Core Points - The article discusses the regulations governing the reduction of shares by shareholders of Nasdaq-listed companies, particularly focusing on the requirements set by U.S. securities laws and exchange rules [2][4]. Group 1: Lock-up Period and Regulatory Framework - The lock-up period is a fundamental restriction on share reduction following an IPO, typically lasting 180 days, with some exceptions allowing for a shorter duration [2][4]. - Rule 144 outlines the reduction norms for restricted and unrestricted securities, requiring a minimum holding period of 6 months for restricted securities [2][4]. - Section 16 imposes reporting obligations on insiders, including directors and executives, regarding their trading activities [2][4]. Group 2: Insider Trading and Disclosure Requirements - Section 10(b)-5 prohibits shareholders from trading based on material nonpublic information, constituting insider trading [3][4]. - Insiders must return profits from short-swing transactions, defined as buying and selling within a 6-month period [2][4]. - Form 4 must be submitted within 2 business days after each transaction, detailing the transaction date, price, quantity, and changes in holdings [6][4]. Group 3: Affiliate Restrictions and Reporting Obligations - Affiliates, defined as shareholders with control relationships, face stricter limitations on share reductions, including adherence to Rule 144 and Section 16 reporting obligations [6][4]. - Schedule 13D/G requires shareholders owning more than 5% of a company to update their filings when their holdings change by more than 1% [6][4]. Group 4: Special Cases and Foreign Shareholder Requirements - Block trades allow large shareholders to sell significant amounts of shares without drastically impacting market prices, subject to Nasdaq's price fluctuation limits [4][6]. - Foreign shareholders must comply with FATCA and CRS regulations, disclosing their U.S. securities holdings and potentially facing withholding tax on U.S. source income [4][6].