* Euro zone to seek Greek aid deal without write-off
* Separatist parties win Catalonia election
* Knight in talks for market-making unit sale- sources
* Futures lower: S&P 6.5 pts, Dow 44 pts, Nasdaq 8.5 pts
By Angela Moon
NEW YORK, Nov 26 (Reuters) - U.S. stock index futures fell on Monday as investor returned to the market after a holiday-shortened trading week, focused on the meeting of euro zone finance ministers on Greece and negotiations over the U.S. "fiscal cliff."
Euro zone finance ministers and the International Monetary Fund will seek to unfreeze the second bailout package for Greece on Monday, but they first need to agree if some of the official loans to Athens might eventually be forgiven to cut Greek debt.
U.S. lawmakers have made little progress in the past 10 days toward a compromise to avoid the harsh tax increases and government spending cuts scheduled for Jan. 1, a senior Democratic senator said on Sunday.
"On the most pressing issue for the markets into year end, that of the tax and spending issues in the U.S., the Sunday morning talk shows didn't reveal that we're on the cusp of a deal as more horse trading will go on in the weeks to come," said Peter Boocvkar, managing director at Miller Tabak & Co in New York.
S&P 500 futures lost 6.5 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 fell 44 points, and Nasdaq 100 futures dropped 8.5 points.
Knight Capital Group Inc is in talks about possibly selling its market-making operation, its largest and most profitable business, but it is not known if a deal will happen, sources familiar with the matter said on Saturday.
Apple Inc has asked a federal court to add six more products to its patent infringement lawsuit against Samsung Electronics Co, including the Samsung Galaxy Note II, in the latest in move in an ongoing legal war between the two companies.
U.S. shoppers went to stores earlier this Thanksgiving weekend and bought online more than in years past, giving retailers a strong start to the holiday shopping season, data showed on Sunday.
Black Friday's online sales topped $1 billion for the first time ever as more consumers used the Internet do their early holiday shopping, comScore Inc said on Sunday.
European equities inched lower following last week's strong rally in morning trade on Monday while the euro hovered near a one-month peak against the dollar as investors awaited the outcome of talks to provide a new tranche of emergency loans to Greece.
Over the weekend, separatist parties from Spain's Catalonia region won almost two-thirds of seats in the local parliament, backed by voters frustrated over the country's economic crisis and a tax system seen as unfair to the wealthy region.
European banks have asked the European Commission to postpone the introduction of tougher global bank capital rules by a year to 2014 after U.S. regulators delayed application of the new requirements.
U.S.-based stock funds suffered the most outflows since late July as U.S. lawmakers inched ahead in talks to avert the "fiscal cliff" of tax hikes and spending cuts set to occur in January, data from Thomson Reuters' Lipper service showed on Friday.
U.S. stocks rose for a fifth day during a holiday-shortened, thinly traded session on Friday as investors picked up recently beaten-down shares of large technology companies.