(RTTNews) - Preliminary data released by the University of Michigan on Friday unexpectedly showed an improvement in U.S. consumer sentiment in the month of December. "Gains in the sentiment index were seen across multiple demographic groups, with particularly large increases for higher-income families and those with larger stock holdings, supported by recent rises in financial markets," said Surveys of Consumers Director Joanne Hsu. "Declines in short-run inflation expectations were visible across the distribution of age, income, education, as well as political party identification," said Hsu.