Saudi Aramco, Saudi Arabia’s state oil company and the world’s largest for oil production and reserves, has wrapped up its debut in the local sukuk market as part of a push to diversify its funding sources, which has at its core the initial public offering (IPO) of a minority stake in the company.

Saudi Aramco reportedly closed the bookbuilding for its first private placement of a SR11.25bn ($3bn) sukuk bond on April 4, offering investors a yield of 25 basis points over the six-month Saudi Arabian Interbank Offered Rate.

The issuance is part of a programme to raise up to SR37.5bn in the debt market, and a further, undisclosed, amount through the floating of 5% of the company on the stock market.

There is some uncertainty around the real value of the company, whose oil reserves and financial performance have always been somewhat unclear. While Saudi authorities put its value at $2000bn, external observers including the Financial Times estimate its real value is around half that.

Even then, the company would be worth twice as much as Apple, currently the most valuable listed company. Consequently, the Saudi Aramco IPO, expected some time in 2018, would be the largest of its kind ever attempted. It would enable the royal family to raise at least $45bn to $50bn to cover part of Saudi Arabia’s burgeoning fiscal deficit, which totalled SR297bn in 2016, from a record gap of SR367bn or 15% of gross domestic product in 2015.

Saudi Aramco appointed JPMorgan, Morgan Stanley and HSBC as financial advisers for the listing in March, Reuters reported. Earlier in February the company hired New York boutique investment bank Moelis as independent adviser to the IPO.