Nikola Confronts Future of Doubts on Chair Exit, Stock Drop (1)

Nikola Corp. faces an uncertain future following the sudden departure of its founder and chairman in the wake of regulatory probes and a collapse of its stock price, even as partner General Motors Co. said it won’t abandon the electric-truck startup.

Trevor Milton stepped down as executive chairman effective immediately and was replaced by Stephen Girsky, the former GM vice chairman who oversaw Nikola’s stock listing and helped broker their partnership. Nikola’s shares -- already reeling from claims of deception leveled by short seller Hindenburg Research -- plunged as much as 30% at one point, its steepest drop ...