Dirk Opstelten

HAL Allergie GmbH manufactures allergy vaccines and diagnostics products. The firm offers immunotherapies. The company was founded in 1977 and is headquartered in Dusseldorf, Germany.

Droege Group AG provides consultancy and investment services. It directly invests with own equity in corporate subsidiaries and medium-sized companies. It focuses on spin-offs, underperformers, turnarounds, and successions. The company was founded by Walter P. J. Droege in 1988 and is headquartered in Duesseldorf, Germany.

Trenkwalder International AG provides human resources consulting services. It offers temporary staffing, payroll, onsite management, training, and outplacement and personnel consultancy services. It conducts operations in Germany, Hungary, Slovakia, Slovenia, Czech Republic, Croatia, Serbia, Greece, Macedonia, Montenegro, Bosnia, Rumania, Poland, Bulgary, Turkey, Albania, Liechtenstein and Switzerland. The company was founded by Richard Trenkwalder in March 1985 and is headquartered in Vienna, Austria.

Droege Capital GmbH (Droege Capital) is the private equity subsidiary of Droege & Co. International Group AG, a family-owned and entirely equity-financed firm based in Germany which was founded by Walter P. J. Droege in1988 as Droege & Co. International Management Consultants. Formerly known as DIC Capital, Droege Capital is based in Dusseldorf. They invest directly in corporate spin-offs or businesses in turnaround situations, aiming to guide their investee companies through the restructuring process and provide ongoing support during the subsequent strategic development phase.

Trenkwalder Beteiligungs GmbH provides acquisition and asset management services. The private company is based in Vienna, Austria.

Dr. im Brahm Immobilienverwaltung GmbH & Co. KG manages land, buildings, and apartments. The private company is based in Dusseldorf, Germany. The CEOs of the German company are Walter P. J. Droege, Hedda im Brahm-Droege.