State-owned oil giant Saudi Arabian Oil Co., or Saudi Aramco, plans to exercise its 15% greenshoe option in full or in part in the first 30 days of its trading period, Reuters reported Dec. 10, citing a statement from its lead managers.

Saudi Aramco shares will begin trading on the Saudi stock exchange Dec. 11.

Reuters said that if Aramco exercises the option in full, it could raise $29.4 billion. Greenshoe options allow the underwriter to sell more shares than initially planned if the demand for a share offering proves higher than expected.

Saudi Aramco priced its initial public offering at 32 Saudi riyals per share at the top of its expected range, making it the world's largest IPO with its 1.5% offering raising $25.6 billion, beating Chinese e-commerce giant Alibaba Group Holding Ltd.'s $25 billion listing in 2014.

As of Dec. 9, US$1 was equivalent to 3.75 Saudi riyals.