NPD: Xbox One and Xbox 360 were the top selling consoles for each generation in the US in December. 908k (Xbox One) and 643k (Xbox 360)
So 908,000 for the Xbox One and 643,000 for the Xbox 360. Not bad.
Also confirmed by another Microsoft worker's twitter, Aaron Greenberg.
#NPD reports Xbox One #1 selling console in Dec, 360 sold well too. Big thanks to our fans for all the support!