The Dow ticked down marginally, while the S&P and Nasdaq each lost about a tenth of a percent.

U.S. labor data so far this week has been mixed.

Initial jobless claims on Thursday pointed to a still-strong labor market, while private payroll growth a day earlier reflected a potential slowdown.

Friday's non-farm payrolls for September could be the week's most important economic news, as investors remain concerned about whether the Federal Reserve will keep rates higher for longer, says Joy Yang, Head of Product Management and Marketing at MarketVector Indexes.

"This is kind of the story that we've seen over the last few weeks, is that this is still a very macro-sensitive environment where people are still looking at news and still trying to anticipate what the Fed news will be. So, you know, we got the message, higher for longer, and I think it's beginning to hit investors now that they're recognizing that if they have to sustain their positions for longer, and then they have to be more cautious."

Among the day's movers, Clorox dropped more than 5% after the bleach company said it expects to post a first-quarter loss.

And shares of Dell were down 1.5% after the tech company's revenue forecast signaled that an AI boost may take longer to materialize.

Investors are looking for third-quarter earnings reports, which kick off mid-month, to reverse recent market weakness.