He founded the trading house Moses & Søn G. Melchior.

He first visited Copenhagen in about 1750 to establish connections for his merchant father and moved there on a permanent basis in 1760.

For the first 20 years he dealt mainly with tobacco from the Netherlands and Bremen, partly in partnership with his brother-in-law Akiba Jakobsen.

He later founded the trading house Moses & Søn G. Melchior.

By 1790 he traded on the Danish West Indies.