SpaceX, Elon Musk’s rocket and satellite company, has filed for what could become the biggest initial public offering ever, outlining plans to raise as much as $75 billion from public investors. If the deal goes ahead on those terms, the company’s market debut would eclipse every previous IPO on record. The filing states that after the offering, Mr Musk would serve as chief executive, chief technology officer and chair of the board. US media reports said SpaceX is seeking to raise $75bn and secure a valuation of up to $1.75…