Satya Nadella became CEO of Microsoft in 2014, successfully transforming the company by shifting its focus from a stagnant mobile strategy to cloud computing and other innovative technologies. He diagnosed internal issues, such as a toxic corporate culture and poor employee morale, and implemented major changes including a new performance review system and prioritizing customer obsession. Under his leadership, Microsoft saw a significant increase in stock value and market share, although challenges remain from competitors like Amazon in the cloud market.