Jan 7 (Reuters) - U.S. oil major Exxon Mobil ( XOM ) said on Wednesday that lower crude oil prices could cut its fourth-quarter upstream earnings by about $800 million to $1.2 billion.

Oil prices declined 9.2% during the three months ended December 31, as concerns ‌about oversupply and tariffs outweighed geopolitical risks.

Brent crude futures shed about 19% in 2025, the ​most substantial annual percentage decline since 2020 and their third straight ‍year of losses, the longest such streak on record. ⁠U.S. West Texas ⁠Intermediate crude logged an annual decline of almost 20%.

The company said in a regulatory filing ‌that changes in gas prices could ​affect its quarterly upstream earnings from a negative $300 million to as much as a positive $100 million.

Exxon's snapshot is closely ⁠watched for clues on how the ‍broader ​oil sector will fare when companies begin releasing quarterly results in a few weeks.

Analysts expect Exxon to report adjusted earnings of $1.66 per ‍share for the fourth quarter, according to data compiled by LSEG.

"However, we think many brokers, including us, have yet to mark to market, which could lead to lower earnings estimates given the lower oil and gas prices compared with expectations at the beginning of 4Q25," ​Scotiabank ‍analysts said in a note.

Exxon also said restructuring charges could negatively impact overall earnings by about $200 million. Late last year, the ​company had flagged that its corporate plan focused on cutting costs and boosting profit even through periods of oil price volatility.

Still, it signaled that stronger margins in the refining business could boost earnings by $300 million to $700 million in the fourth quarter.

Exxon is set to release results for the final quarter of ​the year on January 30, the filing showed.

The energy major had posted $5.7 billion in upstream earnings for the third quarter. Its total profit stood at $7.5 billion during the period.

(Reporting ‍by Pooja Menon in Bengaluru; Editing by Shilpi Majumdar and Anil D'Silva)