Direct answer: Based on the latest publicly reported coverage, today’s broad market pullback was driven chiefly by a renewed concern over high valuations in technology and AI-related stocks, fading expectations for imminent rate cuts from the Federal Reserve, and cautious sentiment after the end of the government shutdown, which delayed key economic data. The combination of richer-than-expected tech valuations, regulatory or geopolitical worries around AI and semiconductors, and the prospect of slower economic data has sparked a risk-off move across equities, with momentum crowded into a harsher sell-off in major tech names and related indices.

If you’d like, I can summarize the key factors cited by major outlets today (e.g., tech sector leadership, AI stock valuations, rate-cut expectations, and data delays) and track how the situation evolves over the next trading sessions.