> ## Documentation Index
> Fetch the complete documentation index at: https://docs.secapi.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Build a 13F Holdings Tracker Agent

> Create a Python job that records the latest 13F comparison for a manager CIK.

Retrieve the latest two parsable Form 13F reports for one manager and save the
returned comparison. This job creates an evidence artifact; it does not infer
trades, performance, or current ownership.

## Prerequisites

* Python 3.9+, `requests`, and `SECAPI_API_KEY`.
* A manager CIK and durable storage for production results.

```bash theme={null}
python -m pip install requests
export SECAPI_API_KEY="your_api_key"
```

Create `track_13f.py`:

```python theme={null}
import json, os
from datetime import datetime, timezone
from pathlib import Path
import requests

cik = "0001067983"
response = requests.post(
    "https://api.secapi.ai/v1/owners/13f/compare",
    headers={"x-api-key": os.environ["SECAPI_API_KEY"]},
    json={"cik": cik, "limit": 50}, timeout=30,
)
response.raise_for_status()
payload = response.json()
stamp = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
output = Path(f"13f-compare-{cik}-{stamp}.json")
output.write_text(json.dumps(payload, indent=2) + "\n")
print({
    "output": str(output),
    "requestId": payload.get("requestId"),
    "traceparent": payload.get("traceparent"),
})
```

Run `python track_13f.py`. A successful run writes the service-selected
comparison and prints the file path and request metadata. Keep the original
JSON, manager CIK, report dates, filing dates, source accessions or URLs, and
request metadata with every derived summary. The underlying Form 13F reports
remain the source for a material statement.

## Common errors

* `400`: provide the reporting manager's CIK, not a portfolio-company ticker.
* `401` or `403`: the key is missing, invalid, or not entitled to the route.
* An unavailable comparison can mean fewer than two parsable reports; it is not
  evidence of no exposure or no change.

## Production considerations

Use an idempotent object key that includes the manager and retrieval time, keep
bounded retries for temporary `5xx` responses, and do not mark a manager
unchanged after an incomplete request. A 13F is a delayed snapshot of reportable
securities, so label a row change as a comparison between selected reports.

## Limitation and next steps

13F data is delayed and limited to reportable securities. A new or closed
position is a change between selected reports, not proof of a real-time trade.

List a manager's filing history with [13F ownership](/api-reference/owners),
then schedule the job after the relevant filing window.