Dow jumped 421 points, showing how sensitive markets remain to every move in the AI supply chain. The Nasdaq dipped 0.1%, a modest but meaningful reversal after its strongest day since mid-May. Traders had pushed AI stocks higher earlier in the week, but momentum faded once competition in the chip space resurfaced. The move reflects a market that is still sensitive, valuation-focused, and deeply influenced by a handful of mega-cap players. When those stocks wobble, the entire index feels it.Nvidia dropped m ...