Saudi Arabia is preparing to formally launch a secondary offering of shares in oil giant Aramco as soon as Sunday, a deal that could raise more than $10bn and rank among the largest of its kind in recent years.The government plans to run a book-building process to take orders until next Thursday, people familiar with the matter said, asking not to be identified as the information is private. The deal has attracted informal interest from investors across the Mideast and Europe totalling over $10bn, they said.The offering will likely be priced at a further discount of as much as 10% to the trading price, though that could narrow based on investor demand, some of the people said. That’s in line with secondary sales in Saudi Telecom Co and Tadawul Group Holding, which operates the kingdom’s stock exchange.No final decisions have been made on the offering period. Terms of the deal, including its size, could still change, the people said. Aramco didn’t immediately respond to requests to comment.The offering is set to come days after Aramco’s stock dropped to the lowest level in over a year. The deal opening will coincide with an Opec+ gathering on Sunday to discuss oil output policy, with most market-watchers expecting the group to maintain supply curbs. That would keep Saudi Arabia’s production near the lowest level in about three years.The kingdom is lining up a slate of banks including Citigroup Inc, Goldman Sachs Group Inc and HSBC Holdings Plc for the deal, Bloomberg News has previously reported. Local firms including Saudi National Bank are likely to be involved, people familiar with the matter said, while Moelis & Co has been acting as a financial adviser to help pick underwriters.The follow-on offer would come almost five years after Saudi Arabia raised about $30bn in Aramco’s IPO, which was the world’s largest ever stock sale.Some of the Wall Street banks likely to be involved in the secondary offering also worked on that listing, when they were paid just over $100mn. In comparison, banks including Goldman and JPMorgan split about $60mn from helping Peloton Interactive Inc raise $1.2bn in 2019.Low fees are common in the Middle East. For bankers, the share sale is a trade-off between working for less and the prospect of winning more business in the largest Gulf economy that’s in the middle of a multitrillion-dollar overhaul.Proceeds from the share sale will help fund big initiatives tied to that economic transformation. Crown Prince Mohammed bin Salman’s plans include a push into artificial intelligence, sports, tourism as well as projects such as the $1.5tn development of Neom.The deal comes at a crucial time for the kingdom, which holds an 82% stake in the $1.9tn firm. Crude oil prices are below the levels the government needs to balance its budget and Saudi Arabia has lagged behind its target of attracting more than $100bn a year in foreign direct investment.The government needs oil near $100 a barrel to pay for its spending plans, according to the International Monetary Fund. But global oil benchmark Brent, currently at about $85, is forecast to be near $79 in 2025 and $75 the following year, according to estimates compiled by Bloomberg.Aramco’s oil production is also restricted by Opec+ policy as the group’s leading member Saudi Arabia tries to revive the market and boost prices. The company already has large unused output capacity, and earlier this year was ordered by the government to halt a further expansion of its capability.Against that backdrop, and amid questions about climate change and the future of fossil fuels, the offer will test global investors’ appetite. Aramco’s IPO had relied mostly on local investors, who’d faced pressure from the government to back the deal after most foreign money managers balked at valuations.While the company’s massive dividend payouts may now be a draw, its shares are expensive with price-to-earnings ratios almost 50% higher than Exxon Mobil Corp and double Shell Plc’s.Any deal will also coincide with a resurgence in the Saudi market for new share sales — investors have ploughed in a combined $176bn in orders for four deals in recent weeks. That’s higher than the orders for Aramco’s 2019 IPO and is weighing on the kingdom’s stock market.The Tadawul All Share Index is trailing its emerging-market peers for the first time since the pandemic and has fallen almost 8% from its March peak — partly because of investors who’re holding on to cash to invest in the offerings.