South Korean market regulators stepped in on Monday after a sharp early decline triggered a temporary halt on program-based sell orders. The action came after futures linked to the Kospi 200 dropped more than 5%, activating a market safety mechanism known as a “sidecar” for the first time since April.
The Kospi had fallen more than 5% in early trade as heavy algorithmic and arbitrage-driven selling intensified losses. Under exchange rules, authorities can suspend program sell orders when declines breach predefined thresholds. The objective is to prevent automated trading strategies from amplifying panic-driven moves and to allow markets time to stabilise.
Program trading includes index arbitrage and algorithmic strategies that react instantly to price moves. During periods of heightened stress, such trading can accelerate declines within minutes. Monday’s halt reflected concerns that machine-led selling was worsening the slide rather than reflecting fundamental investor decisions.
The fall in South Korea was led by large semiconductor stocks. Samsung Electronics and SK Hynix dropped between 4.8% and 6.5%, as sentiment toward AI-linked shares weakened. Recent U.S. earnings from technology companies have raised questions about rising costs and the near-term returns from heavy investments in artificial intelligence, prompting investors to reassess valuations in the sector.
Sell-off in Asian Markets
The weakness in Seoul mirrored a broader sell-off across Asian markets. In Hong Kong, the Hang Seng Index fell 2.5% while the Hang Seng TECH Index dropped more than 3%. Japan’s Nikkei 225 declined 1%, Australia’s S&P/ASX 200 slipped 1.3%, and Singapore’s Straits Times Index edged lower by 0.3%.
Mainland Chinese markets were also under pressure. The CSI 300 fell 1.1% and the Shanghai Composite dropped 1.3%, weighed down by concerns around soft domestic demand signals.
Futures tied to the Nasdaq-100 were down around 1% during Asian trading hours, indicating that weak sentiment from Wall Street’s technology-heavy index was feeding into regional markets.
Adding to global uncertainty, U.S. President Donald Trump nominated Kevin Warsh as the next Federal Reserve chair. Warsh is widely regarded as hawkish, reviving concerns that tighter monetary conditions could persist and weigh on risk assets worldwide.
