BTC market is still so small and thinly traded that the biggest players can easily manipulate it. Especially, now when we have this shock "event" (halving). Of course, after the first difficulty after the halving is calculated, the situation will normalize (some thing like one week after the halving).

Also, now the ASIC technology has reached its local max (12-14 nm chips). So, it makes more sense for manufacturers to sell the miners than keep them. That should lead to better decentralization.