13F Filing Deadlines and Why Holdings Data Is Always a Bit Stale

Form 13F always arrives late, by design. The rule gives institutional managers a six and a half week window to report, and some of them ask the SEC to keep individual positions out of public view even longer. If you are using 13F data to study institutional ownership, the deadline mechanics explain most of what looks confusing about the data: why two managers filing the "same quarter" can post on different days, why a position can appear months after a manager bought it, and why an older filing sometimes gets revised.

The 45-day deadline

Rule 13f-1 under Section 13(f) of the Securities Exchange Act of 1934 requires every institutional investment manager with investment discretion over at least $100 million in Section 13(f) securities to file Form 13F within 45 days after the last day of each calendar quarter. That gives four filing windows a year:

There is no extension mechanism built into the form itself. A manager either files on time or becomes delinquent, and the SEC's EDGAR full text search and enforcement pages both make delinquent 13F filers visible to the public.

Why most filings cluster near the deadline

Nothing in the rule requires early filing, and most large managers file in the final days of the 45-day window rather than the first. That is partly operational: compiling a complete, accurate information table across every account a manager has discretion over takes time, and filing earlier gives competitors more time to see positions before the manager is ready to disclose changes. The practical effect for anyone reading the data is that holdings are usually reported as close to six weeks stale as the rule allows, not fresher.

What this means for comparisons

Because filings bunch up near the deadline, most of the public 13F data for a given quarter becomes available over just a few days. If you are comparing a manager's positions quarter over quarter, use the period field in the data rather than the filing date, since the filing date tells you when the report was submitted, not what the holdings represent.

Confidential treatment extends the delay further

Section 13(f)(4) lets the SEC prevent or delay public disclosure of specific holdings when disclosure would reveal an ongoing trading strategy. A manager uses this by filing a confidential Form 13F along with a request letter, both submitted electronically through EDGAR since 2023.

A confidential treatment request can run for three months, six months, nine months or a year, measured from the original quarterly filing deadline. If the manager wants to keep the same positions confidential past that period, it has to file a new request before the current one expires.

When confidential treatment expires without a renewal, or when the SEC denies the request, the manager has to disclose the withheld holdings. According to the SEC's Form 13F FAQ, the manager must file an amendment within six business days of the expiration or the denial notice, adding the previously withheld positions to its public report.

The 13F NOTICE and COMBINATION REPORT checkboxes

Not every manager that has to file ends up listing its own holdings. The cover page of Form 13F has two checkboxes that describe this:

A notice or combination filer also lists the other managers reporting on its behalf, identified by their 13F file number. If you are trying to reconstruct a parent company's full position in a security, you may need to pull filings from several related CIKs rather than one.

Amendments and why older filings can change

A 13F-HR/A amendment can appear long after the original filing for several reasons:

1. Confidential treatment expired or was denied, and the manager added the withheld positions, as described above.
2. The manager found an error in the original information table, such as a wrong CUSIP or share count, and refiled to correct it.
3. A late position was added that should have been in the original report.

Because amendments carry the same period of report as the original filing but a later filed date, any analysis that groups by filing date instead of reporting period can double count a manager for one quarter.

Working with 13F deadlines and amendments in code

SecFeed exposes both the original and amended reports with the period and filer fields intact, so you can see every version filed for a given quarter. To pull every 13F-HR and 13F-HR/A filed by one manager:

curl "https://secfeedapi.com/v1/form-13f?cik=1067983" \
  -H "Authorization: Bearer YOUR_API_KEY"

Each result includes the report type, the period, and the filed date, so you can tell an original report from a later amendment:

{
  "cik": "1067983",
  "formType": "13F-HR/A",
  "period": "06-30-2026",
  "filedAt": "2026-09-02",
  "manager": "EXAMPLE CAPITAL MANAGEMENT LLC"
}

In Python, filtering for amendments specifically looks like this:

from secfeed import Client

sf = Client("YOUR_API_KEY")
filings = sf.filings('cik:1067983 AND formType:"13F-HR/A"')
for f in filings:
    print(f["period"], f["filedAt"])

To see the position-level rows for a given period, including any that were added by amendment, query the holdings endpoint by CIK and period as described in our guide to 13F filings.

Frequently asked questions

What happens if a manager misses the 13F deadline?

The manager becomes delinquent. There is no grace period or automatic extension in Rule 13f-1. Delinquent filers are visible through EDGAR, and the SEC has brought enforcement actions against managers who repeatedly file late or not at all.

Can I find out which holdings were kept confidential?

Not while they are under confidential treatment, since that is the point of the request. Once the treatment period expires or is denied, the amendment that adds those holdings becomes public, and you can identify it by its later filed date and the 13F-HR/A form type for that period.

Does a 13F NOTICE filer have any holdings of its own?

No. A manager that checks the 13F NOTICE box is stating that all of its qualifying holdings are reported by other managers listed on its cover page. You will not find position rows under that manager's own report for that period.

How long can confidential treatment delay a holding?

Up to one year from the original quarterly filing deadline per request, and a manager can file a new request before the current one expires to keep specific holdings confidential longer, subject to SEC approval.