[Digital Today reporter Sang-yeop Oh (오상엽)] The KOSPI slid more than 4 percent intraday on the fallout from a sharp fall in U.S. AI and technology shares including Alphabet. Foreign selling widened, led by big semiconductor names, triggering a sell sidecar on the main board for the first time in 11 sessions.

As of 10:06 a.m. on Oct. 30, the KOSPI was down 272.63 points, or 4.59 percent, from the previous session at 5,665.03.

A sell sidecar was also triggered on the steep drop. The Korea Exchange suspended the effectiveness of program sell orders on the main board for five minutes at 10:04:55 a.m. after KOSPI200 futures fell 5.12 percent to 887.92 from the base price of 935.84.

It was the first KOSPI sell sidecar since Oct. 15, 11 sessions ago. At that time, renewed concerns over profitability in the AI industry sent the KOSPI tumbling more than 7 percent, triggering a sell sidecar and circuit breakers in succession.

By investor category, foreigners were net sellers of 312.2 billion won and institutions were net sellers of 189.1 billion won. Retail investors were net buyers of 440.2 billion won, absorbing supply.

Losses were widening among top market-cap stocks, led by semiconductor shares.

SK Hynix was trading at 1,394,000 won, down 8.65 percent from the previous session, while Samsung Electronics was down 5.17 percent at 220,000 won.

SK Square was down 8.08 percent and Samsung Electro-Mechanics fell 9.28 percent. Hyundai Motor was down 3.25 percent, KB Financial Group fell 3.00 percent and Samsung Life Insurance was down 5.58 percent.

By contrast, LG Energy Solution was up 0.84 percent and Samsung Biologics rose 3.95 percent.

The steep drop in local stocks was influenced by weakness in U.S. technology shares a day earlier. In New York on Oct. 29, local time, Google parent Alphabet plunged 12.64 percent on weak third-quarter revenue and worries over rising AI investment costs. The tech-heavy Nasdaq index fell 1.38 percent.

Semiconductor shares also weakened. The Philadelphia Semiconductor Index fell 1.42 percent, while Micron slid 4.98 percent, AMD fell 2.08 percent and SK Hynix's U.S.-listed depositary receipts dropped 1.58 percent. After the close, Intel and Amazon also showed weakness in after-hours trading on disappointment over earnings outlooks.

As concerns grow again over whether large-scale AI investment can translate into actual profits, profit-taking also appears to be widening in South Korea, led by semiconductor shares that have risen sharply in recent weeks.