U.S.-Russia Tensions Catch Up With Metals Tycoon Oleg Deripaska

Proximity to President Vladimir Putin helped billionaire but is now a liability

Last fall, Oleg Deripaska ramped up Russia’s presence in Western markets when he pulled off London’s second-biggest corporate listing of the year. Now the metals billionaire is on a U.S. sanctions list and that firm has lost roughly half its value.

The reversal of fortune reflects the arc of the Kremlin’s efforts to build political and financial relations with the West over the past two decades.

Mr....