When an insider voluntarily liquidates shares of their company on the public exchange.
Definition
An open-market sale occurs when an insider actively decides to sell their existing company shares to the public market at the current trading price. On a Form 4 filing, this is typically denoted by the transaction code 'S'.
Why it matters for Whale Tracking
While open-market sales can indicate bearish sentiment, they must be contextualized. A founder selling 2% of their holdings for estate planning is noise. However, multiple executives liquidating significant percentages of their portfolios right before an earnings report can be a red flag.
Real-World Example
"An executive at Tesla (TSLA) executing an open-market sale of 50% of their total vested shares unprompted by a 10b5-1 plan would heavily skew the stock's net capital flow metric into the negative."