U.S. stock index futures pointed to a mostly lower open Tuesday as shares of Apple dropped in premarket trading.

The iPhone maker's stock fell more than 2.5 percent in premarket trading following a report from Taiwan's Economic Daily, citing unidentified sources, that Apple will slash its sales forecast for the iPhone X by 40 percent in the quarter to 30 million units.

Apple has not publicly disclosed quarterly sales targets for the iPhone X, which went on sale in November. The company did not immediately respond to a CNBC request for comment.

Of the major U.S. stock indexes, only the S&P 500 was indicating a slightly higher open.

U.S. markets were closed Monday for the Christmas Day holiday. Major European markets remained closed Tuesday for the holiday.

In Asia, the Shanghai composite closed about three-fourths of a percent higher while Japan's Nikkei 225 fell 0.2 percent.

The S&P CoreLogic Case-Shiller 20-City Composite Home Price Index posted a 6.4 percent year-over-year gain in October, up from 6.2 percent the previous month, according to a Tuesday report.

Other U.S. economic reports expected Tuesday include the Richmond Fed manufacturing index and the Dallas Fed manufacturing survey. The Treasury is set to hold a 2-year Treasury note auction in the afternoon.

Treasury yields edged higher in early morning trade with the 2-year yield near 1.90 percent and the 10-year yield near 2.48 percent.

The U.S. dollar index traded little changed near 93.37 and the euro near $1.185. U.S. crude oil futures edged up to trade near $58.50. Gold futures rose 0.4 percent to $1,283.80 an ounce.

— Reuters contributed to this report.