RIYADH, Saudi Arabia -- Saudi Arabia on Thursday said it transferred an additional eight percent stake from oil giant Aramco to firms owned by the kingdom's PIF sovereign wealth fund, according to state media.

Aramco is the jewel of the Saudi economy and the main source of revenue for de facto ruler Crown Prince Mohammed bin Salman's ambitious economic and social reform program known as Vision 2030.

In a statement carried by the official Saudi Press Agency, Prince Mohammed announced "the completion of the transfer of 8% of Saudi Aramco's total issued shares from the state's ownership" to companies fully owned by the Public Investment Fund (PIF).

The transfer was "a continuation of Saudi Arabia's long-term initiatives to boost and diversify the national economy and expand investment opportunities", SPA said.

The stake was worth "roughly $164 billion" at the company's current market capitalization, an Aramco media officer told AFP.

The move brings the state's ownership of Aramco shares to 82.19 percent, SPA reported, with a cumulative 16 percent transferred to the PIF and its subsidiaries.

Last year, four percent of Aramco's shares, worth tens of billions of dollars, were transferred to Sanabil Investments, a firm controlled by the PIF, one of the world's biggest sovereign wealth funds.

In 2022, another four percent of Aramco shares, estimated at the time to be worth $80 billion, were transferred directly to PIF.

"It's all about access to more investment capital. This boils down to bigger dividend payments, a stronger financial position, and more assets under management," said political economist Robert Mogielnicki.

"There is also a precedent to this transfer, which makes it easier to repeat," he told AFP, referring to the previous transfers.

Aramco and its assets were once kept under strict government control, completely off-limits to outside investment.

But under Prince Mohammed, the kingdom has slowly begun to cede some of that control.

The oil giant sold 1.7 percent of its shares on the Saudi stock market in December 2019, generating $29.4 billion in the world's biggest initial public offering.

The PIF has made high-profile investments in firms including Uber and Disney.

Its so-called giga-projects -- centerpieces of Prince Mohammed's reform agenda -- include Neom, a $500-billion futuristic megacity under construction in the Saudi desert.

The crown prince has said he wants the fund to have assets worth $1 trillion by the end of 2025.