Are Google, Facebook, Twitter, and Amazon "data brokers" according to the FTC?

Not very clear, see here.

Data Brokers: A Call for Transparency and Accountability

FTC Report, here. Statement of Commissioner J. Brill, here

Amazon Strategy Raises Hackles in Germany

NYTimes, here. 

The right to be forgotten and open data

OKF blog, here.

Old friends in new frocks? MFN clauses in the online hotel booking sector/18

(Previous installments here)

Finally, and more generally, it would be unreasonable to turn a blind eye to the fact that the economic value extracted from consumers’ personal data is essential to many Internet entrepreneurs. Safeguarding competition in an era of big data requires a detailed understanding of how exactly user information fits into these firms’ business models.