The core activity of the company 'Groupe Z' encompasses a combination of three main areas:
1. **Insurance**: The company offers insurance services, including brokerage (insurance mediation).
2. **Trust Services**: Groupe Z provides trust services, which include administrative and financial management for companies and private individuals.
3. **Real Estate**: The company is also active in the real estate sector, with services likely to include property management, brokerage, or consulting, although the exact services are not specified.
Overall, Groupe Z offers a comprehensive range of services aimed at supporting the administrative and financial management of companies and private individuals.