Sometimes the key to a deal’s success happens far from the financial markets and outside the public gaze, as Covington & Burling’s Mark Plotkin (seated) and David Fagan showed while steering Global Foundries Inc. through its $1.5 billion acquisition of IBM’s semiconductor unit.

It was a tough sell: Owing to GlobalFoundries’ ties to the Abu Dhabi government—the emirate’s ruling family indirectly owns the company—and the IBM unit’s role as a trusted supplier of chips to the U.S. military, the acquisition prompted one of the most complex reviews in memory by the Committee on Foreign Investment in the United States.