State-owned oil company Saudi Aramco said on Sunday it has exercised its "greenshoe option" to sell an additional 450 million shares, raising the size of its initial public offering (IPO) to a record $29.4 billion. Aramco initially raised a then-record $25.6 billion in its IPO in December by selling 3 billion shares at 32 riyals ($8.53) but indicated it may sell additional shares through the over-allotment of shares.

A greenshoe option, or over-allotment, allows companies to issue more shares in an IPO when there is greater demand from participants during the initial offering. Investors were allocated the additional shares for the option during the book-building process, Aramco said.

Aramco said "no additional shares are being offered into the market today and the stabilising manager will not hold any shares in the company as a result of exercise of the over-allotment option."

Aramco shares have been volatile recently because of geopolitical concerns as tensions between the United States and Iran rose after President Donald Trump ordered a drone strike that killed a top Iranian commander and raised fears of war. Shares of Aramco fell to 34 riyals on Jan. 8, its lowest since the stock began trading on Dec. 11, but closed at 35 riyals on Thursday.

Thursday's closing price valued Aramco at $1.87 trillion, above the IPO price, which valued the company at $1.7 trillion, but below Crown Prince Mohammed bin Salman's coveted $2 trillion target.