Saudi prince Salman, the king’s favored son, has been at it again: three months after telling The Economist of plans to privatize Aramco he has used a lengthy interview with Bloomberg to lay out plans for a $2trn wealth fund.

Saudi Arabia is planning to establish a $2 trillion sovereign wealth fund to help diversify the economy away from oil, Saudi Deputy Crown Prince Muhammad bin Salman told Bloomberg in a five-hour interview that ended at 4am on 31 March.

The 30-year old prince,...