Oil prices fell for a second day on 18 June 2026 after the United States and Iran signed a peace agreement, according to Reuters, removing the geopolitical risk premium that traders had priced into crude markets. The selloff extended a move that began on 14–15 June, when the two countries announced a halt to hostilities and committed to keeping the Strait of Hormuz open to maritime traffic.

The Strait of Hormuz is the world's most critical oil chokepoint. Roughly one-fifth of global petroleum supply transits through it, including the bulk of crude exports from Saudi Arabia, Iraq, the UAE, Kuwait, and Iran. When traders fear the Strait might close, they push prices higher across the entire forward curve—a preemptive bet on supply disruption. When that threat dissolves, the unwind is mechanical: prices fall as those risk bets reverse.

Iran's government had already signalled restraint before the deal closed. In March 2026, Iran's Ministry of Foreign Affairs issued a statement affirming that the Strait remained open and traffic uninterrupted. This came alongside intense diplomatic pressure: Iran's UN Ambassador had separately written to the Secretary-General objecting to what Tehran described as CENTCOM's unlawful measures in the Strait. Both sides signalled restraint publicly while legal and military posturing advanced in parallel.

Multilateral engagement intensified as well. A 35-country ministerial meeting chaired by the United Kingdom convened to address Strait security, per the Saudi Press Agency. That kind of emergency coalition-building reflects how deeply exposed the global energy supply chain is to disruption there. Governments typically don't convene ministerial meetings over hypothetical scenarios.

The price action across both sessions fits the pattern of a classic risk-premium compression trade. When a tail risk—closure of Hormuz, interdiction of tanker traffic—is priced into the front month but then visibly de-escalates, leveraged longs unwind quickly. There is no inventory shock or physical supply disruption to absorb; the move is purely a repricing of probability-weighted outcomes. The speed reflects how liquid crude futures are and how efficiently they incorporate headline diplomatic shifts.

Where prices settle now depends on structural variables independent of geopolitics. OPEC+ production policy, demand in China and India, and non-OPEC supply growth from the US, Guyana, and Brazil all matter. With the Hormuz premium largely drained, the market returns to debating those fundamentals. Iran's export capacity—constrained by sanctions for years—becomes material again if the peace deal holds and sanctions relief follows. Incremental Iranian barrels would add to what is already an adequate global supply picture.

But peace agreements between the US and Iran have been fragile in the past. The specific terms of the 18 June deal—what each side conceded, whether Congress supports sanctions relief, how Iran's domestic politics receives it—will determine whether de-escalation proves durable or a temporary equilibrium. Futures markets can reprice that risk back in as quickly as they priced it out.

For oil traders, the signal is straightforward: geopolitical risk has thinned considerably. For longer-term investors—sovereign wealth funds and national oil companies with medium-term exposure—the more consequential question is whether this diplomatic settlement allows Iranian production to recover toward its pre-sanctions level of roughly 3.5–4 million barrels per day. That volume would shape the supply balance in ways that two days of futures volatility does not.