Thomas Russo has left Gilead Sciences (NASDAQ: GILD) to become chief financial officer of Assembly Biosciences (NASDAQ: ASMB). Russo held a number of positions during his seven years at Gilead, and was most recently vice president and head of commercial finance. His experience also includes posts at Robert W. Baird & Co. and Merck (NYSE: MRK). Russo’s new job reunites him with John McHutchinson, the longtime-Gilead executive who was named Assembly Bio’s CEO in August. South San Francisco-based Assembly Bio is developing treatments for hepatitits B viral infection and microbiome-associated diseases.