Saudi Arabia's oil company Aramco started trading publicly Wednesday with a record initial public offering. Shortly thereafter, it set the mark as the most-valuable listed company in the world.

Aramco started trading on the Saudi Tadawul stock exchange for the first time after a mammoth $25.6 billion initial public offering that set the record as the biggest ever in history.

At the opening of trading, its stock price gained 10% -- the daily regulatory cap limit -- hitting 35.2 Saudi riyals per share, or what is $9.39.

At that price, Aramco is the world's most valuable listed company at $1.88 trillion. That's more than the top five oil companies - Exxon Mobil, Total, Royal Dutch Shell, Chevron and BP - combined. 

To put it in perspective, that amount is nearly twice the U.S. federal deficit.