BP has returned to its oil and gas roots in a spectacular about-turn following its trailblazing attempt five years ago to become a renewables giant. The takeaway for Big Oil is that the energy transition is a marathon,

BP has abandoned a radical attempt to reinvent itself as a green energy company, bowing to pressure from investors after its aggressive shift away from fossil fuels over the past five years backfired.

But BP has struggled to reduce its debt load and the moves have failed to ignite its share price, leading to speculation among bankers that a rival could swoop in for parts—or t