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Institutional investors file Form 13F on a delayed schedule. The useful question is usually not simply what a manager owns, but what changed between its two most recent disclosed reports. SEC API compares the latest two parsable 13F reports for a manager CIK and returns a row-level position diff alongside the source record for the current report.

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Capabilities

Latest disclosed-report diff

Compare the latest two parsable 13F reports for one manager CIK. Each position is classified as added, removed, changed, or unchanged.

Share and value changes

Inspect current and prior shares and value, with absolute deltas for positions that changed.

Filing provenance

Keep the current filing accession, source URL, filing date, and request metadata with the comparison output.

Bounded position output

Set a position limit when you need a concise comparison; use the underlying reports when a full filing review is required.

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Quick start

Compare a manager’s two most recent parsable disclosed reports: 
curl -X POST "https://api.secapi.ai/v1/owners/13f/compare" \
  -H "x-api-key: $SECAPI_API_KEY" \
  -H "content-type: application/json" \
  -d '{"cik":"0001350694","limit":50}'

{
  "managerName": "Example Manager",
  "currentFilingDate": "2025-02-14",
  "previousFilingDate": "2024-11-14",
  "rows": [
    {
      "issuer": "Example Issuer",
      "cusip": "000000000",
      "status": "changed",
      "currentValueUsdThousands": 1200,
      "previousValueUsdThousands": 900,
      "deltaValueUsdThousands": 300,
      "currentShares": 10000,
      "previousShares": 8000,
      "deltaShares": 2000
    }
  ]
}
The route selects the latest two parsable reports. It does not accept arbitrary reporting periods. For a period-specific report, retrieve the underlying 13F filing first and retain both the filing date and the report date in your research record.

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Use cases

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Smart money tracking

Monitor how a selected manager’s disclosed positions changed from one report to the next. Treat the result as a delayed disclosure signal, not a view of its current book.

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Crowded trade detection

Use the row-level diff to identify positions worth investigating, then compare the issuer’s filings, valuation, and other managers separately.

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Portfolio rebalancing signals

Use disclosed changes as one input to a research process. Shares and reported value may move for reasons other than a discretionary buy or sell.

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Client reporting

Create a reviewed report that links each change to the relevant 13F source filing and explains the timing limitations to its reader.

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API endpoints

EndpointDescription
POST /v1/owners/13f/compareCompare the latest two parsable reports for a manager CIK
GET /v1/owners/13fRetrieve a normalized 13F report, with optional quarter selection

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Why SEC API for 13F comparison

What to checkWhy it matters
Filing date versus report date13F data is delayed. The report date and the date the SEC received it answer different questions.
Added or removed versus changedThe response labels each position, but a changed row does not explain the manager’s decision.
Shares versus reported valueReported value is not a live market value and can change independently of share count.
Source filingA comparison is a navigation aid. Review the source 13F before citing a position change.

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Get started

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