On 14 August 2019, The Danish FSA issued a guidance No. 9727 on the criminal liability of securities dealers for aiding and abetting a customer’s violation of the prohibitions on market abuse in MAR, notably insider dealing and market manipulation. The guidance declares that the mere execution of the customer’s order is a criminal offence punishable as market abuse. It is argued that this is incorrect and that only activity beyond mere execution will suffice as ai- ding and abetting. The argument is partly based on Danish law, partly on MAR, where especially the obligation on dealers to report any suspicious activity by their custo- mers in MAR Art 16 suggest that the mere execution by them of such orders cannot be illegal in itself. It is further criticised that the FSA issues guidance of matters of crimi- nal law that are uncertain as it will seriously disrupt the business of securities dealers and it is recommended that the guidance is withdrawn or modified.