The bull run in Microsoft's stock this past year has helped the tech giant surpass Exxon Mobil and seize the rank of the second most valuable company, behind Apple Inc. Under new CEO Satya Nadella, Microsoft has worked to overcome its reputation as a clumsy behemoth struggling to keep up with new tech trends and consumer habits. Nadella has cut expenses and jobs while pledging to refocus the company on mobile technology and cloud computing.