US Chips Fall 4%: What Monday Holds for Samsung and SK hynix

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Samsung Electronics and SK hynix fell sharply on Tuesday and Thursday this week, then rebounded slightly on Friday to end the week. But on Friday night the Nasdaq fell 2.1%, and KOSPI 200 night-session futures slid more than 3%. Based on the signals visible now, both stocks are likely to open lower on Monday. But since they are already 25–32% below their peaks, how far they fall is likely to depend on foreign trading after the open.

How Samsung Electronics and SK hynix traded this week

Here is each day, based on regular-session closing prices.

• Tuesday, October 13: Samsung Electronics -7.39%, SK hynix -10.09%
• Wednesday, October 14: Samsung Electronics unchanged, SK hynix -1.66%
• Thursday, October 15: Samsung Electronics -9.48%, SK hynix -11.06%
• Friday, October 16: Samsung Electronics +2.62% (215,500 won), SK hynix +0.79% (1,272,000 won)

On Thursday the KOSPI fell 7.57%, enough to trigger a circuit breaker. On Friday the KOSPI rose 2.05%, its first gain in eight trading days, but it won back only about a quarter of the previous day’s loss.

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Compared with their peaks, Samsung Electronics is 24.5% below its September 23 high of 285,500 won, and SK hynix is 31.9% below its September 21 high of 1,868,000 won.

What happened in the US market on Friday night

The Nasdaq fell 2.1%, and chip stocks fell further. Micron dropped 5.63% and AMD 5.95%, and the US semiconductor ETF (SOXX) lost 4.14%. SK hynix’s American depositary receipts (ADRs), listed in the US, were reported to have fallen 6.58%.

The decline was attributed to doubts about whether AI companies can keep borrowing to fund their data center investments. For memory makers such as Samsung Electronics and SK hynix, worries about how fast their customers invest are worries about orders.

As a result, December KOSPI 200 night-session futures traded at 854.45 early on October 17, more than 3% below the day session.

Monday’s outlook: the pattern after big drops in US chip stocks

Over the past two weeks, each time the US semiconductor ETF fell more than 2% in a day, both stocks fell even more the next day.

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• October 12 night, SOXX -2.60% → October 13, SK hynix -10.09%, Samsung Electronics -7.39%
• October 14 night, SOXX -4.50% → October 15, SK hynix -11.06%, Samsung Electronics -9.48%
• October 15 night, SOXX -0.91% → October 16, SK hynix +0.79%, Samsung Electronics +2.62%
• October 16 night, SOXX -4.14% → Monday, October 19: ?

This time’s overnight drop (-4.14%) is similar to the one the night before Thursday’s plunge (-4.50%). But on October 13 and 15 there was other bad news as well, such as heavy foreign selling and the release of US inflation data. So a drop of the same size cannot be assumed to repeat.

What could deepen the drop, and what could limit it

What could deepen the drop

• Night-session futures down 3%-plus, SK hynix ADRs down 6.58%: Monday’s opening prices are likely to be low.
• Foreign selling: foreign investors were net sellers of SK hynix again on Friday, extending their net selling to 16 straight trading days.
• The US semiconductor index has fallen for eight straight trading days: selling on the US side has not stopped yet.

What could limit the drop

• How far they have already fallen: the shares already dropped sharply on Tuesday and Thursday on the same US-driven worries.
• Foreign trading on Friday: foreign investors turned to net buying in Samsung Electronics, and their net selling of SK hynix was much smaller than the day before.
• Memory prices: DRAM spot prices have risen over the past month. On October 13 the spot price of 16Gb DDR5 was $59.9, up 10.2% in a month.

Three things to watch in Monday’s session

• The gap between the opening price and night-session futures: if the 9 a.m. opening prices fall less than night-session futures did (3%-plus), that is a sign of buying on the dip.
• Foreign trading in SK hynix: whether the 16-day run of net selling ends is the first condition for a rebound.
• What’s next on the calendar: SK hynix reports third-quarter results on October 28. Until then, US Big Tech earnings and the semiconductor index are likely to set the direction.

In short, Monday is likely to open weaker; whether the stocks fall as far as they did on Tuesday and Thursday will show in foreign trading after the open.

This post is an outlook based on information as of early October 17, 2026 (after the US close), and is not investment advice on any particular stock or product.

Frequently asked questions

Q1. How far could Samsung Electronics shares drop on Monday?

A1. The exact size cannot be known. Night-session futures point to a drop of 3%-plus, but in the actual session the stock could fall more or less, depending on trading by foreign and retail investors.

Q2. What are KOSPI 200 night-session futures?

A2. Futures on the KOSPI 200 index that trade at night, after the regular session ends. Because they trade while the US market is open, they are used as an early indicator of the mood in the Korean market the next day.

Q3. Why is SK hynix falling more than Samsung Electronics?

A3. In this decline, foreign selling has been concentrated more on SK hynix, and because memory for AI servers makes up a larger share of its business, it has reacted more sharply to worries about US AI investment. Its decline from its peak is also larger: 31.9% for SK hynix against 24.5% for Samsung Electronics.

Sources: Korea Exchange regular-session closing prices; US share prices: regular-session closes (adjusted); AP (October 16 New York close); Newspim and Seoul Economic TV (October 16 KOSPI close); Asia Business Daily and Seoul Finance (October 15 circuit breaker); Stockplus (KOSPI 200 night-session futures)

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Information only, not investment advice.