coinbase has a habit of going offline when prices spike or fall this is the 3rd time this has happened within 2 months something seems suspicious.
Some would argue that the price goes down because of coinbase going down. creating a paradox where it seem like coinbase is trying to crash the market. for now coinbase is back up but still unable to accept buy or sell orders on ethereum.
whatever the excuse is I'm sure there are a lot of pissed off crypto buyers right now me being one of them!
for more detail click the link
https://www.cryptocoinsnews.com/bitcoin-ethereum-fall-coinbase-goes-offline-gdax-halts-trading/