Form 4

Form 4 is a document that insiders at a company—like executives, board members, or major shareholders—must file with the SEC (the government agency that oversees stock markets) whenever they buy or sell shares of their own company's stock. You'll see these filings published online, usually within a couple of days of the transaction. They matter because insider trading activity can signal whether company leaders believe the stock is undervalued or overpriced, giving retail investors a peek into what the people closest to the business actually think. For example, if a CEO suddenly buys 10,000 shares of her own company, that Form 4 filing might suggest she thinks the stock is headed higher.