Segwit means Segregated Witness, a means to increase the block size of Bitcoin from 1 MB to 2 MB. In simple words, it will increase the transaction speed of Bitcoin which is a concern for past few weeks.
Now the crux of the matter is that Segwit is about to be installed in Bitcoin Protocols till the end of July and there are mixed response by miners for it's acceptance in Bitcoin platform. If Segwit gets approval then It will increase Bitcoin pricing very much in coming months but if not, the price of Bitcoin may fall down severely.
So, that's they hype. People are selling hugely in fear of losing more on later date. That's why market is crashing for a few days.
I hope you did understand this whole concept .
RE: When I look at the Cryptomarket...