The Iran Deal Just Triggered the Biggest Single-Day Asian Market Surge in Years. Here Is What Happened.
When US President Donald Trump posted on Truth Social on June 15 that the deal with Iran was complete and that the Strait of Hormuz would open, global markets responded immediately and dramatically. Asian markets, which had borne the heaviest direct exposure to the four-month Strait closure, led the rally.
Japan's Nikkei 225 soared 5.5% in a single morning session, its strongest single-day gain in months. South Korea's KOSPI jumped as much as 5.7%. Taiwan's TAIEX climbed 2.7%. Australia's ASX 200 rose 1.5%. The Hang Seng in Hong Kong gained around 1% before giving back most of the advance later in the session. US futures also surged, with contracts tied to the Nasdaq rising around 1.8% and the S&P 500 futures adding roughly 1%.
The scale of the Asian rally reflects how directly the region had been hurt. China, India, Japan, and South Korea together account for 75% of the oil and 59% of the LNG that normally flows through the Strait. When Iran closed the waterway on February 28, those four economies faced the most immediate pressure from higher energy import costs, tighter fuel supplies, and supply chain disruptions that cascaded through manufacturing sectors across the region.
Norihiro Yamaguchi, lead economist for Japan at Oxford Economics, described the timing as additionally supportive because major central bank policy meetings had just concluded, reducing one key source of uncertainty. He added that the renewed strength in US semiconductor stocks provided an extra boost for Asian technology shares given the region's heavy exposure to that sector.
Oil prices fell sharply on the deal news, with Brent crude down almost 5% on June 15 and ultimately falling around 20% from its 2026 peak of $126 per barrel. That price decline directly reduces input costs across energy-intensive Asian manufacturing, which economists had flagged as one of the primary channels through which the Strait closure was damaging corporate earnings across the region.
The rally was real but the implementation has been complicated. Iran temporarily closed the Strait again on June 20 citing Israeli actions in Lebanon. On June 27, the US Navy's Joint Maritime Information Center announced a widened route through the Strait near Oman, allowing increased naval traffic in both directions. Normalization of full energy flows is expected to take months, not days.
