Corporate insiders (officers, directors, 10%+ owners) must report trades in their own stock to the SEC on Form 4, usually within two business days. DISC denotes a discretionary open-market transaction — the strongest signal class, since it's a choice rather than a scheduled plan. Each row's score feeds the composite signal engine: positive = accumulation signal, negative = distribution. Sourced directly from SEC filings at scan time; value/share fields are “—” when the filing doesn't disclose them.