What Is SEC Form 4? Definition and Example
What a Form 4 filing is, who has to file it and how fast, and how to read the transaction codes without over-reading them.
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What Is Insider Buying? Definition and Example
What counts as insider buying, how it is reported on Form 4, and what research says about when it is a useful signal.
Key takeaways
- Insider buying is when a company’s officers, directors or 10%+ owners buy its shares with their own money; it must be reported on SEC Form 4 within two business days.
- Research by Cohen, Malloy and Pomorski (2012) found that “opportunistic” insider trades predicted returns, while “routine” ones carried roughly no signal.
- Open-market buys say more than option exercises, grants or planned purchases.
- Several insiders buying at once (a cluster) is commonly read as a stronger signal than one buyer, but it is still not a guarantee.
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What is insider buying?
An insider is an officer, a director or an owner of more than 10% of a company’s shares. When one of them buys stock in the open market, it is insider buying. The SEC’s Forms 3, 4 and 5 bulletin states that Form 4 must be filed within two business days of the trade, so these buys become public quickly, unlike a 13F.
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Which insider trades matter?
| Transaction | What it usually signals |
|---|---|
| Open-market purchase | The most informative: the insider chose to put cash in |
| Several insiders buying in the same weeks | Read by many investors as a stronger signal |
| Option exercise or stock grant | Little: part of pay, not a market view |
| Routine purchase on a schedule | Little: happens every year regardless of outlook |
Is insider buying a good signal?
Sometimes. In “Decoding Inside Information” (Journal of Finance, 2012), Cohen, Malloy and Pomorski split insiders into routine traders, who trade in the same pattern each year, and opportunistic ones. A value-weighted portfolio of opportunistic trades earned about 82 basis points a month in abnormal returns in their sample; routine trades earned roughly zero. That is a historical, academic result before costs, not a trading rule.
Illustrative: a CFO who has never bought before spends $400,000 on shares after a 30% fall. That is a different message from a director whose purchase every March is a habit.
How investors use it
Insider activity works best as one input next to fundamentals and analyst views. Selling is a weaker signal, because insiders sell for taxes, diversification and purchases (see insider selling). More in how to track smart money.
Common mistakes
- Counting grants and option exercises as buys.
- Ignoring size: a purchase that is small next to the insider’s pay says little.
- Treating one buy as a reason on its own to own the stock.
See insider buying with Exent
- Open a stock in Stocks Radar to see insider, congress and 13F “smart money” activity.
- Portfolio Analysis shows analyst and insider activity on the holdings you upload.
Frequently asked questions
Within two business days of the trade, on SEC Form 4, according to the SEC. The filings are public on EDGAR.
Not necessarily. Insiders sell for many personal reasons, so selling is usually read as a weaker signal than buying.
A cluster buy is when several insiders of the same company buy shares within a short period. Many investors treat it as stronger than a single purchase.
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Educational content, not investment advice. Examples are illustrative; past performance does not guarantee future results.