Markus advises clients on European and German competition law. He spends much of his time defending companies in cartel cases, which may entail very substantial fines that can sometimes pose a threat to a company's financial viability. Markus assists clients with establishing the underlying facts (internal investigations), works with them to develop the most viable defence strategy, and represents them before the European Commission, the German Federal Cartel Office, as well as the European and German courts. Markus has substantial expertise with respect to leniency applications and settlement negotiations, both at a European and German level. Recently, he has been involved in major international cartel investigations pursued by the European Commission, the US Department of Justice, and the Japanese Fair Trade Commission. His track record includes several cases in the auto parts sector (Thermal Systems, Exhausts, Acoustically Effective Components) and the electronic components industry (Electrolytic Capacitors).

Markus frequently advises clients in merger control cases before the European Commission and the Federal Cartel Office, and coordinates merger control approval processes for them world-wide. He assists clients in assessing the merger control risk that their transaction may pose and in developing a strategy for negotiating appropriate risk sharing provisions in their deal. In recent years, Markus has represented clients in various phase 2 investigations in Brussels, including Danfoss (Denmark) in relation to the acquisiton of Eaton's global hydraulics business (headquartered in the US) and innogy in relation to the takeover by E.ON. He also acted for Knorr-Bremse when the company sought to acquire Haldex (Sweden).

Markus provides advice to clients on the rules concerning the abuse of a dominant position and on distribution systems. He also counsels clients more generally with respect to competition law compliance.

Markus advises clients across a range of diverse industries. He has particular expertise in the insurance sector, where he frequently counsels on the specific competition law issues raised in the context of insurance distribution and insurance pools. For many years, he has also assisted insurance companies in merger control proceedings.