Chevron Corp. said its production fell as much as 6% in the first quarter due in part to the Iran war, echoing a similar disclosure from arch rival Exxon Mobil Corp. earlier this week.

Chevron’s production was between 3.8 million and 3.9 million net oil-equivalent barrels per day, the company said Thursday in a filing. That compares with 4.05 million barrels during the fourth quarter of 2025.

The company attributed the decline to reduced output in the Persian Gulf region and Israel, as well as downtime at operations in Kazakhstan.

Chevron also outlined the effect on its earnings from the war-related spike in oil and natural gas prices. It expects a negative impact of as much as $3.7 billion due partly to how derivatives are marked to market.

The impact of physical energy deliveries at higher prices aren’t recorded until deliveries are completed, a phenomenon that Chevron and Exxon both refer to as “timing effects.” The negative impact of timing effects should unwind over subsequent quarters, Chevron said.

Higher commodity prices will lift earnings from Chevron’s upstream segment by as much as $2.2 billion compared with the fourth quarter.