As the biggest stock in the world, Exxon Mobil (XOM) has a huge impact on the performance of widely followed cap-weighted stock market indices like the S&P 500. After today's $3.23 gain (its first gain of more than $3 since March 2009), XOM is up just under 50% since the S&P 500 made its 2010 correction low last July. As shown below, the stock has basically gone straight up in recent months.
As noted above, Exxon Mobil is currently the biggest company in the world. Its current market cap is $423 billion. We have written a few posts before on Apple's (AAPL) attempt to surpass XOM as the biggest company in the world, but after Exxon's recent surge, the competition can be put on hold for now.
As shown below, Apple got pretty close to XOM in mid-2010. In late June, there was just a $35 billion difference in market cap between the two. While both stocks have been going up since then, XOM has been going up more. After today's big gain for Exxon, the difference in market cap has moved above $100 billion for the first time since April 20th, 2010.