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.

ExxonMobil said it expects to take an up to $900 million hit to its upstream earnings in the fourth quarter versus the previous three months amid falling oil prices.

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,

The change in gas prices, however, may boost earnings by as much as $400 million for the quarter, the company said..

Exxon Mobil signaled on Tuesday that sharply lower oil refining profits and weakness across all its businesses would reduce its fourth-quarter earnings by about $1.75 billion from the prior quarter. The oil major also said in an SEC filing that upstream asset sales would benefit results by about $400 million,