A German boutique with two partners and a total of 15 employees has been brought in to advise General Motors on the sale of carmakers Opel and Vauxhall – one of the highest-profile and most complex deals of the year – highlighting the growth of independent advisory companies in global mergers & acquisitions.

Freitag & Co, which operates out of a small office in Frankfurt, has been drafted in by the struggling automotive giant to seek potential investors for its European business in the Middle East. Their appointment is one of the most striking examples to date of boutiques picking up mandates on the biggest M&A deals. In January, US boutique Evercore was named adviser to pharmaceutical group Wyeth on its $64.5bn (€46.2bn) acquisition by peer Pfizer. US boutique Greenhill & Co is sole financial adviser to Swiss pharma group Roche on its $47bn acquisition of US peer Genentech.