Martin Klein has been a lawyer in Hamburg since 1997, he specialized in sales law in the area of investments and insurance. He advises companies and intermediaries on the design of their business processes and, as a litigator, represents financial investment intermediaries and insurance brokers in liability proceedings.

Since February 2007, Klein has been responsible for the intermediary association VOTUM, initially as managing director and now as executive director. In this role, he represents the interests of the advisory financial services industry in Berlin and Brussels and is in dialogue with both the relevant ministries and the parties' specialist politicians as part of the ongoing legislative process. The focus of his advisory work is the company-appropriate implementation of European and German regulatory requirements in sales processes. As a member of the supervisory board of brokerage companies, pools and technology providers, he is also involved in shaping the entrepreneurial future of industry companies. He is also involved as a lecturer at the Schmalkaden University of Applied Sciences in training financial service providers.