When an insider voluntarily buys their company's stock on the public exchange using their own capital.
Definition
An open-market purchase is a transaction where a corporate insider actively goes to the public stock market (via a broker) to buy shares of their own company at the current market price, paying with their own funds.
Why it matters for Whale Tracking
This is the highest-conviction bullish signal available. As the Wall Street adage goes: 'Insiders might sell their shares for any number of reasons—buying houses, paying taxes, diversifying—but they buy them for only one: they think the price will go up.'
Real-World Example
"A Form 4 transaction coded with a 'P' indicates an open-market purchase. If the CEO of Nvidia (NVDA) voluntarily buys $5M worth of shares, it shows personal conviction, unlike shares merely granted as compensation."