ASE Technology's stock experienced a significant pre-market plunge of 5.06% on Tuesday, as the semiconductor company was caught in a broader sector sell-off combined with insider selling activity.

The decline was attributed to sustained selling pressure across the semiconductor industry, with major peers including Intel, Micron Technology, Advanced Micro Devices, NVIDIA, and Broadcom all posting declines in recent sessions. This systemic weakness in the sector continued to weigh on individual stocks like ASE Technology.

Adding to the downward pressure, company director Jeffrey Chen recently sold millions of dollars worth of shares on the open market. The large-scale insider disposal raised market concerns regarding management confidence and the company's outlook, amplifying the negative sentiment from the sector-wide weakness.