Market abuse

In economics and finance, market abuse may arise in circumstances in which investors in a financial market have been unreasonably disadvantaged, directly or indirectly, by others who:

have used information which is not publicly available
have distorted the price-setting mechanism of financial instruments
have disseminated false or misleading information

Market abuse is split into two different aspects :

Insider dealing: where a person who has information not available to other investors makes use of that information for personal gain
Market manipulation: where a person knowingly gives out false or misleading information in order to influence the price of a share for personal gain

In 2013/2014, the EU updated its legislation on market abuse, and harmonised criminal sanctions. In the 2015 Danish European Union opt-out referendum, the Danish population rejected adoption of the 2014 market abuse directive and much other legislation.
In the UK, the market abuse directive was implemented in 2003 to reduce market abuse. It applied to any financial instrument admitted to trading on a regulated market or in respect of which a request for admission to trading had been made. MAD was subsequently replaced by the Market Abuse Regulation in 2016.