DHAHRAN, Saudi Arabia — The Kingdom of Saudi Arabia officially launched its initial public offering (IPO) for its state-owned oil company Saudi Aramco on Sunday, announcing that a domestic listing will happen in December. The kingdom's market regulator approved the listing early Sunday but exact details surrounding the size and scope of the IPO remain unknown. In a statement from Saudi Aramco, the company said "the final offer price, number of shares to be sold and percentage of the shares to be sold will be determined at the end of the book-building period." Amin Nasser, president and chief executive of Saudi Aramco, said in a statement that the company's vision "is to be the world's pre-eminent integrated energy and chemicals company." "Our mission is to provide our shareholders with long-term value creation through crude oil price cycles by maintaining our pre-eminence in oil and gas production, capturing additional value across the hydrocarbon value chain and profitably growing our portfolio," he said. In a follow-up press conference on Sunday, Nasser said the company's IPO prospectus would be released on November 9 and told CNBC that the listing of Aramco was to help diversify the economy, and was a way to strengthen the domestic Tadawul exchange by attracting both domestic and international investment. "For us, as Saudi Aramco, I think we are proud of the listing of Aramco. It will increase our visibility internationally. We are a very strong company. By sharing a lot of information, as required by any listed company, there will be a lot of analysts that will review our data and compare it with other listed companies, and we would love to have that kind of comparisons, because we are a company that are proud of our results," he said.

Also at the press conference, Aramco's Chairman Yasser al-Rumayyan said the international listing would be decided on "going forward." He also said he could not comment on the valuation of the company, or the percentage to list. He told CNBC that the company was a safe bet for investors despite some concerns over the security of Saudi oil infrastructure following a drone and missile attack on Aramco facilities in September. "We have also the resilience of the company, and it was really demonstrated in the September 14th attacks ... We have one eighth of the oil production in the world, and the oil traders, they saw this as a one-off event, and that means it is really safe. That's what the money is saying. So the safety, I think the whole wide world it's not only Saudi Arabia, will be looking after the safety of this region and this company," he said. Previous reports have suggested the kingdom will list 1% to 2% of Aramco on its local stock exchange, and then list another slice on an international exchange at a later date — with a total public sale of roughly 5% of the company. Exchanges in New York, London, Hong Kong and Tokyo have all been vying for the international listing. Saudi Aramco is the world's largest integrated oil and gas company. The company has been valued at around $2 trillion by Saudi Crown Prince Mohammed bin Salman, but Reuters cite bankers and company insiders as saying its value is closer to $1.5 trillion. Saudi Aramco's IPO has been closely-anticipated in the last few years but has been delayed amid oil price volatility, valuation uncertainty, the location of the share listing and geopolitical events such the drone and missile attack in September. The IPO could be the world's largest, and if it achieves a valuation of $1.5 trillion Saudi Aramco would far exceed the market capitalization of market giants like Apple and Microsoft.