This chapter reviews the legislation and regulations whose aim is to ensure that the London stock exchange (LSE) is efficient and free of market abuse. It covers the legislation and regulations relating to the disclosure of information to the market. The chapter explores the rules and codes of practice relating to the situation where a listed company is involved in a takeover or merger bid. It suggests that there are many laws and regulations, codes of practice that relate to listed companies affecting the rights of shareholders and the pricing of securities. The listing rules were traditionally set by the stock exchange itself but are now administered by the financial services authority (FSA) and effectively have the force of law. The criminal justice act 1993 (CJA) attempted to block the loopholes in the 1985 Act by extending the classes of individuals who could be regarded as party to the offence.