Saudi Aramco, with its 12mn b/d production, is the world’s largest oil company. But how big? Its value has been intensely debated since IPO plans were unveiled in April 2016. Estimates have diverged widely. But until decisions are reached on key aspects of the floatation, the firm’s ultimate value remains anyone’s guess.

Ever since the plans for listing a 5% stake of prized state oil giant Saudi Aramco were announced last year, it has repeatedly been heralded as the...