What you are looking at has been called a Bart formation.

Basically if you ever watched the Simpsons and you notice how the son, Bart looks its similiar to this pattern.

The reason why this is happening more and more lately is due to poor liquidity and low volumes. Basically anyone with around 1000 BTC can easily make the market move up and down like that.

There are rumors that some whales do this on markets like Bitfinex so they can make large amounts of leveraged bets on the futures like OkEX and Bitmex.