With the stock market listing of its national oil company stalled, Saudi Arabia is scrambling to boost the coffers of the sovereign wealth fund spearheading a risky plan to diversify its economy.

The Public Investment Fund (PIF) had sought to raise billions of dollars through the initial public offering (IPO) of Saudi Aramco - dubbed as potentially the world's biggest stock sale - to finance the kingdom's transformation from a petro-state to a tech-focused economy.

But with the flotation indefinitely postponed, the PIF is taking radical steps to boost its treasure chest with much-needed cash to finance a slew of non-oil investments - from risky hi-tech startups to a new mega city.

Pivoting the desert kingdom's economy away from oil, akin to what observers describe as turning around a large, lumbering ship, is a key priority for Crown Prince Mohammed bin Salman.

When the Aramco IPO was proposed in 2016, Saudi officials had expected it would raise up to $100 billion to fund his reform agenda, based on a $2 trillion valuation of the state-owned giant that many experts said was unrealistic.

With IPO efforts floundering, the once-torpid PIF, which aims to raise its assets from roughly $230 billion to more than $2 trillion by 2030, is aggressively pushing a host of big-ticket investments - from Uber to the planned $500 billion NEOM megacity on the Red Sea coast.

The fund has also invested in British tycoon Richard Branson's space tourism company Virgin Galactic and pledged tens of billions of dollars to funds run by SoftBank and Blackstone. Some analysts have voiced concern over the PIF's "spend to grow" strategy as it pursues what are seen as flashy deals rather than long-term investments that deliver secure returns and generate jobs as unemployment soars.