The first independent audit of Saudi Aramco’s Initial Public Offering (IPO) oil reserves has confirmed the state oil company’s own figures, sources familiar with the situation said, ahead of its planned share market listing in 2018, Reuters reported.

According to Aramco’s own estimates, the Saudi oil giant has 261.1b barrels of crude oil and condensate reserves. However, according to the BP Statistical Review of World Energy, the country’s total proved reserves were 266.6b barrels at the end of 2015, Oil Price informed.

Two more sources stated that the audit has found that the reserves were “definitely not below” Aramco’s own estimates.

The listing, expected to be the world’s biggest IPO, is a centerpiece of a Saudi Arabian government plan to transform the country by enticing investment and diversifying the economy away from oil. The company ad asked two U.S. oil reserve auditing specialists to review its deposits.

In view of 2018’s share listing, Saudi Aramco is required to provide independent audit of its reserves.

Significantly higher or lower reserves would greatly change the evaluation of the company, which Saudi officials say is worth around $2t.