Own more than 5% of a public company’s voting shares and you have to tell the market. The filing you use, a Schedule 13D or a 13G, usually says whether you’re along for the ride or might grab the wheel.
Two forms, two intentions
A 13D is the long form. The holder has to say why they bought and what they might do, such as pushing for board seats, a sale of the company or a new strategy. A 13G is the short form for holders with no plans to steer the company, like index funds.
Who
Holders who may push for change, and anyone who can’t use the short form
When
Within 5 business days of crossing 5%
Tells you
Their purpose and any plans for the company
Who
Passive holders, like index funds and other big institutions
When
Institutions: 45 days after the quarter they cross 5%. Other passive holders: 5 business days
Tells you
The stake, plus a statement that they don’t aim to control the company
A 13G says “I own this.” A 13D says “I own this, and I may have ideas.”
Why activists matter
A new 13D from a known activist may include a letter to the board as an exhibit. The purpose section (Item 4) is where the story is, so read it, not just the percentage.
Watch for the switch
A holder who files a 13G and later switches to a 13D no longer counts as passive: they may now want to influence the company, or their stake has grown past what the short form allows. Either way it’s one of the more telling events in ownership data, and it’s easy to miss if you only look at the numbers.