Stock index futures rose slightly on Tuesday as investors were encouraged by strong earnings from companies, including economic bellwether United Parcel Service.

UPS, the world's largest package delivery service, reported a nearly 10 percent drop in fourth-quarter profit, but results beat expectations. The stock rose 1.4 percent to $59.20 in premarket trade.

This week I think people are starting to look at the fact that we've had one of the best earnings seasons in a while, said Art Hogan, chief market analyst at Jefferies & Co in Boston.

Homebuilder D.R. Horton Inc posted its first quarterly profit in almost three years, helped by a large tax credit, beating estimates and sending its shares up 7.5 percent to $12.80 in premarket trade.

S&P 500 futures rose 2.1 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures gained 30 points, and Nasdaq 100 futures added 3.25 points.

According to the latest available Thomson Reuters data, 77 percent of the S&P 500 companies reporting so far have beaten estimates.

Investors will also eye White House adviser Paul Volcker's testimony before a Senate panel urging lawmakers to curb risks taken by large banks.

Volcker is expected to tell the Senate Banking Committee that commercial banks' proprietary and speculative activities should not be protected by the government, according to testimony obtained by Reuters. His comments could hurt bank stocks, which tumbled when reports on the proposal broke last month.

Redbook releases its retail sales index of department and chain store sales for January at 8:55 a.m. EST, while the National Association of Realtors will issue pending home sales for December at 10 a.m. Economists surveyed by Reuters expect a 1.0 percent rise compared with a 16.0 percent fall in the previous month.

U.S. stocks rose on Monday as better-than-forecast data from the manufacturing sector and earnings from Exxon Mobil Corp revived bullish sentiment.

(Editing by Jeffrey Benkoe)