Bankers have told the Saudi government that investors will likely value the company at around $1.5 trillion, below the $2 trillion valuation touted by Crown Prince Mohammed bin Salman when he first floated the idea of an IPO nearly four years ago.
Aramco also did not mention what measures it has taken to beef up security following unprecedented attacks on its oil plants in September.
Sources have told Reuters the oil company could offer 1%-2% of its shares on the local bourse, raising as much as $20 billion-$40 billion. A deal over $25 billion would top the record-breaking one of Chinese e-commerce giant Alibaba in 2014.
"Today is the right opportunity for new investors to reap the benefits of Aramco's ability to achieve value, and boost it on the long-term," Aramco Chairman Yasir al-Rumayyan told a news conference at the company's headquarters in the eastern city of Dhahran.
The company will spend the next 10 days talking to investors and sounding out their interest and the price range will follow, he said.
The IPO is designed to turbocharge Prince Mohammed's ambitious economic reform agenda by raising billions to build non-energy industries and diversify revenue streams.
Rumayyan said a decision on an international listing for Aramco shares will be made in the future, without giving a time frame or venue for the overseas listing.
"Selling a small piece of Aramco in a captive market gives the KSA (Kingdom of Saudi Arabia) more control to prop the value of Aramco up over its fair value," said Gary Ross, CEO at Black Gold Investors.
Confirmation of the sale of shares in the oil giant, whose formal name is Saudi Arabian Oil Co, comes about seven weeks after the crippling attacks on its oil facilities, underlining Saudi Arabia's determination to push on with the listing regardless.
Aramco said it does not expect the Sept. 14 attack, which targeted plants at the heart of Saudi Arabia's oil industry and initially halved its production, would have a material impact on its business, operations and financial condition.
Aramco accounted for about one in every eight barrels of crude oil produced globally from 2016 to 2018, it said on Sunday.
Its net income for the third quarter of 2019 amounted to $21.1 billion, according to Reuters calculations, dwarfing the income for the same period of oil giants like Exxon Mobil Corp , which was just over $3 billion.
Rumayyan said the valuation should be determined after the investor roadshow. CEO Amin Nasser told the same news conference that Aramco plans to release the prospectus on Nov. 9.
To help get the deal done, Saudi Arabia is relying on easy credit for retail investors and hefty contributions from rich locals. "Whatever this local round achieves, with domestic players being strong armed into investing, international investors are still going to value this well below the expectations of (Crown Prince) Mohammed bin Salman," said Rory Fyfe, managing director at Mena Advisors.
LURING INVESTORS
The Saudi stock market fell 2% on Sunday after the Aramco announcement. The benchmark index is down nearly a fifth since May as local institutions sold shares to prepare for the Aramco deal, fund managers and analysts say.
Salah Shamma, head of investment, MENA, at Franklin Templeton Emerging Markets Equity, said some local investors could be selling other shares in order to shift investments to Aramco, but this could well be a case of "short-term pain for long-term gain."
To comfort investors, Aramco said on Sunday the state will forgo its right to receive a portion of cash dividends on shares, giving priority to new shareholders.
Aramco is also cutting royalties it pays to the state. Effective Jan. 1, 2020, it will adopt a progressive royalty scheme, with a marginal rate set at 15% up to $70 per barrel, 45% between $70 and $100, and 80% if the price rises higher.
The firm said the Saudi market regulator, which approved the application to list on Sunday, issued an exemption for non-resident institutional foreign investors to subscribe.
Saudi investors would be eligible to receive bonus shares - a maximum of 100 bonus shares for every 10 allotted shares.
At a valuation of $1.5 trillion, Aramco would still be worth at least 50% more than the world's most valuable listed companies, Microsoft and Apple, which each have a market capitalisation of about $1 trillion.