Schedule 13D Explained: Who Files It and the New Deadlines

A Schedule 13D is the filing a 5% owner makes with the SEC when they are not just investing passively but may try to change how the company is run. It names the holder, where the money came from, and what they plan to do next, and under rules that took effect in 2024 it has to show up faster than it used to.

This guide covers who has to file, what the schedule contains, the deadlines as they stand today, and how to pull every Schedule 13D for a company or a filer as structured data instead of reading the filing by hand.

Who has to file a Schedule 13D?

Section 13(d) of the Securities Exchange Act of 1934 requires a filing from any person or group that acquires beneficial ownership of more than 5% of a class of voting equity securities registered under the Act, if that person has not disqualified themselves from the passive Schedule 13G alternative.

Beneficial ownership here is defined by Rule 13d-3: it looks at who holds voting power or investment power over the shares, directly or through an agreement, and it is not limited to the name on the stock record. Shares you have the right to acquire within 60 days, for example through an option, generally count too. SecFeed's guide to beneficial ownership covers how this test differs from the one used for Section 16 insiders.

Three groups of holders can file the shorter Schedule 13G instead of 13D:

• Qualified institutional investors (Rule 13d-1(b)): banks, broker-dealers, insurance companies, registered investment advisers and a few other regulated entities, as long as the securities were acquired in the ordinary course of business and not to influence control.
• Passive investors (Rule 13d-1(c)): anyone who holds less than 20% and has no intent to change or influence control of the issuer.
• Exempt investors (Rule 13d-1(d)): holders who crossed 5% before the issuer registered the class, or in a few other narrow situations.

Anyone who does not fit one of those categories, or who loses eligibility (for example, a passive holder who starts pushing for board seats), must file Schedule 13D. Schedule 13D vs 13G walks through that distinction in more detail.

What is in a Schedule 13D?

The schedule has a cover page per reporting person plus seven numbered items:

When is a Schedule 13D due?

The SEC's 2023 amendments to Regulation 13D-G (Release No. 33-11253) changed both deadlines that apply to Schedule 13D, with compliance required starting February 5, 2024:

A change is treated as material for amendment purposes once it moves the reporting person's percentage ownership by 1% or more of the class, under the bright-line test the SEC adopted alongside the new deadline. A change to the plans disclosed in Item 4 or to an arrangement disclosed in Item 6, such as entering a voting agreement, can also be material even without a share count change.

The same 2023 release also moved Schedule 13D and 13G filings to a required structured XML format, called the Schedule 13D & 13G XML technical specification, effective December 18, 2024. Before that date filers could submit the schedule as plain text or HTML; after it, every item (other than exhibits) has to be tagged data, which is what makes the cover page fields machine readable at scale.

How to read a Schedule 13D filing

A single 13D tells you a position and an intent at one point in time. To understand what is happening with a stock, you usually need to look at the sequence:

1. The original Schedule 13D establishes the position and states the purpose in Item 4.
2. Amendments (Schedule 13D/A) update share counts, disclose new agreements, or change the stated purpose, for example from "general investment" to "intend to seek board representation."
3. A later Schedule 13G, if the holder drops below 5% or becomes eligible for passive treatment, or a 13D exit if they sell out entirely.

Reading only the first filing in a sequence will miss an escalation from passive to activist, which usually shows up first as a 13D/A with a changed Item 4.

Working with Schedule 13D data in code

SecFeed parses every Schedule 13D and 13G filing into structured rows, including the voting and dispositive power fields and the percent of class, so you can query 5% ownership positions without opening the XML yourself. For example, to find Schedule 13D filings (not the passive 13G) where a filer reports at least 10% of the class:

curl "https://secfeedapi.com/v1/form-13d-13g?formType=SCHEDULE%2013D&flat.maxPercentOfClass__gte=10&size=10" \
  -H "Authorization: Bearer YOUR_API_KEY"

Each row includes the issuer, the reporting person, and the ownership figures from Item 5:

{
  "formType": "SCHEDULE 13D",
  "issuerCik": "0000320193",
  "issuerName": "EXAMPLE ISSUER INC",
  "filerName": "EXAMPLE CAPITAL PARTNERS LP",
  "maxPercentOfClass": 12.4,
  "sharesSoleVotingPower": 8450000,
  "sharesSharedVotingPower": 0,
  "filedAt": "2026-09-02"
}

In Python, with the SecFeed SDK:

from secfeed import Client

sf = Client("YOUR_API_KEY")
rows = sf.form_13d_13g(cik="320193", form_type="SCHEDULE 13D")
for r in rows:
    print(r["filerName"], r["maxPercentOfClass"], r["filedAt"])

To follow one filer's full history of activist stakes over time, including amendments, see the activist stakes tutorial. The underlying dataset, with every field from the structured filing, is documented on the Schedule 13D and 13G dataset page and the Schedule 13D and 13G API product page.

Frequently asked questions

What is a Schedule 13D filing?

It is a disclosure required under Section 13(d) of the Securities Exchange Act of 1934 from any person or group that beneficially owns more than 5% of a company's voting class and has an intent, or is not eligible for the passive alternative, to influence or control the issuer. It names the holder, where the funds came from, and what they intend to do.

How is Schedule 13D different from Schedule 13G?

Both report crossing the 5% threshold, but Schedule 13G is for holders who qualify as passive investors, qualified institutional investors or exempt investors under Rule 13d-1(b), (c) or (d), and it carries lighter disclosure and a slower deadline. Schedule 13D is for everyone else, including anyone who intends to influence management, the board or the company's structure. See Schedule 13D vs 13G for the full comparison.

How long do you have to file a Schedule 13D?

Since February 5, 2024, the initial Schedule 13D is due within 5 business days of crossing the 5% threshold with control intent, down from the previous 10 calendar days. An amendment is due within 2 business days of a material change, defined as a shift of 1% or more in the percentage owned, replacing the old "promptly" standard.

Does a Schedule 13D amendment reset the clock?

No. The 2-business-day amendment deadline runs from the date of the material change itself, not from the date of the prior filing. Each material change, whether a 1% ownership shift or a new arrangement disclosed under Item 6, starts its own 2-business-day countdown.

Is Schedule 13D data available as structured data?

Yes. Since December 18, 2024, every Schedule 13D and 13G has to be filed in a structured XML format under the SEC's technical specification, which means the cover page fields, including ownership percentages and voting power, are tagged rather than free text. SecFeed parses those fields into JSON rows through the Schedule 13D and 13G API.