Markus acts for clients in disputes before state courts and in arbitration proceedings. His focus is on complex disputes requiring strategic thinking and persistence as well as in cross-border disputes. Clients seek his advice in bet-the-company disputes.

In recent years, Markus has represented numerous clients in a variety of industries, frequently with multibillion claims at stake. These large scale disputes are typically in the areas of corporate, capital markets, banking and finance law, and IT/IP.

Markus has many years' experience acting as counsel to parties in domestic and international arbitrations. He sits as arbitrator where the common subjects of arbitration are post-M&A disputes, infrastructure projects and distribution arrangements.

Domestic and international publications list Markus in the top group of their dispute resolution rankings referring to him as "one of the best litigators in Germany, if not the best" (Chambers Global).