Barra’s responsibilities at Walgreens Boots Alliance (WBA), the $117 billion drug store juggernaut (No. 37 on the 2017 Fortune Global 500), are vast. Under her purview as co-COO is the $22.5 billion Pharmaceutical Wholesale Division, which saw its revenues nearly double in 2016, and the 2,000 overseas stores that comprise WBA’s international division. She has also been managing WBA’s $5 billion acquisition of Rite Aid and the company’s partnership with wholesaling giant AmerisourceBergen, in which WBA has a 23.9% stake. Barra, an Italian who trained as a pharmacist, got her start in the drug store business decades ago, running her own shop. It was acquired by Stefano Pessina the man who is now her partner and the CEO of WBA.