Wall Street ends lower on tech valuations, economic jitters

STORY: Wall Street's main indexes tumbled on Thursday, with the Dow dropping more than eight-tenths of a percent, the S&P 500 shedding over 1% and the Nasdaq losing nearly 2%.A resumption of Tuesday's tech selloff weighed on the Nasdaq, as investors worried about inflated AI-related stock prices. Michael Landsberg, chief investment officer at Landsberg Bennett Private Wealth Management, said that while tech earnings were mostly strong, foreward guidance from some AI darlings may have underwhelmed investors."I think a lot of the tech earnings, basically everyone's expecting a beat and a raise. So what you're seeing is you see the beats, but if they're not aggressively raising, I think that's where some of the stocks are getting kind of beaten up. Because valuations are so, you know, priced to perfection, if you will. So I think you're seeing that."The Philadelphia SE Semiconductor index dropped nearly 2.5%, with Nvidia and Qualcomm losing more than 3.5% and AMD plunging over 7%.Among other movers, shares of DoorDash slumped 17.5% after the delivery firm reported third-quarter profit below Wall Street expectations on rising expenses.Shares of Elf Beauty plummeted 35% after the cosmetics-maker forecast annual sales and profit below expectations.On the flip side, shares of Snap jumped more than 9.5% after the social media firm beat third-quarter revenue estimates and announced a partnership with software company Perplexity AI.