US STOCKS-Futures build on 'cliff' rally ahead of data
* Jobless claims, GDP, home sales data on tap
* Italian 10-yr yield at lowest in two years
* Tiffany shares slide premarket after results
* Futures up: Dow 78 pts, S&P 8.6 pts, Nasdaq 19.5 pts
NEW YORK, Nov 29 (Reuters) - U.S. stock index futures advanced on Thursday, building on the previous session's steep gains, on expectations of progress toward reaching a fiscal agreement in Washington.
* Markets will continue to focus on discussions in Congress to avoid big spending cuts and tax hikes - dubbed the "fiscal cliff" - and equities may retreat, as they did Tuesday, if the upbeat negotiation environment in Washington shifts.
* Investors await data, including the second estimate of third-quarter gross domestic product, due at 8:30 a.m. ET (1330 GMT). Economists in a Reuters survey forecast a 2.8 percent annualized pace of growth, compared with a 2.0 percent rate in the first estimate.
* The Commerce Department will issue preliminary corporate profits for the third quarter at 8:30 a.m. (1330 GMT). At the same time, the Labor Department will release first-time claims for jobless benefits; 390,000 new filings are forecast, compared with 410,000 in the prior week.
* The yield on Italy's 10-year bonds fell to the lowest in two years at an auction, amid relief that immediate risks over Greece had diminished.
* S&P 500 futures rose 8.6 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 rose 78 points, and Nasdaq 100 futures added 19.5 points.
* Also due for release Thursday are pending home sales for October at 10:00 a.m. (1500 GMT) and the Federal Reserve Bank of Kansas City November manufacturing survey at 11:00 a.m. (1600 GMT).
* Tiffany shares tumbled more than 12 percent in premarket trading after the upscale jeweler reported quarterly results and lowered its full-year sales and profit forecasts.
* Kroger, the biggest U.S. supermarket operator, is also due to report third-quarter earnings.
* On Wednesday, the Dow Jones industrial average rose 106.98 points, or 0.83 percent, to 12,985.11. The S&P 500 gained 10.99 points, or 0.79 percent, to 1,409.93. The Nasdaq Composite added 23.99 points, or 0.81 percent, to close at 2,991.78.