Saudi Crown Prince Mohammed Bin Salman attends the launch of the ABB FIA Formula E Championship in Diriyah district in Riyadh. File/ AFP

Saudis took to Twitter to celebrate Aramco's valuation hitting $2 trillion on Thursday, with one posting praising de-facto leader Crown Prince Mohammed Bin Salman as a fortune teller.

"Few people have the ability to predict the future," journalist Mosaed Al Zayani posted on Twitter, a platform favoured for pro-government commentary in Saudi Arabia.

Officials at the ceremony launching the debut of Saudi Aramco's initial public offering (IPO) in Riyadh.  File/AFP

"He (the Saudi crown prince) said years ago Aramco's valuation was $2 trillion and today it is the first company in the world to exceed this number," Zayani added.

Saudis shared photos and videos of the crown prince, who made the IPO the centrepiece of his plan to diversify the kingdom's economy away from oil and open up its society.

Although the world's most profitable company fell short of the royal target during its long-awaited initial public offering (IPO) process, it finally crossed the line on Thursday as shares racked up a second day of gains.

Local media headlines included "A dream come true" and "Aramco at the top of the world" after the stock's debut.

Amid patriotic fervour in the lead-up to the IPO, Saudis had clamoured to own part of the kingdom's "crown jewel," with more than 5 million retail subscribers.

A man looks at an advert for Aramco on Twitter in Riyadh. File/ AFP

Saudi energy minister Prince Abdulaziz Bin Salman had predicted Aramco's valuation would rise after initial trading, telling reporters last week that investors who stayed away would be "chewing their thumbs."

"The $2 trillion valuation is not a dream," Saudi economist Fadl Alboainain said, adding: "The government accepted a lower valuation to fast-track the IPO and placed a winning bet on market valuation for the company."

Some market professionals have called the IPO as the biggest migration of private sector money to government pockets, but the government plans to locally invest most of the 96 billion riyals raised, its finance minister said this week.

Reuters