Samsung Electronics, SK Hynix shares tumble over 9% as chip rout spreads from Wall Street

Shares of Samsung Electronics and SK Hynix plunged Thursday, dragging down South Korea's benchmark Kospi after the tech-heavy Nasdaq Composite slumped overnight.

Samsung Electronics tumbled more than 7% while SK Hynix sank over 9% at the open, wiping out billions in market value as Asia's largest chipmakers bore the brunt of the global tech selloff.

SK Square, the largest shareholder of SK Hynix, fell 13.2% to 1,525,000, mirroring broader losses across the semiconductor sector.

Samsung Electronics fell 9.06% to 286,000 while SK Hynix dropped 14.57% to 2,187,000, finishing the session sharply lower.

Samsung and SK Hynix now make up around half the Kospi's total weight, up from around just a quarter at the end of last year," Zavier Wong, market analyst at eToro, said in a note, highlighting the heavyweights' massive influence on the country's benchmark index.

"A sharp move in either name drags the whole index with it before the other roughly nine hundred listed companies get a say."

Hong Kong and Chinese tech stocks also saw a widespread sell-off, extending the regional downturn. The Hong Kong-listed shares of Semiconductor Manufacturing International Corporation, China's largest contract chipmaker and foundry, fell more than 11%, while Hua Hong Grace, another Chinese semiconductor foundry listed in the city, tumbled 14%.

Knowledge Atlas Technology, the Hong Kong-listed entity behind Chinese AI model developer Zhipu, plunged more than 17% while chip firm Shanghai Iluvatar CoreX Semiconductor was down nearly 18%.

The selloff in Asia tracks a dismal start to July for the Nasdaq as investors aggressively dumped chip stocks.

In Wednesday's session on Wall Street, Micron Technology shares dived more than 10%, despite its stunning 260% gain year-to-date, while Sandisk also shed over 10% overnight.

Other mega-cap tech heavyweights, including Nvidia and Broadcom, joined the decline, falling between 1% and 2%.

SK Hynix Chief Executive Officer Kwak Noh-jung said earlier Thursday the company plans to invest 100 trillion Korean won ($64.37 billion) in South Korea, with construction of its M17 fabrication plant set to begin next year and operations targeted for the first half of 2029 in the country's central Chungcheong region.

Under the plan, the chipmaker will allocate 80 trillion won to its M17 chip manufacturing plant, which will produce NAND flash memory used in storage devices, and 20 trillion won to the P&T7 facility to expand technology for combining and assembling advanced chips.

"These investments are aimed at meeting the soaring demand for HBM servers and DRAM, as well as enterprise SSDs and NAND, as AI services take off," Kwak said during a public briefing in Asan, a city south of Seoul, while outlining SK Hynix's latest expansion plan.

HBM, or high-bandwidth memory, is an advanced memory chip used in artificial intelligence systems, while DRAM is the main type of memory used in computers and servers. Enterprise solid-state drives, or SSDs, are storage devices designed for data centers.

Kwak also noted SK Group, South Korea's second-largest conglomerate and the parent company of SK Hynix, plans to expand its AI data center infrastructure nationwide, alongside its semiconductor production hubs.

"We plan to build AI data centers across the country in phases, starting with an initial capacity of 5 gigawatts (GW) and eventually scaling up to 15 GW," the CEO explained.

This announcement came just days after the South Korean government announced major investment initiatives on Monday aimed at supporting the country's AI ambitions, including plans for Samsung Electronics and SK Hynix to invest a combined 800 trillion won as part of a national semiconductor ecosystem project.

SK Hynix is also set to begin trading American depositary receipts on the Nasdaq on July 10, expanding access for U.S. investors.