U.S. stock index futures pointed to a flat open on Tuesday after data showed home prices rose for the fifth straight month in September, but the growth was less than expected.

According to the Standard & Poor's/Case-Shiller indexes, home prices posted their second quarterly increase in the latest sign the housing market continues to recover.

Earlier, the government said the U.S. economy grew at a 2.8 percent annual clip in the third quarter, revised down from 3.5 percent estimated last month. Analysts forecast 2.9 percent.

We are going into the holiday season and consumers are not losing value on their homes. Last Christmas, they were losing equity value on their homes at a 20 percent clip, said Craig Thomas, senior economist at PNC Financial Services in Pittsburgh.

S&P 500 futures rose 2.2 points and were modestly below 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 were up 8 points, and Nasdaq 100 futures added 1.75 points.

Hewlett-Packard Co reported a quarterly profit that matched its preliminary results late Monday, and said the economy remained challenging, but it saw signs of a recovery.

Earlier Tuesday, both Medtronic Inc and Dollar Tree Inc reported quarterly earnings that topped expectations.

(Editing by Jeffrey Benkoe)