Exxon Mobil (NYSE:XOM) -1.4% in Wednesday's trading after saying its Q4 earnings were hurt by lower crude prices and narrower refining margins, in a sign that the quarter may have been a tough one for the big oil companies.

Exxon Mobil said on Tuesday changes in oil prices would ease its fourth-quarter upstream earnings by $500 million to $900 million.

Exxon Mobil profits will likely miss fourth-quarter-earnings estimates by close to 20%, one analyst argued as he trimmed his numbers. While Exxon Mobil expects changes in gas prices to improve earnings by up to $400 million,

Exxon's earnings snapshot signaled profits "well below consensus," said Biraj Borkhataria, an oil analyst with RBC Capital Markets, in a note to investors. The forecast showed "significant headwinds" in refining, he added.