Every officer and director who buys or sells their own company's stock has to tell the SEC within two business days. Those filings are public. The Insider tab pulls them in.

The trick is knowing which trades carry signal and which are noise. Insiders — officers, directors, and 10%+ shareholders — file Form 4 when they trade their company's stock. The data is structured, machine-readable, and available within 48 hours of the trade.

The signal value depends entirely on the type of trade. Insiders sell for many reasons that have nothing to do with their view of the business: tax obligations, divorce, scheduled diversification, college tuition, buying a house. Insiders buy for essentially one reason: they think the stock will go up.

Academic studies consistently find insider buying carries far stronger predictive power than insider selling — because the noise-to-signal ratio is much lower on the buy side.