European investment firm Groupe Bruxelles Lambert SA is nearing a deal to buy health-care services firm Affidea from Switzerland’s richest person Ernesto Bertarelli, according to people familiar with the matter.

A deal could be announced this week after GBL, as the Belgium-based holding company is known, outbid rivals including industry players and private equity firms, the people said, asking not to be identified because the matter is private. A purchase could value the Netherlands-based company at about 1.6 billion euros ($1.7 billion), the people said.

Listed on the Brussels stock exchange for more than 60 years, GBL had a net asset value of 22.5 billion euros at the end of December. Its shares have slid 4.5% this year, valuing the firm at about 14.7 billion euros.

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