Understanding Section 16 filing requirements is essential for public company insiders – officers, directors, and 10% beneficial owners. To comply with SEC regulations and maintain transparency, insiders must submit mandatory ownership reports on Forms 3, 4, and 5 via EDGAR. Form 3 establishes initial ownership within 10 days, Form 4 reports changes in shares within two business days, and Form 5 covers year-end disclosures. Learn the key obligations and deadlines to prevent non-compliance penalties.