* Moody's cuts France credit rating
* Hewlett-Packard tumbles after results
* Housing starts data expected
* Futures: Dow off 21 pts, S&P off 1.8 pts, up Nasdaq 3.25 pts
By Chuck Mikolajczak
NEW YORK, Nov 20 (Reuters) - U.S. stock index futures dipped on Tuesday, indicating the S&P 500 index may snap a two-day rally, after a credit downgrade of France by ratings agency Moody's and weak earnings by Hewlett-Packard.
The benchmark S&P index had risen more than 2 percent in the previous two sessions, spurred by optimism a deal could be reached to stave off the looming U.S. "fiscal cliff," a series of tax and spending changes next year that could derail the economic recovery.
Moody's Investors Service cut France's sovereign rating by one notch to Aa1 after the market's close on Monday, citing an uncertain fiscal outlook as a result of the weakening economy.
While the move was expected after Standard & Poor's issued a similar downgrade in January, the Moody's decision was a reminder of the headwinds buffeting the global economy and the danger of contagion by the euro zone's debt crisis.
"The French lost their top credit rating. That is a negative not only for Europe but reminds people in the U.S. that all this talk about overcoming the fiscal cliff is still just talk. If actions aren't taken, we probably face similar issues here," said Rick Meckler, president of investment firm LibertyView Capital Management in Jersey City, New Jersey.
"The whole European crisis has been one where announcements as being resolved have been made many times, but concrete steps have yet to be put in place and the U.S. is at the beginning of that process, not at the end."
Economic data includes housing starts and permits data for October at 8:30 a.m. (1330 GMT). Economists in a Reuters survey forecast a 840,000 annualized rate versus 872,000 in September, and a total of 865,000 permits compared with 890,000 in the prior month.
Hewlett-Packard Co slumped 11.4 percent to $11.79 in premarket trade after the company posted quarterly revenue that fell short of Wall Street expectations as its share of the personal computer market shrank and printer sales declined.
Also in the euro zone, finance ministers will give a tentative go-ahead for the disbursement of 44 billion euros in emergency loans to Greece on Tuesday, but the money will only be paid on Dec. 5 if the country meets all remaining conditions.
The S&P 500 index had fallen 5.3 percent between election day and the start of the rebound as angst over a possible deal drove investors to sell stocks limit the impact tax of expected tax increases on capital gains and dividends.
President Barack Obama and congressional leaders hope to start serious negotiations after the Thanksgiving holiday on Thursday on avoiding the "fiscal cliff."
S&P 500 futures fell 1.8 points and were 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 lost 21 points, and Nasdaq 100 futures added 3.25 points.
At 12:15 p.m (1715 GMT), Federal Reserve Chairman Ben Bernanke speaks before the Economic Club of New York, a speech that may offer a fresh chance to gauge the Fed's appetite for more monetary stimulus. Market participants currently expect the Fed to step up asset purchases in 2013 after Operation Twist expires.
H.J. Heinz Co edged up 0.3 percent to $58.90 in light premarket trade after posting higher quarterly earnings, citing growth in emerging markets and a favorable tax rate.
Campbell Soup Co reported lower quarterly net earnings, hurt by charges related to its recent acquisition of Bolthouse Farms, but it stood by its full-year forecast.