Wall St falls as Nvidia boost fades, caution sets in ahead of Powell speech

Wall Street's main indexes fell on Thursday, as an initial boost from Nvidia's stellar forecast fizzled out and investors turned cautious ahead of Federal Reserve Chair Jerome Powell's speech later this week that will offer clues on the interest rate path.

Shares of Nvidia (NVDA.O) pared much of their earlier gains and were last up only 1.4%, slipping from a record high of $502.66 hit earlier in the session.

Analysts pointed to profit-taking after a strong run of gains heading into the chip designer's second-quarter results.

"The entire market has been in 'sell the news' mode. (Nvidia) was an incredibly crowded long (position) as was technology in general, and traders were primed to sell initial up moves," said Michael James, managing director of equity trading at Wedbush Securities.