Established in 2014, PrimeStone takes substantial stakes in European listed companies that it believes have significant potential for value creation.

PrimeStone was founded by three former partners from The Carlyle Group, who specialized in buyouts and have invested and worked together across Europe for more than 15 years. They all also share a prior experience as consultants in strategy and operational improvements with The Boston Consulting Group.


PrimeStone has a strategy of constructive and active management in mid-sized listed European companies that have significant value creation potential through strategic, operational or financial improvement. PrimeStone creates value by taking a long-term perspective, adopting an active approach and having a significant influence over its underlying investments through a constructive dialogue with boards and management teams.

Mérieux Développement works alongside entrepreneurs whose products and services can bring genuine advances to the health of patients and consumers worldwide. Merieux Developpement is the investment arm of Institut Mérieux, which employs 15,000 people worldwide and generated revenues in excess of USD 3 billion in 2017.

Sienna Capital & Primestone

As part of a long-term agreement, Sienna Capital invested EUR 150 million in February 2015. In exchange for its support of PrimeStone, Sienna Capital benefits from certain favourable financial terms.

Financial year 2017

In 2017, PrimeStone completed 2 new investments.


Value of investment

EUR 176 million (30/06/2018)

Business area

European equities

Registered office

London, UK

Key data from GBL Annual Report 2017