Goldman Sachs and Citigroup are poised to take a big role in the Saudi Aramco IPO, according to reports. : Goldman Sachs and Citigroup are poised to take a major role in the sale of a portion of Saudi Arabia's state oil giant, which is expected to be the biggest initial public offering ever, according to multiple reports. Saudi Aramco aims to offer investors a 5 percent stake in the company this year. The IPO is central to Crown Prince Mohammed bin Salman's effort to create the world's largest sovereign wealth fund and diversify Saudi Arabia's economy.