In the US, the Securities and Exchange Commision (SEC) disseminates regulatory filings using the EDGAR system, which stands for Electronic Data Gathering, Analysis and Retrieval. This is used to automatically collect, validate, index, accept and forward form submissions by SEC-regulated entities.
Within this system, the Form-4 filing is the "statement of changes in beneficial ownership of securities." It is the form used to report legal insider trading. Insiders must file a Form-4 within two business days of acquiring or disposing of company securities. Every company director and officer is required to report trades in this way. Additionally, any person owning more than 10% of a class of equity securities must also file.
For a while, Greg Harris, who used to develop quantitative trading strategies for Black River Asset Management and is now completing a PhD in Computer Science, was the fastest Form-4 trader on the block. Here, he discusses his trading strategy.