U.S. stocks opened slightly lower on Tuesday (November 27) as worry over the threat to the economy posed by the "fiscal cliff" offset optimism from a deal to ease Greece's debt burden.

The Conference Board released a report that showed consumer confidence rose to a four-and-a-half-year high in November as consumers became more optimistic about the outlook for the economy.

In a separate report, the S&P/Case Shiller composite index revealed that single-family home prices rose in September for an eighth straight month in a further sign that the housing market is on the mend.

The Dow Jones industrial average dropped 33.02 points, or 0.25 percent, to 12,934.35. The Standard & Poor's 500 Index shed 2.58 points, or 0.18 percent, to 1,403.71. The Nasdaq Composite Index lost 4.07 points, or 0.14 percent, to 2,972.71.