A Multilateral Trading Facility (or MTF) is a specific type of European financial trading system. The concept was introduced within the Markets in Financial Instruments Directive (MiFID), a European financial law, and describes a trading venue that brings together buyers and sellers in a non-discretionary way according to a defined set of rules resulting in trades.
Additional meaning of Multilateral Trading Facility:
MTFs have been described as a form of "exchange lite" because they provide similar or competing trading services and have similar structures, such as rulebooks and market surveillance departments.
Market operators also act as an arbiter for securities. Companies that wish to list upon an exchange undergo a listing process and pay fees; this allows the operator to ensure that only appropriate securities are available for trading. This may involve requirements about the number of shares that are available, standards around how the accounts of the company are maintained or strict rules about how news is released to the market.
Whether or not a security has been "admitted to trading on a regulated market" is a key concept within MiFID, and is fundamental in how the rules apply to trading in the security. MTFs do not have a listing process and can not change the regulatory status of a security.