OpenAI’s recent blockbuster deals have added a new layer to its complicated ownership structure, leading to more uncertainty over when and how its powerful shareholders will get an eventual payout.The start-up became the world’s most valuable private company this month, surging to a $500bn valuation on the back of a major share sale, in between striking multibillion-dollar deals with chipmakers Nvidia and AMD.Those deals will help the lossmaking group realise its ambition to deploy $1tn in compu...