Brent Crude’s 19% Monthly Plunge: Inside the Ceasefire That Shattered Oil’s War Premium

Brent crude is spiraling toward its worst monthly performance since the pandemic-driven collapse of 2020, shedding nearly a fifth of its value in May 2026. The proximate cause is a sudden unwinding of the geopolitical risk premium that had been built into every barrel since the U.S.-Iran conflict effectively closed the Strait of Hormuz nearly ten weeks ago. Reports that Washington and Tehran have tentatively agreed to extend a ceasefire by 60 days—and are discussing a framework to reopen the strait to unrestricted commercial shipping within weeks—have convinced oil markets that the worst-case supply scenario is off the table .

But the story beneath the price chart is more complicated. The same bottlenecks that made the crisis so acute—stratospheric war-risk insurance, a monumental queue of idle vessels, and a still-active mine threat—will not vanish with a diplomatic handshake. The selloff reflects a “peace premium” being priced out, yet the physical oil market remains deeply distorted, and a frictionless return to normal flows is unlikely.

The Ceasefire Catalyst: Why Markets Rushed for the Exit

The primary driver of the selloff is a rapid reassessment of geopolitical risk. After weeks of conflicting signals, multiple reports emerged in the final days of May that U.S. and Iranian negotiators had reached a 60-day memorandum of understanding to extend the fragile ceasefire and open negotiations on broader issues, including Iran’s nuclear program . Crucially, the draft framework reportedly included provisions for unrestricted shipping through the Strait of Hormuz and a commitment by Iran to remove all mines from the waterway within 30 days .

This was the signal traders had been waiting for. The strait normally carries about 20% of global oil and LNG supplies, and its de facto closure had been the single largest supply disruption in decades . The mere possibility that those barrels could soon flow again was enough to trigger a cascading selloff. Brent plunged 10.5% in the last week of May alone, the steepest weekly drop since the week ending April 6 . From a start-of-month level around $113 per barrel, Brent had collapsed to approximately $91.87 by May 28–29, locking in a monthly decline of nearly 19% . West Texas Intermediate mirrored the move, settling around $88.68 per barrel on May 28 .

President Donald Trump had not yet approved the proposed terms as of the latest reports, and Vice President JD Vance cautioned that it remains uncertain when or whether a final agreement can be reached . Yet markets have already begun pricing in a high probability of success, driven by tangible small-scale progress: Iran’s navy reported that 32 vessels had transited the strait after receiving clearance from the IRGC Navy on May 25, and additional ships were allowed through in the following days .

The Scale of Hormuz Paralysis: A 95% Traffic Collapse

To understand why a mere peace rumor could erase tens of dollars from a barrel of oil, one must grasp the staggering scope of the Hormuz disruption. Before the conflict, the strait saw 100 to 140 vessel transits daily . By late May, traffic had cratered to roughly 10 ships per day—a decline of about 95%—with some days seeing only a single crude tanker pass through .

The physical backlog is extraordinary. An estimated 1,800 to 2,000 vessels are anchored outside the strait, waiting for safe passage . This is not merely a queue of oil tankers; it includes container ships, LNG carriers, and bulk freight vessels that service the entire Gulf region. Untangling this logjam will be a monumental logistical challenge even after the strait is declared safe.

Compounding the paralysis is an insurance market that has effectively priced transit out of reach for many commercial operators. War-risk premiums for vessels navigating the strait have surged to approximately 20% of the vessel or cargo value . For a single VLCC carrying $100 million in crude, that translates to a $20 million surcharge—an expense that renders many voyages economically prohibitive even when permission to transit is technically granted.

The United Kingdom Maritime Trade Operations (UKMTO) continues to list the maritime risk level as CRITICAL with active mine warnings, and this classification will need to be downgraded before most underwriters will consider normalizing premiums . That process typically takes weeks to months, not days.

By the Numbers: May 2026 Price Snapshot

Metric	Value	Context
Brent crude monthly decline	~19%	Worst month since COVID-19 crash of 2020
Brent crude (May 28–29)	~$91.87/bbl	Down from ~$113 at start of month
WTI crude (May 28)	~$88.68/bbl	Down over 5% in single session
Brent weekly decline (final week)	10.5%	Steepest since week ending April 6
U.S. gasoline (year-on-year)	~$4.51/gal	Up over 50%, reflecting accumulated war premium
Pre-war Strait transits/day	100–140	Normal baseline before conflict
Late-May transits/day	~10	~95% decline

Where Analysts See Prices Heading Next

If the ceasefire framework evolves into a comprehensive, signed agreement, the consensus among analysts is that there is significant further downside. Projections call for Brent to reach $82–$85 per barrel by the third quarter of 2026, reflecting the full removal of the war risk premium and the expected gradual resumption of tanker flows .

However, the U.S. Energy Information Administration’s May Short-Term Energy Outlook injects important caution into this narrative. The EIA notes that war-related production outages and the resulting large draws on global oil inventories—particularly acute in May and June—will limit how quickly downward pressure can build even after flows through the strait start to rise . Physical supply cannot snap back instantly when infrastructure has been damaged and upstream production disrupted.

OPEC+ dynamics add another layer of uncertainty. The UAE announced its departure from OPEC effective May 1, 2026, and OPEC+ output reportedly fell by around 1.74 million barrels per day in April alone . While the bloc’s production cuts are providing some price support, non-OPEC supply growth and OPEC’s own downward revisions to global demand forecasts—cut to 1.17 million barrels per day from 1.38 million—are exerting countervailing pressure .

The Three Bottlenecks That Will Delay Recovery

Even with a signed deal, the oil market faces three sequential bottlenecks that will prevent a rapid return to pre-war shipping volumes:

1. The insurance bottleneck. War-risk premiums hovering near 20% of vessel value are unsustainable for mass commercial transit. Underwriters will require a formal downgrade of the UKMTO risk classification, verified mine clearance, and a sustained period without hostile incidents before they reprice the strait to standard-risk levels. Industry estimates suggest this could take anywhere from several weeks to a few months .

2. The shipping backlog. A queue of 1,800–2,000 vessels cannot be cleared overnight. Port infrastructure on both sides of the strait has limited throughput capacity, and priority conflicts—between crude tankers, product carriers, LNG vessels, and container ships—will create scheduling nightmares. Some fraction of this backlog represents vessels that will no longer need to transit once the urgency passes, but the sheer number guarantees congestion for weeks or months .

3. Persistent physical risk. The UKMTO’s CRITICAL classification reflects a real and present danger: mines remain in the waterway, unexploded ordnance poses a threat to hulls, and the ceasefire itself remains fragile. The tentative agreement requires Iran to clear mines within 30 days of final approval, but even after clearance, residual risk will keep some operators and insurers cautious .

What This Means for Consumers and Markets

The divergence between crude oil’s rapid retreat and persistently high consumer fuel prices tells a story of asymmetric transmission. U.S. gasoline prices remain elevated at roughly $4.51 per gallon—more than 50% above year-ago levels—because the war premium built up over months is slow to exit the refined product supply chain . Refiners bought expensive crude during the crisis, and those costs are still working their way through the system.

For global markets, the episode underscores a structural vulnerability that extends beyond this single conflict. The Strait of Hormuz remains the world’s most critical oil chokepoint, and the 2026 crisis has demonstrated that a single geopolitical shock can vaporize roughly 20% of global supply in a matter of weeks . The speed of the price decline now reflects how quickly that risk can be repriced when peace appears plausible—but the speed of the physical recovery will be measured in months, not trading sessions.

The market’s May collapse is essentially a bet that diplomacy will succeed where force could not. But the vessels still waiting at anchor, the insurers still demanding war-risk premiums, and the mines still floating in the strait all argue that the all-clear has not yet sounded.