Jakarta. Jakarta Composite Index (JCI) plunged sharply at Wednesday’s midday close as escalating geopolitical tensions in the Middle East rattled global markets and triggered broad selling across Asian equities.

The benchmark index dropped 343 points, or 4.32%, to 7,596 at the end of the first trading session. During the morning session, the index moved in a deep red zone, fluctuating between 7,584 and 7,897.

Trading activity remained heavy. Data from the Indonesia Stock Exchange (IDX) showed 35.07 billion shares changing hands in 2.12 million transactions, generating a total turnover of Rp 18.1 trillion ($1.07 billion).

Market breadth reflected intense selling pressure, with 713 stocks declining, far outnumbering 63 gainers, while 37 shares remained unchanged. Blue-chip stocks were also heavily hit, with the LQ45 index slumping 4.19%.

IDX Director of Trading and Member Regulation Irvan Susandy said the domestic sell-off mirrored sharp declines across regional markets.

“The movement of the JCI is in line with other regional indices that have also dropped sharply, including the Kospi, SET, Kosdaq, Nikkei, Taiwan TAEIX, and ASX,” Irvan said on Wednesday.

He noted that South Korea’s market briefly triggered a trading halt after falling more than 8%, underscoring the scale of the sell-off.

According to Irvan, the pressure stems from escalating geopolitical tensions in the Middle East after Iran closed the Strait of Hormuz, raising fears of a potential global energy crisis.

“This development is already reflected in the increase in global oil prices,” he added.

Brokerage Kiwoom Sekuritas Indonesia said the sell-off was driven by multiple factors, including the escalation of the US–Iran conflict, a broad correction in Asian bourses, pressure on big-cap and conglomerate stocks, as well as domestic regulatory updates on shareholder transparency for stakes above 1% and discussions about raising the minimum free float requirement.

Separately, Phintraco Sekuritas said concerns that the US and Israel’s war against Iran may last longer than previously expected had amplified negative sentiment in Indonesia’s market.

“Concerns that the US/Israel war against Iran could last longer than previously expected have become a negative sentiment pushing the JCI lower,” the brokerage wrote in a research note on Wednesday.

Phintraco added that Iran’s closure of the Strait of Hormuz has created turbulence in global energy markets, with Asian economies expected to face the biggest impact due to their reliance on Middle Eastern oil supplies.

Across Asia, markets also tumbled as investors assessed the risks of supply disruptions in global energy trade.

South Korea’s Kospi led regional losses, falling heavily 9.6% to 5,235 by midday. Shares of Samsung Electronics slid more than 10%, while SK Hynix dropped 8%.

The Korea Exchange temporarily halted trading for the Kospi, while a circuit breaker was triggered on the tech-heavy Kosdaq after the index fell more than 8%.

In Tokyo, the Nikkei 225 dropped 3.9% to 54,090, reflecting concerns over Japan’s dependence on imported oil and natural gas from the Middle East.

Elsewhere, Hong Kong’s Hang Seng fell 2.8% to 25,037, while China’s Shanghai Composite slipped 1.3% to 4,069.