The GDP estimates released are based on more complete source data than were available for the advance estimates issued last month. In the advance estimates, the decrease in real GDP was 0.3 percent.
 
The decrease in real GDP in the third quarter primarily reflected negative contributions from personal consumption expenditures (PCE), residential fixed investment, and equipment and software that were partly offset by positive contributions from federal government spending, private inventory investment, exports, nonresidential structures, and state and local government spending. Imports, which are a subtraction in the calculation of GDP, decreased.
 
Most of the major components contributed to the downturn in real GDP growth in the third quarter. The largest contributors were a sharp downturn in PCE, a deceleration in exports, a smaller decrease in imports, and decelerations in nonresidential structures and in state and local government spending. Notable offsets were an upturn in inventory investment and an acceleration in federal government spending.

More details here.