ExxonMobil on Friday took the crown of the "world's most valuable company" back from Apple, as Apple's stock keep falling. Apple's stock has taken a serious knee-capping this week. As a result, Exxon on Friday became the world's most valuable company as Apple's stock fell $10.46, or 2.32%, to $440.04.

In midday trading, Exxon boasted a $417.59 billion market cap; Apple's was $412.36 billion.

Apple's stock has now dropped 37% since its September high of $702.10. In just the last two days, the stock is down 14.6%.

In August 2011, Apple first overtook ExxonMobil as the most valuable company in the world based on the value of its stock.