A deepening global sell-off in semiconductor stocks is driving the technology sector lower, fueled by investor concerns over lofty valuations and the sustainability of the recent AI-driven market rally. The sell-off was intensified by a negative reaction to chip giant TSMC's latest results and capital expenditure plans, which has raised questions about returns on investment. This has triggered significant declines in major chip-related companies and is causing a broader re-evaluation of one of the market's most crowded trades.