US shares boosted by improved GDP data
(Close): US shares were mixed at the close after the growth estimate for the fourth quarter of 2015 was revised up to 1% from 0.7%.
The tech-heavy Nasdaq index climbed 8.27 points to 4,590.47.
Shares in Caterpillar, the world's largest construction and mining equipment maker, were up 0.6%.
Earlier in the week, the company gave more details of a major restructuring, which will see it combine two divisions dealing with power and energy.