Shares of prominent US auto makers and car parts manufacturers were mostly higher in early afternoon trade, after JP Morgan auto analyst David Bradley upgraded the sector to a 'market weight' rating, dealers said.

Share prices were higher in early trade after changing direction several times in uncertain price action, as investors reviewed a new set of technology sector research notes and a defense industry takeover offer, dealers said.

Trading opened flat on the Nasdaq composite and slightly lower on the DJIA.

The FBI believes a retired US Air Force sergeant they have arrested on spying charges tried to share sensitive defence secrets with Libya.