What is an Insider Filing?
A guide to SEC Form 4 and other insider transaction disclosure forms.
What is an Insider Filing?
Insider filings are SEC disclosures made by corporate insiders — directors, officers, and large shareholders — when they buy or sell shares of their company's stock.
The primary form is Form 4, filed within 2 business days of a transaction.
Who is an "Insider"?
Under SEC rules, insiders include:
- Officers — CEO, CFO, COO, General Counsel, and other named executive officers
- Directors — Board members
- 10% shareholders — Any individual or entity owning more than 10% of a class of equity securities
Form 4: The Main Insider Filing
Form 4 must be filed within 2 business days of a transaction. It discloses:
| Field | Description |
|---|---|
| Insider name and title | Who made the transaction |
| Transaction date | When it occurred |
| Security type | Common stock, options, etc. |
| Transaction code | Buy (P), Sell (S), award (A), etc. |
| Shares transacted | How many shares |
| Price per share | At what price |
| Shares owned after | Total holdings after transaction |
Transaction Codes
| Code | Meaning |
|---|---|
| P | Open-market purchase |
| S | Open-market sale |
| A | Award / grant |
| D | Disposition (non-sale) |
| F | Tax withholding on vesting |
| M | Option exercise |
| G | Gift |
What Matters Most: Open-Market Purchases
The most significant insider transactions are open-market purchases (code P) — when an insider uses their own money to buy shares at market price. This is considered a strong signal of confidence.
Less meaningful:
- Option exercises (M) — insiders must exercise options before they expire
- Tax withholding sales (F) — automatic, not discretionary
- Award grants (A) — compensation, not investment decisions
Other Insider Forms
| Form | Purpose |
|---|---|
| Form 3 | Initial ownership filing when becoming an insider |
| Form 4 | Ongoing transaction disclosures |
| Form 5 | Annual report of exempt transactions |
| Schedule 13D | Disclosure when acquiring >5% with intent to influence |
| Schedule 13G | Passive acquisition of >5% |
InvestorLens and Insider Data
InvestorLens currently uses a proxy for insider scores in the AI Infrastructure section. Direct Form 4 integration is planned for a future update, which will pull real insider transaction data for all 20 tracked AI infrastructure companies.
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