Saudi Aramco plans to list 1% of its shares on the Riyadh Stock Exchange by the end of 2019 and another 1% in 2020, sources familiar with the matter have told Reuters newswire.

News update: The drone attacks of September 15 on Aramco's oil facility in Abqaiq about 37 miles southwest of Dhahran in Saudi Arabia's eastern province may impact Aramco’s valuation but are unlikely to derail the kingdom’s plan to sell shares in the oil giant, according to the Eurasia Group.

“The thinking now is to list 1% this year, and another next year. This will be easier for the stock market to absorb. The smaller the target liquidity, the easier and the sooner the local IPO will be,” said a source, adding that the listing would be open to qualified foreign investors.

Aramco is preparing to sell up to 5% equity by 2020-2021, in what could be the world’s biggest initial public offering (ipo).

However, as Aramco prepares for the ipo, drones attacked the Kingdom’s oil facilities on Sept. 15, setting alight the world’s biggest crude-processing plant. The Eurasia Group, a US-based political risk research and consulting firm, said while the attacks might impact Aramco’s valuation, they were unlikely to derail the Kingdom’s plan to sell shares in the oil giant.

“Crown Prince Mohammad bin Salman will push the company to demonstrate that it can effectively tackle terrorism or war challenges,” analysts led by Ayham Kamel, Eurasia’s head of Middle East and North Africa research, said in a report. “The attacks could complicate Aramco’s ipo plans given rising security risks and potential impact on its valuation.”

Sources said Aramco has selected banks for the share sale and may list as soon as November.

The removal earlier this month of Saudi Arabia’s energy minister Khalid al-Falih as chairman of Aramco was seen as a sign that the oil group was inching closer to thee long-awaited stock listing. Shortly after losing his chairman role, Al-Falih was also replaced as energy minister. Al-Falih was reported to be unenthusiastic about the ipo.