Insider Trading
Buying or selling a company's stock by company insiders with access to material non-public information. Legal when disclosed; illegal when based on…
Insider Trading refers to the buying or selling of a company's stock by company insiders (executives, directors, large shareholders) who have access to company information. Legal insider trading is disclosed in SEC Form 4 filings; illegal insider trading uses material non-public information (secrets).
Formula
Insider Activity = Net (Buys - Sells) of a Stock by Insiders Over a Period
Tracked via Form 4 filings required within 2 business days of transactions.
Example
A CEO of Apple (AAPL) legally buys $1 million of AAPL stock with her personal funds and files a Form 4. This is legal and shows confidence in the company. If the CEO instead sold AAPL based on advance knowledge of a disastrous earnings miss before it was announced, that would be illegal insider trading (prosecuted by the SEC).
How to Interpret It
- Net insider buying: Executives are buying their own stock, often signaling confidence in future performance. Bullish indicator.
- Net insider selling: Executives are selling stock, possibly for personal reasons (college tuition, house purchase) or pessimism. Less conclusive than buying.
- CEO buying: Especially meaningful because the CEO usually has the most conviction and information.
- Board director selling: May be less informative because board members have less day-to-day knowledge.
- Patterns: Consistent insider buying across multiple executives is more bullish than isolated buys.
Limitations
- Insider selling doesn't always indicate pessimism; executives diversify, pay taxes, or need liquidity for personal reasons.
- Insiders are often required to sell shares to exercise options or meet tax obligations, making selling non-indicative.
- Illegal insider trading (unreported) is invisible until prosecuted by the SEC, which can take years.
- Rule 10b5-1 plans allow insiders to set up automatic trading rules, removing timing discretion and making activity less informative.
Related Terms
- Form 4 — SEC filing reporting insider transactions
- Material Non-Public Information — company secrets that could affect stock price
- SEC Filings — regulatory documents filed by public companies
- Form 144 — SEC filing for sale of restricted securities by insiders