US equity futures were flat but trending slightly lower after spending much of the premarket in the red amid low trading volume, a shortened year-end holiday week, and anxiety over the release of the minutes from the Federal Reserve's latest policy meeting.

Dow Jones Industrial Average futures, S&P 500 futures, and Nasdaq futures were all down by 0.01%.

The Federal Reserve is to release notes from the Dec. 9-10 Federal Open Market Committee meeting at 2 pm ET. The notes will be analyzed for clues about the direction of interest rate policy in the coming year.

Oil continued to climb following reports of Venezuela cutting production under US military pressure. US West Texas Intermediate crude rose 0.5% to $58.38 per barrel while benchmark North Sea Brent crude was up 0.5% to $61.78 per barrel.

The S&P Cotality Case-Shiller home price index for October is expected to be released at 9:00 am ET, before the opening bell. Analysts expect a modest increase of 1.1% from a year earlier.

The Chicago purchasing managers' index for December is expected to be released at 9:45 am ET, shortly after the opening bell, with investors hoping for steady economic growth. Analysts expect an index reading of 40, up from 36.3 a month earlier.