The European Securities and Markets Authority wrote a letter to the European Commission to note its concern that certain investment firms currently operating broker­crossing networks may be seeking to circumvent requirements under the Markets in Financial Instruments Directive II that if they operate an internal matching system and execute client orders on a multilateral basis, such system needs to be authorized as a trading venue. ESMA says some investment firms may be trying to exploit an apparent loophole in regulatory requirements by setting up networks of interconnected systematic internalizers to cross third­party buying and selling interests through principal trading, or other back­to­back trading. ESMA says it is monitoring this activity and may issue questions and answers in the future to clarify the permitted activities of systematic internalizers.