Multiple shops increased TV prices this weekend

How does this work? I used to think large shops set prices independently, but a strange thing happened today Sunday 4 December 2016.

Amazon, BestBuy, Walmart, Beach Camera, and many others I'm sure, all increased 4K TV prices by $100 to $200. How did they make this happen, do they coordinate prices? Sony and Samsung brands were affected, probably all brands raised their prices. Did the brands do this - did they send out a notice on Saturday, or was this a pre-coordinated all-across-the board increase?

Here's one explicit example:
Sony XBR55X850D a 55" TV was sold at $898 in all those shops, until Saturday Dec 3, 2016.
On Dec 4, all these shops, within a period of just 12-24 hours as far as I can tell, had raised the final price to $998!
Amazon Sony XBR55X850D $998.
Best Buy $999 and similarly others: Walmart, Beach Camera, etc.
Most of these shops did not change the List Price which they showed as $1,198.00. They all changed the Savings shown: it was $300 before, and it is only $200 today. Strange that all shops decided to change the amount of the Savings they offered.

Similar Samsung 4K TV examples showed an increase of $200.

Very eerie that all these different shops all increased their prices at the same time.