What is the best source for obtaining information on insider purchases?

Form 4 is the best source for obtaining information on insider purchases because it is specifically designed to report changes in ownership of a company’s securities by its insiders, which include executives and board members. This form must be filed with the Securities and Exchange Commission (SEC) whenever an insider buys or sells shares in their company, making it a timely and detailed source of information.

Form 4 provides insight into the actual transactions that insiders are making, including the number of shares purchased or sold, the date of the transaction, and the price at which it occurred. This can be particularly valuable for investors and analysts who monitor insider activity to gauge the sentiment and potential confidence of a company's leadership regarding its future performance.

While other forms like the 10-K and 13D contain useful information, they do not focus specifically on the buying and selling activities of insiders. The 10-K is an annual report providing a comprehensive overview of a company’s financial performance, while Form S-1 is a registration statement for new securities and does not track insider transactions. Form 13D is concerned with beneficial ownership and significant shareholders, rather than day-to-day insider transactions. Therefore, Form 4 is the most reliable and direct source for tracking insider purchases.