Driven by the strong performance of US memory-stock peers on July 21, the global semiconductor market saw a broad rebound on July 22. The US memory-stock sector rose by more than 10% in nearly all cases: SanDisk surged by over 14% to lead the group, SK hynix rose by over 13%, and Micron Technology jumped by over 12%, with its market cap returning to the trillion-dollar level. In Hong Kong equities, the Southern 2x long Hynix ETF rose by nearly 15%.
US Stock After-Hours Memory Stock Market Snapshot
On the July 21 US after-hours session, the memory sector rose in nearly all cases by more than 10%. The gains for three key targets were as follows:
SanDisk: up over 14%, leading the memory sector
SK hynix (US-listed): up over 13%
Micron Technology: up over 12%, with market cap back above the trillion-dollar mark
Hong Kong: Southern 2x long ETF price action: Hynix up nearly 15%, Samsung Electronics up over 10%
Fueled by the US after-hours move, Hong Kong memory-related leveraged ETFs also climbed sharply: the Southern 2x long Hynix ETF rose by nearly 15%, and the Southern 2x long Samsung Electronics ETF gained over 10%.
Korean Stock KOSPI Rebounds and Sidecar Mechanism Activated
On July 22, 2026, South Korea’s composite stock index (KOSPI) rose in tandem, reclaiming the 7,000-point level and once pushing higher by more than 6% to above 7,100 points; SK hynix was up more than 9% at one point in the Korean market, and Samsung Electronics was up more than 6% at one point.
Because the KOSPI 200 futures index rose by more than 5% and remained elevated for over a minute, the Korea Exchange, in accordance with regulations, activated the Sidecar mechanism at 9:06 AM local time, pausing KOSPI’s programmatic buy orders for 5 minutes to cool the market; the Sidecar mechanism is automatically triggered by the exchange when index futures experience sharp swings in a short period to prevent programmatic trading from exacerbating volatility.
Cathay Haitong Analysis: The Slowing Pace of Memory Gains Has Been Fully Priced In
In its latest analysis, Cathay Haitong of China said market expectations for a slowdown in memory price gains have already been fully priced into current valuations, and the market has far from fully reflected the persistence of the business cycle. The firm believes recent pullbacks in memory stocks present an opportunity to set up positions, rather than a top-signal.
FAQ
Which US memory stocks saw the biggest gains on the July 21 US after-hours session?
According to reports, SanDisk rose by over 14% to lead the group, SK hynix rose by over 13%, and Micron Technology rose by over 12%, with its market cap returning to the trillion-dollar level; the memory sector rose by more than 10% in nearly all cases.
What is the Sidecar mechanism for Korea’s KOSPI, and when was it triggered on July 22?
The Sidecar mechanism is automatically launched by the Korea Exchange when the KOSPI 200 futures index rises by more than 5% and remains above that level for over a minute, pausing KOSPI’s programmatic buy orders for 5 minutes to cool the market; on July 22, 2026, the mechanism officially started at 9:06 AM local time.
Why did the July 22 gains for the Southern 2x long Hynix ETF in Hong Kong equities come in at what level?
According to reports, on July 22 the Hong Kong Southern 2x long Hynix ETF rose by nearly 15%, and the Southern 2x long Samsung Electronics ETF rose by over 10%, tracking the broad rally in the US after-hours memory sector.
