What are Schedule 13D and 13G?
Under Section 13(d) of the Securities Exchange Act, anyone who acquires beneficial ownership of more than 5% of a class of a public company's voting shares must disclose it. That includes individuals, hedge funds, private equity firms, corporations and groups acting together. They do it on one of two forms: Schedule 13D or the shorter Schedule 13G.
The key difference: intent
The choice of form depends on what the investor intends to do. If they may seek to influence or control the company, through board seats, a sale, a new strategy or a change in capital return, they must file a 13D. If they are holding passively, they can file a 13G.
Schedule 13G · passive
No plan to influence control
- Passive investors: within 5 business days
- Institutions and exempt holders: 45 days after the quarter they cross 5%
- Short form, little detail on intent
Schedule 13D · active
May seek board seats, a sale or a new strategy
- Within 5 business days of crossing 5%
- Item 4 must say what the investor intends to do
- Amend within 2 business days of a material change
A 13G holder who decides to push for change must switch to a 13D within 5 business days, and cannot vote or buy more shares until 10 days after filing it.
Deadlines after the 2024 rules
The SEC shortened these deadlines in October 2023, the first change since 1968 for 13D and 1977 for 13G. Compliance with the new 13G deadlines began on September 30, 2024, and both schedules are now filed in a structured, machine-readable format.
| Filer | Initial filing | Amendments |
|---|---|---|
| 13D (may seek control) | 5 business days after crossing 5% | 2 business days after a material change |
| 13G, qualified institutions and exempt investors | 45 days after the quarter in which they cross 5% | 45 days after the quarter of a material change; sooner above 10% |
| 13G, other passive investors | 5 business days after crossing 5% | 45 days after the quarter; sooner above 10% |
Item 4: what the investor wants
Item 4 of a Schedule 13D, Purpose of Transaction, is where the investor must describe any plans to change the company: acquisitions, a sale, board changes, capital structure, dividends or strategy. It is the most important part of the filing and also the most padded, because lawyers routinely list every possible action to preserve flexibility.
SignalX uses AI to read Item 4 and ignore the standard reservation-of-rights language, then classifies what the investor actually says it will do and writes a one-line summary.
What activists actually ask for
Across the 218 Schedule 13D campaigns SignalX classified for the year to October 2026, the stated intentions broke down like this.
Schedule 13D by stated intent · year to Oct 2026 · 218 filings
- Inv.Investment onlyInvestment only45.0% · 98
- BoardBoard seatsBoard seats15.6% · 34
- CtrlControl or takeoverControl or takeover12.8% · 28
- Fin.Financing stakeFinancing stake11.5% · 25
- SaleSale or mergerSale or merger7.3% · 16
- OpsStrategy and operationsStrategy and operations5.5% · 12
The largest group is "investment only": many 13D filers are strategic investors, founders or lenders who file a 13D because they cannot certify passivity, not because they plan a campaign. The filings that point to an active campaign are the ones asking for board seats, a sale or a change in strategy. In 86 of the 218 cases, the target company's own officers or directors also bought shares within 90 days before or after the filing.
When a 13G becomes a 13D
A passive holder who decides to push for change must switch from a 13G to a 13D, and cannot vote the shares or buy more until 10 days after filing the 13D. That conversion is one of the clearest signals in ownership data: an investor who already knows the company well has decided to get involved. SignalX found 26 conversions in the year to October 2026.
How to read a 13D
- Cover page: who filed, the percentage owned and the date of the event that triggered the filing.
- Item 3: how the stake was paid for, which can reveal leverage.
- Item 4: the plans. Read past the boilerplate for anything specific.
- Item 5: recent transactions, which show how fast the stake was built.
- Item 6 and exhibits: derivatives, agreements with other investors and letters to the board.
For the quarterly view of what large funds own, see how 13F filings work.