Saudi Arabia's vast oil resources, located close to the surface of its desert expanse, make it one of the world's least expensive places to produce crude. For every USD 10 rise in the price of a barrel of oil, Saudi Arabia stands to make an additional USD 40 billion a year, according to the Institute of International Finance. Shares in Aramco stood at USD 8.74 on Riyadh's Tadawul stock exchange before it opened Sunday. That's down from a high of USD 11.55 a share in the last year. However, that current price still gives Aramco a valuation of USD 1.9 trillion — making it the world's second most valuable company behind only Apple. The Saudi government still owns the vast majority of the firm's shares.