A form filed when an investor acquires more than 5% of a company with active intentions.
Definition
Often called a 'beneficial ownership report,' Schedule 13D must be filed with the SEC within 10 days after an entity acquires more than 5% of any class of a company's shares, provided they intend to actively influence the management or control of the company.
Why it matters for Whale Tracking
13D filings are the bat-signal of activist investing. They alert the market that a 'whale' has arrived and intends to force changes—like firing the CEO, selling divisions, or pushing for a buyout—which almost always causes high stock volatility.
Real-World Example
"If Carl Icahn quietly buys 6% of a struggling tech firm, he must drop a Schedule 13D. Algorithmic news feeds instantly blast this out, and the stock price typically surges as retail and institutional money follow his lead."