Having to enact a layoff to deal with 400 people when you already have a reputation about being ruthless with "up or out" is interesting though. As I understand it, it's not hard to fire deadwood at Amazon. So why risk the PR hit with "layoffs"? Seems curious.
400 would be about 1%, which would be fairly reported as a few hundred. My ceiling number is very high, but I would believe more than 1% are let go.