Article 2(1)(45) of MiFIR defines liquidity fragmentation as a situation in which:

(a) participants in a trading venue are unable to conclude transactions with one or more other participants in that venue because of the absence of clearing arrangements to which all participants have access to; or

(b) a clearing member or its clients would be forced to hold their position in a financial instrument in more than one CCP which would limit the potential for the netting of financial exposures.