Tension in the global diesel market is intensifying rapidly, with price gains significantly outpacing crude oil, as supply contraction becomes the primary force driving refined product prices higher.

In a report published on September 28, Citi pointed out that simultaneous contractions in diesel exports from the Middle East and Russia, combined with refinery output cuts, are expected to result in a global diesel deficit of approximately 1 million barrels per day this year. Whether supply can ease going forward depends critically on when crude oil and refined product transportation through the Strait of Hormuz resumes.

U.S. retail diesel prices have now risen to approximately $6.5 per gallon, compared with roughly $3.4 per gallon at the start of the year, with both diesel and heating oil prices approaching 55-year highs. The diesel crack spread has surged from about $25 per barrel at the beginning of the year to $89 per barrel as of September 24, while WTI rose only about $25 per barrel over the same period, indicating that this round of disruption is concentrated primarily on the refined products side.

Notably, the supply gap is being bridged through the inventory system. Global diesel inventories are expected to draw down by approximately 200 million to 250 million barrels this year, but visible primary inventories have declined by only about 50 million to 70 million barrels, meaning that a substantial portion of inventory consumption has already occurred at the end-user level.

Middle East and Russian Export Contraction, Refinery Cuts Further Amplify the Gap

Citi estimates that Middle East diesel exports could decline by approximately 500,000 to 1 million barrels per day, while Russia could see a reduction of about 300,000 to 600,000 barrels per day. Combined with refinery run cuts in other regions, global diesel supply is tightening further.

In August, unplanned refinery outages worldwide resulted in lost refined product output of approximately 3 million to 4 million barrels per day. Blocked exports and refinery output cuts have jointly intensified market tightness.

Currently, disclosed global diesel inventories stand at approximately 1 billion barrels, of which about 200 million barrels are held by European governments and about 400 million barrels belong to OECD commercial inventories. European government stockpiles therefore represent an important potential buffer, but the supply that can be released quickly remains limited.

If diplomatic channels fail, Citi believes European government inventories could be released at the latest after the U.S. midterm elections. The United States may also consider restricting diesel exports, though a full ban is unlikely; even if exports were restricted, a large volume of diesel stranded along the Gulf Coast could quickly strain local storage capacity.

Reopening of Hormuz Is the Key to a Diesel Market Turnaround

Citi's base case assumes that transportation flows through the Strait of Hormuz will return to normal in the fourth quarter of 2026, with a cumulative probability of approximately 70% across various reopening paths, including a 10-percentage-point scenario of a rapid agreement. Under this assumption, Brent crude is projected to fall back to $65 to $70 per barrel in 2027.

An alternative scenario is that tightness in the oil products market persists into 2027, corresponding to an indicative probability of about 30%. If the U.S. and Iran remain at an impasse, diesel supply pressure could persist for longer.

Citi's Brent price targets also incorporate the assumption of Hormuz reopening: a 0-to-3-month target of $75 per barrel, a 6-to-12-month target of $70 per barrel, and a 2027 forecast of $66 per barrel.

Therefore, the key going forward is not merely watching crude oil prices, but observing whether Hormuz transit volumes, Middle East and Russian diesel exports, and the diesel crack spread can improve in tandem. If shipping through the strait cannot be restored for an extended period, the current path toward supply normalization and falling oil prices will face reassessment; conversely, as transportation resumes and inventories are released, the diesel crack spread may be the first to decline.