Insider Holdings Dedup

The default join of "all insider filings → sum of shares" overcounts positions, often by 2–10x. The reason: SEC rules require multiple related parties (funds, GPs, advisers, family members, trustees, beneficial owners) to each file a 13D/G or Form 4 covering the SAME underlying shares. Naive summation = fictional ownership numbers.

Core principle

Beneficial ownership is per-share, not per-filer. If three filers report the same 1,000,000 shares because of a shared-voting-power arrangement, the position is 1,000,000 — not 3,000,000.

The reverse is also true: separate parties may individually file 13D/G for distinct positions. You cannot blindly dedup either; you must read the filings.

Where double-counting happens

Schedule 13D / 13G groups

A typical activist or institutional 13D group:

Filer 1: The fund (Limited Partnership)        — reports 1,000,000 sh
Filer 2: The fund's GP (LLC)                   — reports 1,000,000 sh
Filer 3: The investment manager / adviser      — reports 1,000,000 sh
Filer 4: The CEO / managing member (individual) — reports 1,000,000 sh

All four are filing the same SC 13D as a "group". The cover page of each filing reports the same 1,000,000 shares. Naive sum = 4,000,000; true position = 1,000,000.

Form 4 transaction filings

When an executive transacts through a trust, an LLC, or a family office, multiple Form 4s may be filed for the same transaction:

• One by the executive
• One by the trust / LLC entity
• One by the family member (spouse / dependent) if reporting required

The transaction S 50,000 @ $10.00 may appear three times for what is one sale.

13G institutional cluster

Vanguard, BlackRock, and similar issuers file at the asset-manager level with multiple subsidiary entities. Same beneficial position, multiple cover-page disclosures.

Dedup rules (in priority order)

1. Group identity (Item 2). If multiple 13D/G filings list each

other as members of the same Section 13(d) group, treat as ONE position. The cover-page share counts of all members are typically identical (or report sub-allocations summing to the group total).

1. Shared voting / dispositive power. Schedule 13D Item 5 reports

"sole" vs "shared" voting and dispositive power. When two filers each report shared power over the same N shares, those N shares appear once, not twice.

1. Family attribution. Spouse and dependent-children holdings

are reported on the executive's Form 4 with footnotes ("shares held by spouse"). If the spouse files separately, dedup against the executive's filing.

1. Entity layering. Fund → GP → Adviser → Managing Member is one

chain. If the chain reports the SAME shares at each level, dedup to the lowest economic owner (typically the fund / LP).

1. Joint reporters on a single 13D/G. The cover page lists all

joint filers; the agreement under Item 6 typically attaches the joint filing agreement. Treat as one filing for sum purposes.

What is NOT a duplicate

These look similar but represent distinct positions:

• Different share classes. Class A and Class B common are distinct

even when held by the same entity.

• Different Section 13(d) groups. Two unrelated activist funds

each filing 13Ds at the same time on the same issuer are independent positions.

• Direct vs derivative holdings. A Form 4 reporting common stock

+ an option = two distinct economic exposures, not a duplicate.

• Old amendments superseded by new ones. When SC 13D/A (amendment

3) supersedes SC 13D/A (amendment 2), only the latest counts toward current holdings — but for an event-time series, both matter.

Workflow when computing total insider holdings

1. Pull all 13D, 13G, 13D/A, 13G/A filings for the issuer in the

target window.

1. Group filings by reported group identity (Item 2):

• All filings citing each other on the cover page = one group.
• Each group has ONE position (use the cover-page share count of

any member; they should match).

1. For each independent group, compute the LATEST reported holding

per amendment chain.

1. Compute sum across DISTINCT groups only.
2. Cross-check against atm-detection and recent 424B activity:

total beneficial holdings + ATM-issued shares + outstanding shares should reconcile to total shares outstanding within ~5%. Larger gaps = missed dilution event or missed group.

Workflow when computing insider transaction volume (Form 4)

1. Pull all Form 4s for the issuer in the target window.
2. Group by transaction date + transaction code + share count +

per-share price. Identical-tuple Form 4s filed by related parties are likely the same transaction reported through multiple filers (e.g., trust + executive + spouse).

1. Apply attribution: footnotes commonly say "shares held by [X]

for the benefit of [Y]". The economic owner is one party.

1. Sum DEDUPED transactions only.

Special cases

• Form 144 (notice of intent to sell). Not an executed transaction;

do not include in completed-sale tallies. The actual sale (if it occurs) shows up later as a Form 4. Treating 144s as Form 4s is one of the most common quant bugs. (See sec-filing-types.)

• 13F filings. Are NOT 13D/G — they cover institutional MANAGER

holdings with a 45-day lag, no 5% ownership threshold, and no filer-group dedup logic applies. Don't mix 13F and 13D/G summation.

• CUSIP changes (reverse splits / mergers). If the issuer's CUSIP

changed mid-window, ownership filings on the old CUSIP and new CUSIP are the same position; reconcile by ticker history, not by CUSIP.

Phrases that should trigger this skill

• "total insider holdings"
• "insider ownership %"
• "13D vs 13G dedup"
• "joint filers"
• "are these Form 4s duplicates"
• "13D group"
• "beneficial ownership reconciliation"

What this skill is NOT

This is not a beneficial-ownership extractor. It defines the deduplication semantics so a downstream summation produces a real number rather than a multi-counted fiction. Combine with sec-filing-types for form context and lookahead-safety for historical reconstruction of holdings.