UBS Survey: Over 6 million barrels per day passed through the Strait of Hormuz in the past week

The tension between the US and Iran remains ongoing, but the market's focus is gradually shifting from military risks to economic sanctions and their impact on the global crude oil supply landscape.

According to Xinhua News Agency, US Treasury Secretary Bensent stated on the 20th that the Trump administration will intensify economic pressure on Iran and has threatened to implement “unprecedented economic isolation” measures against the country. He claimed that the Trump administration’s plan to severely damage Iran’s economy may allow the US to avoid launching large-scale military operations against Iran. With the possibility of increased sanctions, their impact on Iran's crude oil exports is becoming a new variable drawing market attention.

Meanwhile, visible tanker traffic through the Strait of Hormuz remains noticeably below pre-conflict levels, but "covert" shipments are partially filling the gap. According to UBS research data, over the past week, total oil flows in the Strait of Hormuz remained slightly above 6 million barrels per day, with covert shipments rising to around 5 to 6 million barrels per day, indicating that the actual impact on crude oil transits may be less severe than what surface shipping data suggests.

What deserves more attention is that while Iranian supply remains constrained, crude oil loadings from other Gulf oil-producing nations are rapidly recovering. The current market is not simply facing a sharp total supply drop, but rather a restructuring of the regional oil supply pattern.

Visible tanker flow remains low

According to UBS Evidence Lab data, the average number of oil and gas vessels transiting the Strait of Hormuz over the past two days was 4.0, higher than the August average of 3.7, but significantly below July’s average of 6.4. Based on deadweight tonnage estimates, the Gulf’s export flows over the past two days were about 1.5 million barrels of oil equivalent per day, not only lower than August’s average of 1.9 million barrels per day, but also well below July’s average of 3.6 million barrels per day.

However, storage and loading data indicate that over the past week, “covert” shipments have climbed to 5 to 6 million barrels per day, partially offsetting the decline in visible transportation and keeping the Strait of Hormuz’s total transits slightly above 6 million barrels per day. Ship traffic through the Bab el-Mandeb Strait is also below normal levels, but import and export flows toward the Red Sea have recently rebounded.

Meanwhile, crude oil loadings from other Gulf oil-producing nations are clearly recovering. Over the past two days, the average crude loading volume of non-Iranian producers in the Gulf rose to 10.2 million barrels per day, far higher than the previous two days’ 3.6 million barrels per day, and above July’s average of 4.5 million barrels per day; since August, the 7-day average has exceeded 6 million barrels per day, reaching a new high since the conflict began.

In stark contrast, Iranian crude loadings remain at extremely low levels. During the same period, Iran recorded zero loadings, with an August average of only around 200,000 barrels per day, below July's 900,000 barrels per day, and even further below the normal level of around 1.7 to 1.8 million barrels per day.

This indicates that a clear structural divergence is emerging in Gulf supply: Iranian exports remain constrained, while other oil-producing nations are offsetting the supply gap to a certain extent by increasing their loadings.

Energy supply still faces disruption

At the same time, previous rounds of disruptions to regional energy infrastructure remain an important backdrop for the market’s assessment of supply risk. Some Gulf energy facilities and refining capacity were affected by attacks; although part of the capacity has gradually resumed, related disruptions have kept Gulf crude oil and refined product shipments below normal levels.

Therefore, the market's main focus going forward has shifted from individual incidents to recovery in supply capacity: on one hand, whether the new round of US sanctions can further curtail Iran’s crude exports; on the other, whether other Gulf oil producers can continue to boost supply and fill the gap left by Iran.

If Iran's exports shrink further and substitute production proves insufficient, upward pressure on crude supply in the market may persist, and changes in shipments through the Strait of Hormuz will remain an important indicator impacting oil prices.