Sure thing it was manipulation. Crypto isn't regulated, therefore the whales can cause a splash and a wave.

The crash (speculating) had to do with 1) whales in elite circles planning buys and sells. 2) the printing of tether out of thin air (this is going to cause many more huge disruptions) 3) fake sell walls (sorta ties in with my first point) 4) the BS with Bitfinex (tied in with my second point) 5) some BS with coinbase and GDAX. 6) Tons of ICOs springing forth right around that time.

All of this happened at the same time so it's easy to see why (in hindsight) there was a 75% drop in basically all coins.