Stock ownership
List a stock's reported rows by position type and follow aggregate exposure across quarters. The legacy total combines common-share, option-notional and any tracked principal-denominated quantities, so it is not pure ownership.
SEC Form 13F · REST API · MCP
Institutional holdings API for SEC 13F data
Query reported common-share ownership, the tracked positions an institution disclosed and how those positions changed between quarters. Use the REST API in your application, or bring the same primary-source holdings data into ChatGPT, Claude and other AI clients through MCP.
Free: 100 requests a day, no credit card. One account works with REST and MCP.
From one stock to the full 13F market
The API exposes the same normalized filing history used by the Equibles institution and stock pages.
Institution portfolios
Retrieve a filer's tracked U.S.-listed common-stock, principal-denominated and related put/call positions, concentration, sector allocation and quarter-over-quarter changes.
Market-wide activity
Rank the most widely held stocks, aggregate quarterly activity, and compare consensus positions across selected institutions.
Purpose-built 13F endpoints
Use the ticker routes for company ownership, CIK routes for a specific filer, and market routes for cross-filer analysis.
View parameters and responsesGET /v1/stocks/{ticker}/institutional-holdersGET /v1/stocks/{ticker}/institutional-ownershipGET /v1/institutions/{cik}/portfolioGET /v1/13f/market-activityGET /v1/consensus-holdings
Read the filing period correctly
Form 13F reports quarter-end positions rather than live trades. Managers generally file within 45 days after quarter-end, so a filing reveals a historical snapshot, not today's portfolio.
For stock-ownership and market-wide endpoints, an open filing window is labeled as a combined view and carries the prior-quarter position for a manager that has not filed yet. Institution-specific endpoints return that filer's latest actual report date unless you request another available date.
Source: SEC Form 13F data sets.
What the API preserves
- The filer name, SEC CIK and report date behind each position
- Rows distinguish common shares, principal-denominated securities, puts and calls; aggregate history is reported exposure, not pure ownership
- Position value normally derived from shares × report-date close, with filed value as a fallback; zero can mean unavailable
- Coverage and filing-window context needed to interpret quarter changes
- Pagination and explicit identifiers for reproducible downstream analysis
Use the data in code, AI, or the browser
Choose the interface that fits the work; all three surfaces read the same institutional-holdings store.
Frequently asked questions
What is a 13F institutional holdings API?
It turns public SEC Form 13F filings into structured endpoints for querying stock ownership, institution portfolios and changes between reported quarters.
How fresh is 13F holdings data?
Form 13F is quarterly and generally due within 45 days after quarter-end. Stock-ownership and market-wide endpoints label an open filing window and distinguish carried prior-quarter positions; institution-specific endpoints return the filer's latest actual report date.
Does Form 13F show every asset or trade?
No. Form 13F reports covered quarter-end positions, not a complete live portfolio or individual trade history. Equibles tracks U.S.-listed common stocks, principal-denominated securities and related puts and calls. Rows identify common, principal, put and call types, but aggregate history sums their reported quantities and is not pure ownership; preferred shares, bonds, warrants and untracked share classes may be absent.
Can I use the same holdings data in ChatGPT or Claude?
Yes. The Equibles MCP server exposes institutional-holdings tools to connected AI clients, while the REST API provides the same data for code and applications.
Is there a free institutional holdings API?
Yes. The Equibles free tier includes 100 requests a day, shared across the REST API and MCP server, with no credit card. Paid plans raise the limit.
Start querying institutional holdings.
One free key for stock ownership, institution portfolios and market-wide 13F activity.