How to Read a 13F Amendment Without Confusing It for a New Filing

What Is a 13F Amendment?

A 13F amendment (13F-HR/A) is a corrected version of a previously filed 13F report. It replaces the original filing for that quarter — it does not represent new trading activity or new positions. When you see an amendment, the filer is saying: "Our original Q4 2025 filing had errors. Here is the corrected version."

Why Do Amendments Happen?

Common reasons:

• Incorrect share counts: A position was reported with the wrong number of shares
• Missing positions: A holding was accidentally omitted from the original filing
• Wrong CUSIP: A security was reported under the wrong identifier
• Voting authority corrections: The sole/shared/none breakdown was wrong
• Confidential treatment: A previously confidential position is now disclosed via amendment

How 13F Insight Handles Amendments

On 13F Insight, amendments automatically supersede the original filing for the same quarter. When you view a filer's holdings page, you always see the most recent version — whether that's the original or an amendment. You don't need to manually check for amendments.

Key behavior:

• Original + Amendment for same quarter: Amendment data replaces the original entirely
• Multiple amendments: The latest amendment takes priority
• AUM history: Reflects the most current data for each quarter

How to Spot an Amendment

In SEC EDGAR, amendments are identified by:

• Form type: "13F-HR/A" (the "/A" suffix means amendment)
• Filing date: Later than the original for the same report period
• Report date: Same quarter-end as the original (e.g., both say December 31, 2025)

If you see two filings for the same filer with the same report date, the later one is the amendment — and the one you should use.

Common Mistakes When Reading Amendments

Mistake #1: Treating an amendment as a new quarter's data

An amendment filed in March 2026 for the December 31, 2025 report date is not March 2026 data. It's a correction of Q4 2025 data. The positions reflect what the filer held on December 31, 2025.

Mistake #2: Calculating QoQ changes from original to amendment

If a filer's original Q4 filing showed 1M shares of AAPL and the amendment shows 1.2M shares, that doesn't mean they bought 200K shares. It means the original filing was wrong — they held 1.2M shares all along.

Mistake #3: Assuming amendments signal problems

Amendments are routine. Large filers with thousands of positions regularly file corrections for minor data issues. An amendment is a sign of data quality improvement, not a red flag.

Special Case: Confidential Treatment Amendments

Some filers initially file 13Fs with certain positions withheld under a "confidential treatment" request to the SEC. When the confidential period expires, the filer submits an amendment disclosing those positions. These can be interesting because they reveal positions the filer wanted to accumulate without market knowledge — often activist or large strategic stakes.

FAQ

Do I need to check for amendments manually?

Not on 13F Insight. The platform automatically uses the most recent version of each quarterly filing. When you view holdings data, you're always seeing the corrected version if an amendment exists.

How common are amendments?

Very common for large filers. A fund reporting 10,000+ positions will frequently file amendments to correct minor errors. Smaller filers with concentrated portfolios file amendments less often.

Can an amendment change a filer's AUM significantly?

Rarely. Most amendments correct a few positions without materially changing total AUM. However, confidential treatment amendments can add significant previously undisclosed positions.

Where can I see the original vs amended filing?

On SEC EDGAR, search for the filer's CIK and look at all 13F-HR and 13F-HR/A filings. On 13F Insight, the holdings page always shows the final corrected version.