1. In the case of a transferable security within the meaning of Article 4(1)(44)(a) of Directive 2014/65/EU, an emission allowance or a unit in a collective investment undertaking, the most relevant market in terms of liquidity for that financial instrument (the most relevant market) shall be determined once each calendar year on the basis of the data of the previous calendar year, provided that the financial instrument was admitted to trading or traded at the beginning of the previous calendar year, as follows:

(a) for instruments admitted to trading on one or more regulated markets, the most relevant market shall be the regulated market where the turnover, as defined in Article 17(4) of Commission Delegated Regulation (EU) 2017/587 [Commission Delegated Regulation (EU) 2017/587 of 14 July 2016 supplementing Regulation (EU) No 600/2014 of the European Parliament and of the Council on markets in financial instruments with regard to regulatory technical standards on transparency requirements for trading venues and investment firms in respect of shares, depositary receipts, exchange-traded funds, certificates and other similar financial instruments and on transaction execution obligations in respect of certain shares on a trading venue or by a systematic internaliser (see page 387 of this Official Journal).] for the previous calendar year for that instrument is the highest;

(b) for instruments not admitted to trading on regulated markets, the most relevant market shall be the MTF where the turnover for the previous calendar year for that instrument is the highest;