United Microelectronics Corp (UMC) experienced a significant 24-hour decline of 5.11%, reflecting broad selling pressure in the semiconductor sector and investor profit-taking following a recent rally.

The drop comes amid widespread weakness across the chip industry, with major peers also facing downward pressure. UMC's retreat appears to be a correction after the stock surged over 10% following strong first-quarter results, which showed net profit soaring 108% year-over-year.

Analysts note that the stock's valuation has become stretched, with its trailing price-to-earnings ratio rising to 36.7 times, significantly above its five-year median of 11.8 times. This elevated valuation, combined with sector-wide headwinds, prompted investors to take profits, leading to the sharp decline over the past 24 hours.