* Retailers hopeful over holiday shopping season
* Lisbon denies report of pressure to seek bailout
* Futures down: Dow 90 pts; S&P 11.5 pts; Nasdaq 19.5 pts
By Rodrigo Campos
NEW YORK, Nov 26 (Reuters) - U.S. stock index futures fell on Friday ahead of a shortened post-holiday session as investors fled from risk on worries that euro zone debt problems may spread.
* European shares dropped 1.2 percent after a German newspaper reported that a majority of euro zone members and the European Central Bank were pressuring Lisbon to seek a bailout. Portugal and the European Commission denied the report.
* China warned against military acts near its coastline ahead of U.S.-South Korean naval exercises that North Korea said risked pushed the region towards war, further rattling investors. The North shelled a South Korean island earlier this week.
* Resource-related stocks will be in focus as key base metals prices fell, pressured by a rise in margin requirements by the Shanghai Futures Exchange that prompted liquidation of speculative positions.
* Investors will also eye consumer-related stocks as so-called Black Friday kicks off a holiday shopping season that retailers hope will be the strongest in three years.
* S&P 500 futures fell 11.5 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 dropped 90 points, and Nasdaq 100 futures lost 19.5 points.
* U.S. stock markets will close at 1 p.m. EST (1800 GMT) following the U.S. Thanksgiving holiday on Thursday.
* On Wednesday, Wall Street rallied as investors put aside worries about swirling global problems and focused on upbeat data on the labor market and consumer spending.