SK Hynix flash crash exposes Nextrade liquidity risks

SK Hynix shares briefly plunged by the daily limit in pre-market trading on Thursday, marking the chipmaker’s second near-30% flash crash on Nextrade within about ten days and intensifying scrutiny of thin liquidity on South Korea’s alternative stock exchange.

Eleven shares changed hands at 1.168 million won each at 8 am Seoul time on August 6, about 30% below the previous Korea Exchange closing price. The stock quickly recovered most of the loss and ended Nextrade’s 50-minute pre-market session down roughly 2%, indicating that the extreme opening price was not driven by a change in the company’s business outlook.

The episode echoed a July 28 disruption when a single SK Hynix share traded at 1.272 million won, nearly 30% below the preceding close. That transaction triggered a volatility interruption on Nextrade and transmitted the distorted price into cryptocurrency derivatives linked to the chipmaker.

A perpetual futures contract tracking SK Hynix fell about 19% during the first event. Almost $60 million of leveraged long positions were liquidated within minutes, leaving more than 900 traders with estimated realised losses of $17.4 million. The platform operating the contract later offered to compensate eligible customers and said it would reassess the way external prices were incorporated into its valuation mechanism.

Thursday’s plunge again occurred at the start of Nextrade’s pre-market window, when order books are typically shallower than during the main session. The exchange allows stocks to move as much as 30% above or below the previous Korea Exchange closing price, meaning a small order can reach the limit when few competing bids are available.

The trade underscored the distinction between a price that is technically valid and one that accurately reflects the market’s consensus. Electronic systems can treat an executed transaction as authoritative even when only a handful of shares are involved. Prices may then spread through data feeds, trading algorithms, structured products and blockchain-based markets before human dealers can assess whether the move is credible.

Nextrade launched in March 2025 as the first serious challenger to the Korea Exchange’s long-standing dominance. It attracted investors with lower fees and trading hours stretching from 8 am to 8 pm, compared with the shorter core session on the main exchange. Retail traders account for most activity on the platform, which has at times handled a substantial share of the country’s equity turnover.

Its expanded trading day has improved access and competition, but the two SK Hynix incidents highlight risks when extended hours are combined with fragmented liquidity. Order books can be especially vulnerable at the opening instant, when market makers have not fully populated bids and offers and overseas price signals may still be feeding into domestic systems.

Regulators and exchange operators now face pressure to consider safeguards based on trade size, available depth and deviation from a volume-weighted reference price. Measures could include auction-style openings, minimum order-value requirements, stronger market-maker obligations or delayed dissemination of extreme prices produced by very small transactions.

The disruption comes during an unusually volatile period for SK Hynix and South Korean technology shares. The chipmaker has been at the centre of investor enthusiasm over high-bandwidth memory used in artificial-intelligence accelerators, but its shares have also recorded repeated double-digit moves as traders reassess valuations and future demand.

SK Hynix reported a sharp year-on-year increase in quarterly profit, supported by high-bandwidth memory sales, yet the results fell short of elevated market expectations. The disappointment contributed to a broad sell-off that erased trillions of dollars from South Korean equities at its peak and pushed measures of expected volatility to exceptional levels.

Leveraged exchange-traded funds linked to SK Hynix and Samsung Electronics have amplified those movements. Authorities have halted new sales of some single-stock leveraged products and proposed tighter investment limits, larger minimum deposits and higher transaction costs after retail investors suffered heavy losses.

Research into the market turbulence has also raised concerns that predictable rebalancing by leveraged funds can encourage traders to buy or sell ahead of compulsory end-of-day transactions. Such feedback loops may magnify price changes even when there is little new information about a company’s operations.