Is There an SEC Definition of "Significant Shareholder"?

Search "significant shareholder definition SEC" and you will not find a rule by that name, because there is not one. The SEC's own regulations never use the phrase "significant shareholder" as a defined term. What you are actually looking for is one of several different ownership thresholds, each written into a different rule for a different purpose, and each with its own percentage.

This guide covers where those thresholds actually come from, what each one requires, and how to pull a company's 5% owners directly from SEC data.

There is no SEC rule called "significant shareholder"

"Significant shareholder," "substantial shareholder" and "major shareholder" are common phrases in financial writing, company bylaws and private contracts, but none of them are terms defined in the Securities Exchange Act of 1934 or the SEC's rules under it. Some other countries' securities laws do define a version of the term directly (Canadian securities law, for instance, defines "significant shareholder" by reference to beneficial ownership or control of a company's securities), which is part of why the phrase feels like it should have one clean US answer. It does not.

What the SEC actually regulates is beneficial ownership at specific percentage thresholds, and which threshold applies depends on which rule you are asking about.

Where the 5% line comes from: Section 13(d) and Item 403

The most common threshold people mean by "significant shareholder" is 5%. Two separate SEC requirements use it:

• Section 13(d) of the Exchange Act requires any person or group that acquires beneficial ownership of more than 5% of a registered class of voting equity securities to file a Schedule 13D, or a shorter Schedule 13G for qualified passive and institutional holders. "Beneficial ownership" for this purpose is defined in Rule 13d-3: it reaches shared voting or investment power, not just shares held directly in one's own name.
• Item 403 of Regulation S-K requires a company's proxy statement and annual report to list every person known to the company to beneficially own more than 5% of any class of its voting securities, using that same Rule 13d-3 definition of beneficial ownership. This is the "5% owner" table that shows up near the top of most proxy statements.

Where the 10% line comes from: Section 16 insiders

A different threshold, 10%, comes from Section 16 of the Exchange Act. Anyone who beneficially owns more than 10% of a registered class of equity securities is a Section 16 insider alongside the company's officers and directors. That status brings three separate obligations: filing a Form 3 when the position is first taken, a Form 4 within two business days of most later transactions, and giving up any "short-swing" profit from buying and selling the same security within six months, which the issuer can recover regardless of intent.

SEC Form 4 explained covers how to read those insider transaction filings once a holder crosses the 10% line.

Exchange listing rules use their own thresholds

Beyond federal securities law, the stock exchanges set their own ownership thresholds for their own purposes, and these are where phrases like "substantial shareholder" show up most often in practice. The NYSE's listing rule on related-party transactions (Section 312.03) requires shareholder approval for certain issuances to a "Related Party" holding a 5% or greater interest, and a separate NYSE provision treats a holder of less than 5% of outstanding shares or voting power as not a "substantial security holder" for that purpose. Nasdaq's related listing rules use their own 20% thresholds for shareholder approval of stock issuances, with no equivalent to the NYSE's related-party carve-out. None of this is SEC rule text: it is exchange rule text that the SEC reviews and approves, which is a different thing.

Thresholds compared

How to find a company's largest shareholders

The practical question behind the search is usually simpler than the terminology: who owns a meaningful stake in this company? Three sources answer it, each with a different lag:

1. The proxy statement's Item 403 table is the most complete snapshot, but it is only published once a year (or before a special meeting) and can be months old by the time you read it.
2. Schedule 13D and 13G filings update continuously as holders cross the 5% line or change their position, so they are closer to current than the annual proxy table.
3. Form 13F shows institutional managers' reported positions, but only those managers over the $100 million discretion threshold, and only long positions in Section 13(f) securities, so it will miss smaller or non-institutional 5% holders entirely.

Pulling 5% owner data in code

SecFeed parses every Schedule 13D and 13G filing into flat fields, including the percent of class each reporting person holds, so you can filter directly for stakes above a threshold instead of opening each filing.

curl "https://secfeedapi.com/v1/form-13d-13g?formType=SCHEDULE 13D&flat.maxPercentOfClass__gte=10&fields=flat" \
  -H "Authorization: Bearer YOUR_API_KEY"

A matching row carries the issuer, the reporting person and the percent of class reported on the cover page:

{
  "issuerName": "EXAMPLE CAPITAL CORP",
  "cik": "0001234567",
  "reportingPersonName": "EXAMPLE ACTIVIST PARTNERS LP",
  "maxPercentOfClass": 12.4,
  "soleVotingPower": 4100000,
  "sharedVotingPower": 0,
  "filedAt": "2026-10-02"
}

In Python, the same filter works through the client:

from secfeed import Client

sf = Client("YOUR_API_KEY")
rows = sf.form_13d_13g(form_type="SCHEDULE 13D", flat__maxPercentOfClass__gte=10)
for r in rows:
    print(r["issuerName"], r["reportingPersonName"], r["maxPercentOfClass"])

The Schedule 13D/13G API documents every cover-page field, including voting and dispositive power broken out separately from the percent of class.

What a "significant shareholder" is not

A few related terms get mixed in with searches for this phrase, and it is worth separating them:

• Controlling shareholder usually means someone who owns more than half of a company's voting power, or who otherwise controls the outcome of shareholder votes in practice; it is a different, higher bar than any 5% or 10% reporting threshold.
• Affiliate, under Rule 405 of the Securities Act, means a person who controls, is controlled by, or is under common control with a company. Ownership above 10% is often evidence of affiliate status, but the test is control, not a fixed percentage.
• Insider is broader than any single ownership percentage: officers and directors are insiders regardless of how many shares they hold.

Frequently asked questions

What percentage makes someone a significant shareholder?

There is no single SEC-defined percentage. Depending on which rule applies, the relevant line is 5% (Schedule 13D/13G and proxy disclosure under Item 403), 10% (Section 16 insider status), or a threshold an individual stock exchange or company sets for its own purposes.

Is a 5% owner automatically an insider?

Not necessarily. A 5% owner must be reported in the company's proxy statement and may need to file a Schedule 13D or 13G, but Section 16 insider status, with its Form 3/4/5 filing duties, only attaches above 10% (or to officers and directors regardless of ownership).

Where can I see a company's significant shareholders?

The clearest public source is the 5% beneficial ownership table in the company's most recent proxy statement (Item 403 of Regulation S-K), supplemented by any Schedule 13D or 13G filed since that proxy, since those update faster than the annual proxy table.

Does Form 13F show significant shareholders?

Only partly. Form 13F reports institutional managers' long positions over a $100 million discretion threshold, but it does not identify 5% ownership directly, and it misses individual holders, smaller institutions and non-equity positions entirely.

Why do other countries define "significant shareholder" but the US does not?

Securities regulators differ in drafting style. Some jurisdictions, including Canada, write a single defined term covering beneficial ownership or control at a stated threshold. US federal securities law instead layers several separate rules, each written for a specific purpose (reporting, insider trading, proxy disclosure), so no single definition covers all of them.