Saudi Arabia’s state-owned energy company has told J.P. Morgan,HSBC and Morgan Stanley they will be the lead underwriters for its planned initial public offering, set to be the largest ever, according to people familiar with the matter. The three banks will lead the giant offering of about as much as 5% of Saudi Arabian Oil Co., known as Saudi Aramco, the people said.  The three banks declined to comment. A spokesperson for Aramco said the firm doesn’t comment on rumor or speculation.