The tech-heavy Nasdaq index in the US saw sharp declines as internet stocks faltered for a second day on concerns about increased regulation, while chipmaker stocks slid on signs of flagging demand.

US stocks went on another dizzying ride as they worked their way back from an early-morning plunge to send the Standard & Poor's 500 index to its first gain in four days.

US stocks climbed on Wednesday as investors cheered a report of stronger economic growth. Technology companies, retailers and travel providers all made solid gains.

US stock indexes edged lower for the second day in a row as a sharp drop for banks and a rare loss for technology companies cancelled out gains for drug makers and consumer-focused companies.