MCM, now bought out by Marex Capital Markets, became embroiled in a long-running tax scandal relating to £20m in wrongful tax reclaims and a lack of oversight of cum-ex trading related to withholding tax.

The broker provided advice on securities to investors and created a fee structure which meant that clients were able to reclaim withholding tax from the Danish Tax Authority (SKAT).

A direct consequence of these breaches was illegitimate payments in excess of £20m being paid by the Danish Tax Authority to clients of MCM.

Between February 2012 and March 2015 MCM enabled significant volumes of dividend arbitrage trading on behalf of clients, allowing clients to make withholding tax reclaims.