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If poor earnings reset Apple Inc.’s (NASDAQ: AAPL) shares back to where they traded in September, the market value of Exxon Mobil Corp. (NYSE: XOM) may well top that of the consumer electronics company. As a matter of fact, a 10% sell-off in Apple’s stock due to the unexpectedly low sales of iPhones and a poor forecast would make the race close.

Apple’s market capitalization stood at $550 billion before what is expected to be a plunge. A drop of 10% would push shares to $495 billion, just below the critical $500 billion mark. Apple’s value would fall from $495 billion to $445 billion under those circumstances. And Apple’s shares lost substantially more than that in both dollars and on a percentage basis when the company began to disappoint investors with lackluster products just a year ago. The stock quickly sold off from more than $700 a share in late 2012 to $440 in January 2013.

Exxon’s stock price has been much more stable over the past year. It has risen steadily from August’s level of $85 to $95 more recently. The stock topped $100 late last year. At that point in December, Exxon’s market cap was $441 billion. It would only have to recapture that level to match the point to which Apple will fall — if Apple’s recent share price history is any indication.

Exxon has an important advantage over Apple. Its earnings are expected to rise in 2014, a forecast that could be cemented when it releases year-end earnings. At this point, Wall Street expects full-year 2014 earnings to reach $7.84 per share, up from $7.40 this year.

Exxon has one other advantage — the seal of approval from Warren Buffet. As MarketWatch reported recently:

Shares of Exxon Mobil Corp. have outpaced rivals in recent months, basking in a “Warren Buffett effect” and also thanks to soaring natural-gas prices.

For anyone considering it, however, Exxon XOM -0.07% is still more expensive than many of its peers, and the market is growing nervous about falling oil-futures prices. Most analysts still have a “hold” rating on the stock.

Exxon has gained 13% in the past three months, compared with gains of 0.8% for the NYSE Arca Oil index, which encompasses Chevron Corp., ConocoPhillips, BP PLC and other energy heavy-hitters.

Buffett’s Berkshire Hathaway Inc. took a major stake in Exxon in November, buying a little over 40 million shares worth nearly $4 billion.

Exxon is also the No. 1 natural-gas producer in the nation thanks to the XTO Energy, announced in 2009 and completed a year later. Natural-gas prices rallied Tuesday as a winter storm hit the Northeast and the Midwest, and some analysts calling for a “Polar Vortex II.”

Based on most current evidence about the two companies, Exxon’s move into first place is likely only a matter of time.