Stock index futures pointed to a higher open on Tuesday as optimism grew that the Greek parliament would adopt a deeply unpopular austerity plan, easing concerns about a debt default.

There's some follow-through from yesterday's gains on the expectation that the measures are going to pass, said Scott Armiger, portfolio manager at Christiana Trust in Greenville, Delaware.

S&P 500 futures rose 5.2 points and were slightly 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 41 points, and Nasdaq 100 futures were up 9 points.

Wall Street rallied after three days of losses on Monday, led by bank stocks after news of more favorable capital requirements and optimism over Greece's austerity plan.

Futures were flat for most of the early morning, but rose alongside crude oil futures, with U.S. crude gaining 1.1 percent on bets the Greek plan would be passed. Exxon Mobil Corp rose 0.7 percent to $78.44 before the bell.

Greek lawmakers will vote Wednesday and Thursday on the austerity measures, which must be passed in order to receive the next payment of its bailout.

If the government does not get the next tranche, analysts said Greece could default on its debt, possibly sparking a Europe-wide crisis and potential credit market freeze similar to the one that came after the Lehman Brothers collapse.

Armiger said stock gains may not last throughout the day. Unlike earlier this year, lately when we've seen a rally, that has been followed by a setback of equal or greater size.

Concerns over a euro zone crisis have contributed to S&P 500 losses of more than 6 percent since the start of May. A thinly traded rise of almost 1 percent Monday could mean limited upside from current levels.

In a sign of stabilization in the housing market, U.S. single-family home prices dipped modestly in April, at the start of the spring buying season, according to the S&P/Case-Shiller index.

The data barely affected futures. Coming later are readings on consumer confidence and the Richmond Fed manufacturing services index at 10 a.m. EDT (1400 GMT). Confidence is seen holding roughly steady from the previous month.

Microsoft Corp late Monday said it was making a big move into cloud computing this week by taking the wraps off a revamped online version of its hugely profitable Office software later in the day. Shares of the Dow component rose 0.7 percent to $25.38 in premarket trading.

Nike Inc reported fourth-quarter earnings that beat expectations late Monday, and orders suggested robust strength for the future. The stock surged 4.6 percent to $85.35 before the bell.

(Editing by Jeffrey Benkoe)