Entered family's New York mercantile firm as a teenager and eventually settled in England. Contracted to provide goods for American troops in the Seven Years’ War. Acted as an agent for a group of Pennsylvania fur traders (including his brother David) who sought government compensation for their losses in the war. With several family members and business associates, petitioned to purchase a vast tract of land in western Virginia (1769).
Son of Jacob Franks, a prominent Jewish merchant in New York, and his wife Abigail Levy. Married his English cousin Phila Franks (1765); they had one daughter.