Mathematician, writer, and banker.
Received as an avocat and doctor of law. Professor of physics and mathematics at the Académie de Genève (1752-1760). A longtime friend of d’Alembert, he wrote various articles on physics for the Encyclopédie. Named a corresponding member of the Académie française (1756). Was forced to vacate his position at the Académie de Genève (1760) and was succeeded by Horace-Benedict de Saussure. Established as a merchant in Marseilles with the firm of Peschier, Necker & Cie. (1762). Member of the Académie de Marseilles (1766). Went to Paris. Partner in the firm of Germany, Girardot & Cie., which became Girardot, Haller & Cie. in 1777.
Elder brother of Jacques Necker. Married (1) in 1752 to Isabelle André (d. 1759); (2) in 1777 to Catherine Cannac.