US stocks-S&P 500, Dow set to open lower as Gulf tensions send oil to over six-week high

The benchmark S&P 500 and the blue-chip Dow indexes were on course to open lower on Tuesday as fresh hostilities in the Middle East pushed oil prices to their highest since late July, while markets await inflation data due later this week.

The declines follow a roller-coaster stretch that saw investors rushing to readjust rate-hike expectations after commentary from Federal Reserve Governor Christopher Waller and a stronger-than-expected jobs report.

The truncated week after the Labor Day holiday will be dominated by the Consumer Price Index report due on Friday and the Producer Price Index reading on Thursday.

Some investors have said inflation readings will hold more weight for the Fed's rate trajectory, given Chair Kevin Warsh's focus on bringing prices down.

"It still seems to be a bit of a wild card out there. Warsh is not as easily readable as his predecessor Jerome Powell was," said Michael Matousek, head trader at U.S. Global Investors. With oil potentially climbing further, market volatility could persist, he added.