WASHINGTON (MarketWatch) - The U.S. economy contracted at a 0.5% annual rate in the third quarter, slower than the negative 0.3% estimated a month ago, the Commerce Department reported Tuesday. The revisions to real gross domestic product were largely due to weaker consumer spending. Economists were predicting a revision to about negative 0.6%. The core personal consumption expenditure price index rose 2.6%, compared with the initial estimate of a 2.9% gain.