Oil-Fueled Selloff Sends Nikkei 225 Tumbling 1.9%; Banks and SUMCO Stand Out as Safe Havens

Japan’s Nikkei shed 1.92% after Brent crude topped $78 on US-Iran tensions, with broad sector sell-offs wiping out last week's tech rally. Key support levels breached.

Brent crude’s surge above $78 a barrel on Monday, sparked by escalating US?Iran hostilities and a claim by Tehran that the Strait of Hormuz had been closed, ripped through Japanese equities almost as soon as the opening bell rang. The Nikkei 225, which had started the session at 68,410.63 and briefly touched 69,078.21 in early trade, reversed sharply as oil?price anxiety swept across Tokyo. By the closing bell the index had shed 1.92% to settle at 67,242.73, wiping out the bulk of the prior week’s tech?driven rally.

The sell?off was unusually broad and deep. More than two?thirds of the 33 T?ky? bourse sectors finished in the red, and trading volume swelled well above the 30?day average as institutional investors rushed to lock in profits. The panic spread beyond Japan: South Korea’s Kospi collapsed by more than 8% at one point, reinforcing the negative momentum across Asia. Australia’s S&P/ASX 200 lost 0.35% and China’s CSI 300 fell 0.64%, while Hong Kong’s Hang Seng managed a rare 0.91% gain.

Energy?sensitive industrial and technology stocks bore the brunt of the selling. Yaskawa Electric plummeted 14.2%, hammered by rising input costs and fears over supply?chain disruption. Semiconductor names followed suit: Advantest gave up 5.47% and Taiyo Yuden slid 4.8%, as investors dumped the “AI premium” stocks that had powered the index higher in previous weeks. Heavyweight Fast Retailing added to the pressure, dropping 2.1%.

Yet the rout was far from universal. SUMCO Corp surged 7.9%, lifted by sector?specific demand, while the financial sector proved a steadying force. Mitsubishi UFJ Financial gained 2.4% and Sumitomo Mitsui Financial rose 2.1%, buoyed by lingering expectations of further interest?rate hikes in Japan. SoftBank Group also bucked the trend, advancing 2.0% on the strength of its diversified global portfolio.

From a technical perspective, the Nikkei’s slide punched through several critical support levels in a single session. The psychologically important 68,000 line gave way, and the index is now testing the zone around 67,000. The 14?day relative strength index plunged from overbought territory, signaling a rapid shift in momentum. The 70,000 mark, which had been the target of the earlier rally, now appears to have solidified as a robust resistance level. Traders are watching 66,800 as a potential floor; a break below that could accelerate losses toward the 65,000–65,800 range. Still, the index remains nearly 20% above its 200?day moving average (56,066.43) and the 50?day moving average at 66,201.69 sits only 1.57% below the close, suggesting the medium?term uptrend is bruised but not broken.

The catalyst for Monday’s turmoil lies squarely in the Middle East. Brent crude climbed 3.3% to $78.50 a barrel, while US crude rose 3.4% to $73.83, after Iran said it had closed the Strait of Hormuz—a claim immediately disputed by President Trump, who insisted the waterway remained open to commercial traffic. For Japan, a major energy importer, the spike directly threatens corporate margins and import costs. The yen edged up to 161.70 against the dollar, providing a modest headwind for exporters but potentially easing the import?cost burden if the currency stabilizes.

Adding to the pressure, the dollar and US bond yields strengthened after markets repriced the probability of another Federal Reserve rate hike. Fed Chair Kevin Warsh is scheduled to testify before Congress on Tuesday, the same day June US inflation data will be released. The twin headwinds of a stronger dollar and higher yields weigh particularly heavily on export?oriented Japanese names.

Attention now turns to the US earnings season, which kicks off this week, and to whether the geopolitical risk premium in oil holds. The Nikkei’s annualised 30?day volatility has surged to 35.72%, underscoring the frayed nerves. On a 12?month basis the index is still up more than 70%, but the swift retreat from the 72,831.73 peak hit on June 22 highlights how quickly the mood can sour when energy prices and geopolitics collide. The coming sessions will be dictated by headlines from the Gulf and the tone of Fed communications—a volatile cocktail that promises to keep Tokyo traders on edge.