From what I have been seeing Bitcoin has been jumping $100 or more up and down today is a good example from $26 plus to $24 plus  a good $200 in the last few hours.

I did buy some at $2498 today then it dropped a little more I also have some in at $2540 and plan to buy more Monday if my wire transfer is done and the price is in the 24 to 25 range still.

I am signed up with

Coinbase
gdax
gemini
kraken
and
poloniex

With the top 3 it looks like I can buy in and out with US money so i do not get a drop after a sell.
and will use poloniex when i want to trade other coins.

Seems like the drop today in Bitcoin would be a bad deal in poloniex if you sold other alt-coins today.