The KOSPI Composite Index fell more than 1% to below 5,100 on Thursday, retreating from record highs as investors began locking in profits following a relentless rally. Despite the pullback, the benchmark index remains up about 20% year-to-date, significantly outperforming many of its global peers. Samsung Electronics declined 1% on Thursday, while SK Hynix erased earlier gains to trade 0.2% lower. Both companies had been at the forefront of the recent rally, driven by robust demand for chips and memory from artificial intelligence servers and data centers. Strong earnings further supported the gains, with Samsung Electronics making history as the first domestic corporation to surpass 20 trillion won in quarterly operating profit. Meanwhile, investors continued to weigh trade uncertainties in the backdrop, following tariff threats from US President Donald Trump, although discussions aimed at resolving these issues are reportedly underway.