Samsung Electronics, SK hynix become day-traders' playground as shares gyrate

"Buy Thursday, sell Thursday." — retail investor on Samsung Electronics and SK hynix

"September is a range-bound market. Day trading is the only way to survive." — retail investor

Retail investors are piling into same-day buying and selling of Samsung Electronics and SK hynix shares as the two semiconductor giants continue a pattern of modest gains followed by sharp reversals.

Samsung Electronics closed Thursday down 0.20 percent at 250,000 won ($183), while SK hynix fell 1.05 percent to 1.596 million won. Both stocks had risen about 2 percent in early trading before abruptly turning lower in the afternoon, ultimately extending their recent losing streak. The two had already tumbled more than 4 percent the previous session. Share prices that investors had expected buybacks to support instead fell further.

Growing interest rate concerns entering September have left the broader market without a clear direction. Brokerages are forecasting a range-bound Kospi in September, with the index expected to oscillate between 6,300 and 7,500.

The lack of market direction is drawing more retail investors toward short-term trading.

According to Korea Exchange data released Thursday, SK hynix's average daily share turnover rate in August reached 11.4 percent — more than 1.5 times the level recorded in the same month a year earlier. Samsung Electronics' turnover rate also rose from 4.7 percent to 7.8 percent over the same period, a 1.6-fold increase.

The surge in day trading reflects heightened volatility in large-cap semiconductor stocks amid the absence of a clear market leader, stoking demand for short-term plays.

Market watchers attribute the Kospi's failure to break above 7,000 to several factors: volatility in long-term interest rates, supply-demand pressures in the semiconductor sector, and an elevated risk premium following the sharp sell-off in July. The concentration of retail investors' accumulated buy positions in a narrow price range has also been cited as a drag.

Kiwoom Securities said retail investors have accumulated net purchases of about 110 trillion won above the 7,000 level, and that a rebound in the index would likely trigger selling pressure driven by break-even psychology. "The first resistance zone sits between 7,000 and 7,500, where about 20 trillion won in overhang is concentrated," the brokerage said, "while the more significant second resistance zone around 8,000 holds as much as 72 trillion won."

Kiwoom added that pushing the index higher would require not only sustained earnings improvement but also sufficient buying momentum from foreign and institutional investors to absorb the retail overhang accumulated in that range.