SEC Form 4 is the filing corporate insiders use to disclose trades in their own company's stock, and it must be submitted to the SEC within two business days of the transaction. This guide explains SEC Form 4 field by field: what each section tells you, which transaction codes matter, and the details that separate a meaningful signal from noise.

That two-day window makes Form 4 one of the most time-sensitive public datasets in financial markets. Unlike a quarterly report published months after the fact, a Form 4 is a near-real-time record of what the people closest to a company are doing with their own money. Filtered well, that record has historically produced insider signals that beat the market.

Most investors either don't know Form 4 exists or see the raw filing on EDGAR and can't parse it. If you invest from Europe, you've almost certainly never encountered it: there's no equivalent centralized system in the EU, where insider transaction data is fragmented across more than 20 national regulators, each with different formats and languages. The document itself is dense, full of SEC-specific codes, and designed for compliance officers, not retail investors.

Who files a Form 4?

Form 4 is filed by reporting persons, the individuals and entities the SEC classifies as insiders. There are three categories: officers, directors, and 10% owners.

Officers are senior executives with decision-making authority: CEOs, CFOs, COOs, CTOs, and other C-suite or VP-level leaders. These are the people who see quarterly results before anyone else.

Directors sit on the company's board. They approve strategy, review financials, and have access to material non-public information. Some directors are also large shareholders.

10% owners are entities or individuals who hold more than 10% of any class of the company's equity. These are often investment firms, family offices, or founders who've retained a large stake.

Each of these insiders has a different relationship with the company, different levels of information access, and different motivations for trading. That context matters when you're interpreting what a filing means.

The anatomy of a Form 4

A Form 4 filing has four main sections: the header, two transaction tables, and the footnotes. Here's what each one contains and why it matters.

Header: the who and the when

The top of the filing identifies the reporting person (the insider), the issuer (the company whose stock was traded), and the filing date. The filing date is not the same as the transaction date; the insider has up to two business days after the trade to file.

Pay attention to the gap between transaction date and filing date. A filing submitted on the same day as the trade suggests urgency. A filing submitted on the last possible day is normal but tells you less about conviction.

Table I: Non-derivative securities

Table I reports direct transactions in common stock, the straightforward buying and selling that most investors care about. This is where most of the action is.

Key fields:

Transaction code tells you what type of transaction occurred. The most important codes are:

• P (Purchase): An open-market buy. The insider went to the market and bought shares with their own money. This is the code that matters most for signal analysis.
• S (Sale): An open-market sale. Insiders sell for many reasons (diversification, tax planning, personal expenses), so sales are harder to interpret than purchases.
• A (Grant/Award): Stock granted by the company as compensation. Not a market transaction, since the insider didn't choose to buy.
• M (Exercise): Option exercise. The insider converted stock options into shares. Often followed by a sale (exercise-and-sell), which is typically routine compensation activity.
• F (Tax withholding): Shares surrendered to cover tax obligations on vesting equity. This is mechanical, not a conviction signal.

Most screeners and alert services treat all of these equally. They shouldn't. A CEO buying $2 million of stock on the open market (code P) is a fundamentally different event than a VP receiving a routine stock grant (code A) or selling shares to cover taxes (code F).

Shares transacted is the number of shares involved. On its own, this number is meaningless: 10,000 shares of a $5 stock is $50,000, while 10,000 shares of a $500 stock is $5 million. Always convert to dollar value.

Price per share lets you calculate the total transaction value when combined with shares. For open-market purchases, this reflects the actual price paid.

Shares owned after the transaction shows the insider's total position after the trade. This is important context: a CEO buying $500,000 of stock when they already own $50 million is different from a CEO buying $500,000 when they own $200,000. The latter is meaningfully increasing their exposure.

Table II: Derivative securities

Table II covers options, warrants, and other derivative instruments. This section is more complex and less directly useful for most investors. Option exercises (code M) show up here along with the underlying shares they convert to.

The key thing to know: derivative transactions are often part of compensation plans and pre-arranged trading schedules. They're less likely to reflect active conviction than open-market purchases in Table I.

Footnotes

The footnotes section is where the filing discloses context that doesn't fit neatly into the tables. Common disclosures include:

• 10b5-1 plan filings: The insider pre-arranged the trade through a Rule 10b5-1 plan, which means it was scheduled in advance and not based on current information. This significantly reduces the signal value.
• Gift transactions: Shares transferred as gifts, not market transactions.
• Trust holdings: Shares held indirectly through family trusts or LLCs.

Footnotes are where most investors stop reading. That's a mistake. A large purchase that turns out to be a 10b5-1 plan execution is a very different signal than a discretionary open-market buy.

A real example: what a high-conviction filing looks like

In early 2026, Palo Alto Networks CEO Nikesh Arora filed a Form 4 disclosing an open-market purchase of company stock worth roughly $10 million. Here's what each piece of that filing tells you:

• Reporting person: CEO, the highest-ranking executive at the company
• Transaction code: P, an open-market purchase rather than a grant or option exercise
• Transaction value: roughly $10 million, large by any standard and especially notable for a single filing
• Context: PANW's stock had dropped roughly 30% in the prior weeks as part of a broad SaaS selloff
• Footnotes: No 10b5-1 plan disclosed, meaning this was a discretionary buy, not a pre-scheduled transaction

Every piece of that filing points in the same direction: the CEO of a $100+ billion company chose to deploy significant personal capital into his own stock during a period of price weakness, outside of any automatic plan.

Compare that to a filing where a VP exercises 5,000 stock options (code M) and immediately sells the resulting shares (code S) to cover taxes (code F). Same form, completely different signal. The transaction codes, context, and footnotes tell you everything.

What most investors miss

The difference between a routine filing and a meaningful one usually comes down to four details that even experienced investors tend to overlook.

Not all purchases are equal. A director buying $25,000 of stock on an automatic quarterly schedule is noise. A CEO buying $10 million after a 30% price decline is a potential signal. The transaction code tells you the type of trade. The context (who bought, how much, at what price, relative to what they already own) tells you whether it means something.

Cluster buying matters. When multiple insiders at the same company buy within a short window, it can indicate shared conviction that the stock is undervalued. Research by Lakonishok and Lee (2001) and others has found that cluster purchases, where three or more insiders buy within a short period, produce meaningfully stronger subsequent returns than isolated buys.

Filing speed is information. The SEC gives insiders two business days to file. In practice, filings that arrive faster tend to be associated with more intentional trades. Late filings sometimes indicate administrative delays on routine transactions.

Transaction size relative to net worth is more telling than absolute dollars. A $100,000 purchase from a director worth $500 million is rounding error. The same purchase from a newly appointed CFO is a meaningful personal bet.

Where can you find Form 4 filings?

All Form 4 filings are publicly available on the SEC's EDGAR database at sec.gov/cgi-bin/browse-edgar. You can search by company name, ticker, or CIK number and filter for Form 4 filings.

The raw data is free and public. The SEC publishes roughly 13,000 Form 4 filings per month, about 3,000 per week. Most of them are routine: option exercises, tax withholding, small scheduled purchases. The small subset that reflects genuine executive conviction is buried in that volume. Learning to read a Form 4 is the first step. Learning to filter is what makes the data useful.

Related Reading

• The SEC Just Charged 21 People for Insider Trading. Here's Why That's Not What We Track.: The legal disclosure system behind Form 4, and how it differs from the crimes in the headlines.
• Not All Insiders Are Equal: Which Roles Produce the Strongest Signals: What 657,511 scored purchases reveal about which job titles are worth following.
• Does Insider Buying Beat the Market?: What a decade of scored Form 4 purchases delivered against the S&P 500.

For informational purposes only. Not investment advice.