Apple has been usurped as the world's most valuable company after its shares continued to fall on Friday.
Exxon Mobil has regained the top place after Apple shares fell 2.4%, following a 12% drop on Thursday.
Apple, which posted disappointing iPhone sales figures on Wednesday, has seen its shares fall 37% since a record high last September.
Exxon became number one in 2005, traded places with Apple during 2011, and had been number two since early 2012.
At the close on Wall Street, Apple had a market value of $US413 billion, against $US418 billion for Exxon.
Apple said on Wednesday that it sold more iPhones (47.8 million) and iPads (22.9 million) in the final three months of last year than in any previous quarter, but the BBC reports investors and analysts had expected yet more.
About $US50 billion was wiped off Apple's value on Thursday.
Apple's shares, which were worth $US3.19 in 1997 when it faced the possibility of bankruptcy, reached a record $US702.1 on 19 September, 2012.