U.S. stocks remained lower in pre-market trade Tuesday, while European bourses also lost ground. S&P 500, Dow and Nasdaq 100 futures continued to trade lower vs. fair value. European markets lost ground. The euro fell after Fitch kept a negative outlook on Portugal's AA ratings following the country's announcement of new austerity measures on Monday. Fitch also said the U.K. government's current plan to cut the deficit by half over four years is