The five best performers so far this year are Roundhill Generative AI & Technology ETF ( CHAT 1.17%), VanEck Semiconductor ETF, WisdomTree Artificial Intelligence and Innovation Fund ( WTAI 1.43%), ...

"Breadth, or the number of stocks participating in gains, remains mostly concentrated in Big Tech stocks tied to AI," said Anthony Saglimbene, Ameriprise's chief market strategist, in a note Monday.

A global selloff in stocks extended into a fourth day as investors, concerned about lofty tech valuations, shifted away from ...