The Document That Tells You Everything
Every time a corporate insider buys or sells shares, they have to tell the SEC about it within two business days. The document they file is called a Form 4. It’s free. It’s public. And once you know how to read one, you have access to the same information that institutional trading desks use to track smart money.
Most investors have never looked at a Form 4 in their life. That’s a mistake. Let’s fix it.
Where to Find Form 4 Filings
The primary source is SEC EDGAR, the Electronic Data Gathering, Analysis, and Retrieval system. It’s the SEC’s public filing database and it’s completely free to use.
You can search by company name, ticker symbol, or the insider’s name at sec.gov/cgi-bin/browse-edgar. Filter for Form 4 filings and you’ll see every insider transaction for that company in reverse chronological order.
There are also aggregator services that pull this data and present it in cleaner formats. But the raw filing on EDGAR is the source of truth. If something looks off on any third-party site, always go back to the original Form 4.
Anatomy of a Form 4
A Form 4 has two main tables, and a few header fields that matter. Let’s walk through each piece.
The header tells you who filed and for which company. You’ll see the insider’s name, their relationship to the company (officer, director, 10% owner), and the company name plus ticker. Pretty straightforward.
Table I covers transactions in equity securities of the issuer. This is where the action is. Each row represents a single transaction, and the columns that matter are:
- Transaction Date tells you when the trade happened. Not when it was filed. When it was executed.
- Transaction Code is a single letter that tells you what type of transaction occurred. P means purchase on the open market. This is the one you care about most. S means sale. A means award or grant. M means option exercise. There are others, but P is the signal.
- Shares tells you how many shares were involved.
- Price Per Share tells you the average price paid.
- Shares Owned Following Transaction shows the insider’s total position after the trade.
Table II covers derivative securities like options and warrants. Unless you’re specifically tracking option exercises, you can mostly skip this table for insider buying research.
Transaction Codes: What Actually Matters
The transaction code is the single most important field on the entire form. Here’s your cheat sheet:
- P (Purchase): Open-market buy. This is the signal. Real money, voluntary decision.
- S (Sale): Open-market sale. Ambiguous for the reasons we discussed earlier.
- A (Award/Grant): Shares given as compensation. Not a market signal.
- M (Exercise): Option exercise. Often confused with open-market buying. It’s not the same thing. An executive exercising vested stock options is collecting compensation, not making a market bet.
- G (Gift): Shares given away. Usually tax planning.
- F (Tax Withholding): Shares surrendered to cover taxes on vesting RSUs. Routine.
If the transaction code isn’t P, it’s not an open-market purchase. Period. This trips up a lot of people, especially with screeners that sometimes lump option exercises in with genuine buys.
Direct vs. Indirect Ownership
Each transaction row also shows whether the ownership is direct (D) or indirect (I).
Direct ownership means the insider holds the shares in their own name. Simple.
Indirect ownership means the shares are held through a trust, a family member’s account, an LLC, or some other entity that the insider controls. You’ll see footnotes like “Shares held by the Smith Family Trust” or “Shares held by XYZ Holdings LLC.”
Both count. An insider buying through their family trust is still an insider buy. The indirect route is often just estate planning or asset protection. Don’t discount it.
Multiple Transactions in a Single Filing
This catches people off guard. A single Form 4 can contain multiple transactions. An insider might execute three separate buy orders on the same day at slightly different prices. Each one shows up as a separate row in Table I.
When you see this, you want to look at the aggregate picture. Total shares purchased across all rows. Weighted average price. Total dollar amount committed. A filing that shows five separate purchases of 10,000 shares each at prices between $14.20 and $14.55 is really one decision to buy 50,000 shares. The execution just got split up.
About a third of all Form 4 buy filings contain multiple transactions. If you’re only looking at the first row, you’re underestimating the size of the commitment.
What to Focus On
When you’re scanning Form 4 filings for genuine insider buying signals, here’s your filter:
Look for transaction code P. Everything else is noise for this purpose.
Look at who’s buying. The CEO or CFO buying carries far more weight than an outside director. The C-suite has the deepest visibility into operations. A director who attends four board meetings a year knows a lot less.
Look at the dollar amount. A CEO buying $50,000 worth of stock is a rounding error for someone making $15 million a year. A CEO buying $500,000 or more is putting meaningful personal capital at risk. Size matters.
Look at the price. Compare the insider’s purchase price to where the stock is currently trading. If they bought at $25 and the stock has fallen to $22, you might be looking at an opportunity. If the stock has already run to $35, the easy money may have already been made.
Check for clusters. Is this the only insider buying, or are multiple insiders filing Form 4s around the same time? Clusters are the strongest signal. We’ll cover that in detail next.
What to Ignore
Option exercises (code M) that get sold immediately. This is just an executive cashing in their compensation. Don’t confuse it with conviction.
Small purchases by directors under $25,000. Board members sometimes make token purchases to meet minimum ownership requirements. Not a signal.
10b5-1 plan transactions. These are pre-scheduled trades set up weeks or months in advance. They tell you nothing about current sentiment. The Form 4 footnotes will usually mention if a transaction was made under a 10b5-1 plan.
Once you can read a Form 4 quickly and separate the real buys from the noise, you’re already ahead of most retail investors. The filing is dry. The information inside it is anything but.