Saudi Aramco plans to issue a $10 billion bond as early as next week to help fund its acquisition of a majority stake in Saudi Arabia’s petrochemicals firm, people familiar with the matter said, shining a light on the financial performance of the world’s largest oil company for the first time. The bond would be the first-ever debt issuance by Saudi Arabian Oil Co., as the oil giant is officially known. The money would be used for a down payment on its $69.1 billion purchase of 70% of Saudi Basic Industries Corp., with…