution

Data may be cited with a link to the source page on ko.io. All datasets are
derived from public SEC EDGAR and U.S. federal sources; ko.io adds parsing,
unit correction and reconciliation (13F), and entity resolution.