Schedule 13D vs 13G: How to Tell Activist and Passive Owners Apart

Any time someone crosses 5% ownership of a public company's voting class, the SEC wants to know. What they file next, Schedule 13D or Schedule 13G, tells you whether that 5% owner is an activist with plans for the company or an institution quietly holding a large position. Reading the right schedule, and knowing its deadlines, is the fastest way to understand what a large new owner is actually doing.

What triggers either filing

Section 13(d) of the Securities Exchange Act of 1934 requires any person or group that acquires beneficial ownership of more than 5% of a registered voting class to report it. The 5% threshold and the definition of beneficial ownership are the same for both schedules. What differs is the filer's purpose and the deadlines that follow.

Schedule 13D: ownership with a purpose

Schedule 13D is the default filing for anyone crossing 5% who does not qualify for the shorter 13G alternative. It is built for holders who may try to influence or change control of the company, and it requires more disclosure than 13G:

• Background and identity of the reporting person
• Source and amount of funds used for the purchase
• Purpose of the transaction, including any plans to change the board, capital structure, or business of the issuer
• Number of shares owned and the percentage of class
• Any contracts, arrangements or understandings with other parties regarding the issuer's securities

The purpose section is why 13D filings move markets. A 13D that discloses an intent to seek board seats or push for a sale reads very differently from a 13G that simply reports a large passive position.

Deadlines for Schedule 13D

Under amendments the SEC adopted in 2023, effective for compliance from September 30, 2024, an initial Schedule 13D is due within 5 business days of crossing the 5% threshold, down from the previous 10 calendar days. Material changes to a previously filed 13D, such as a change in purpose or a meaningful change in ownership, must be reported in an amendment within 2 business days.

Schedule 13G: three kinds of filers without a control purpose

Schedule 13G is shorter and is available only to filers who are not seeking to influence or control the issuer. Rule 13d-1 splits eligible 13G filers into three categories:

A QII or passive filer loses eligibility for 13G, and must switch to 13D, if its purpose changes to influence or control the company, or if a passive investor's stake reaches 20% or more.

Deadlines for Schedule 13G

Deadlines differ by category under the same 2023 amendments:

The quarterly cadence for most 13G filers is why institutional 13G ownership data updates less often than 13D data. A 13D can post within days of a transaction, while a QII's 13G might not reflect a position change until the following quarter's amendment.

Reading percentages correctly

Both schedules report the percent of class, calculated against shares outstanding as disclosed by the issuer, not against the filer's own count of total shares in circulation. When comparing filings across managers, check the maxPercentOfClass style figures rather than assuming a consistent share count, since issuers update shares outstanding between filings.

Groups and aggregation

When two or more people act as a group for the purpose of acquiring, holding, voting or disposing of shares, Section 13(d)(3) treats the group as a single "person" for the 5% threshold. A group that collectively crosses 5% must file, even if no individual member holds that much. This is one of the most common reasons an activist campaign shows several related filers on the same Schedule 13D.

Working with 13D and 13G data in code

SecFeed parses both schedules into the same structured fields, so you can filter across activist and passive positions in one query. For example, to find recent 13D filings reporting at least 10% ownership:

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

Each row includes the issuer, the reporting person, and their voting and dispositive power:

{
  "issuer": "EXAMPLE CORP",
  "cusip": "123456789",
  "formType": "SCHEDULE 13D",
  "filedAt": "2026-09-18",
  "reportingPerson": "EXAMPLE CAPITAL MANAGEMENT LLC",
  "soleVotingPower": 4200000,
  "maxPercentOfClass": 11.4
}

To track whether a filer has switched from 13G to 13D for the same issuer, which can signal a change in intent, query by CIK and compare form types over time:

from secfeed import Client

sf = Client("YOUR_API_KEY")
filings = sf.filings('cik:1067983 AND formType:("SCHEDULE 13D" OR "SCHEDULE 13G")')
for f in sorted(filings, key=lambda x: x["filedAt"]):
    print(f["filedAt"], f["formType"])

For a deeper look at how institutional ownership compares to quarterly 13F holdings, see our guide to 13F filings.

Frequently asked questions

What is the main difference between Schedule 13D and 13G?

Schedule 13D is for filers who may seek to influence or control the issuer and requires disclosing their purpose and plans. Schedule 13G is a shorter form limited to qualified institutions, passive investors below 20% and exempt holders who certify they have no control purpose.

How fast does a 13D have to be filed after crossing 5%?

Within 5 business days of crossing the 5% threshold, under the deadlines that took effect for compliance starting September 30, 2024.

Can a filer switch from Schedule 13G to Schedule 13D?

Yes. If a 13G filer's intent changes to influence or control the issuer, or a passive investor's stake reaches 20% or more, it must switch to filing Schedule 13D and loses eligibility to file on 13G going forward.

Why do some 13G filings only update once a quarter?

Qualified institutional investors and exempt investors file and amend Schedule 13G on a quarterly cycle: 45 days after the quarter in which eligibility arose or a material change occurred. Passive investors file their initial 13G faster, within 5 business days, but also amend on the 45-day quarterly cycle.